FAQ

The stainless steel spray tower is a vertical wet exhaust gas purification equipment that achieves washing through countercurrent contact between gas and liquid. The exhaust gas enters the tower from the tangential inlet at the bottom, rises through the packing layer, and comes into countercurrent contact with the liquid sprayed by nozzles. Gaseous acid and alkali pollutants are captured by the liquid phase and neutralized, while dust and soluble substances are simultaneously carried away by liquid droplets. After washing, the gas is dehydrated by a mesh demister and discharged through the top exhaust stack via a fan. The absorption liquid falls into the bottom water tank of the tower and is then transported to the top of the tower by a circulation pump for repeated spraying and closed-loop circulation. The entire process ensures thorough gas-liquid contact, enabling continuous treatment of acid and alkali exhaust gas and acid mist, with stable operation and low maintenance requirements.

V0 rating indicates that the enclosure material self-extinguishes quickly upon contact with a flame in standard combustion tests, demonstrating strong flame retardancy. This significantly reduces the risk of the enclosure being ignited by external heat sources and the spread of flames along the equipment. However, it does not guarantee that the equipment will never catch fire. Activated carbon adsorbs organic substances, releasing adsorption heat. When adsorbing high concentrations of VOCs or when the bed fails to dissipate heat properly, the carbon layer may heat up. Both activated carbon and organic substances are combustible. Therefore, even with V0-rated enclosures, it is still essential to control inlet concentration and temperature, implement temperature monitoring and alarms, and adopt fire protection and shutdown purging measures. Do not mistake material flame retardancy for process safety. The fire protection design of the entire adsorption system must comply with regulations.

Both are acid and alkali resistant, differing in flammability rating. Standard PPs sheets have limited flammability with a low rating, while V0 PPs sheets self-extinguish quickly upon fire exposure and do not produce flaming drips in standard combustion tests, offering stronger flammability resistance. They are suitable for high fire protection requirements in indoor spaces, equipment layers, basements, etc. Standard PPs sheets can be used for outdoor or low fire protection requirement applications to control costs. When selecting, ensure the entire indoor system (ducts, fittings, dampers, flexible connectors) is made of V0 material and provides flammability test reports. V0 should not be used only locally, otherwise the system's flammability continuity will be compromised.

In scenarios with moderate acid gas concentration, low gas volume, water scarcity, or where cold conditions make water washing inconvenient, SDG dry adsorption can be used alone and achieves excellent results without wastewater or anti-freeze issues. However, for high concentration, high-temperature, high-humidity, or exhaust gases containing heavy mist droplets and dust, spray washing offers greater advantages in processing capacity, cooling, and adaptability. In such cases, it is recommended to first treat most of the acid gas with a spray tower, then use an SDG dry adsorption unit for final deep filtration. These two methods are not simple substitutes; they should be selected based on acid gas concentration, gas volume, temperature and humidity, on-site water supply and drainage conditions, and economic factors, and can also be used in series for complementary effects.

When the fan is operating, the motor and impeller generate vibration. If the fan is directly connected to a rigid duct, the vibration will be transmitted along the duct, causing duct resonance, bracket loosening, flange leakage, and noise amplification. In the long term, it may lead to fatigue cracking of welds and joints. A flexible vibration isolation break is formed between the fan and the duct by the soft joint, absorbing vibration displacement and compensating for thermal expansion and contraction of the duct and installation deviations. This is a common practice to reduce noise and protect the pipeline network. One soft joint is installed at both the fan inlet and outlet for more reliable vibration isolation. The soft joint should be installed as close to the fan body as possible, with independent brackets for both ends of the duct and equipment, keeping the soft joint in a free, non-load-bearing state. In addition to vibration isolation, the soft joint also facilitates fan disassembly and reassembly and correction of minor misalignments. If soft joints are not installed at the fan inlet and outlet, vibration and noise issues will significantly increase, and later modifications will also be more troublesome.

For ambient temperature, moderate corrosivity, budget-sensitive applications, and PVC duct systems, choose PVC dampers. They are economical, lightweight, have good rigidity, and feature easy splicing adhesive installation, suitable for general corrosion-resistant exhaust and building ventilation. For strong acids/alkalis, flammability requirements, higher gas temperatures, or PP welded duct systems, select PP or PPs dampers. They offer better temperature and corrosion resistance, and can be thermally welded and paired with flame-retardant materials. Both share the same structural principle, with the main differences being material temperature resistance, flame-retardant performance, and connection methods. Selection should be based on exhaust composition, temperature, fire safety requirements, and pipeline material. It's recommended to standardize valve material and connection methods within the same system for easier construction and spare parts management. When unsure about medium composition, choose materials for stronger corrosivity and higher temperatures to prevent premature aging and deformation of valves in critical areas.

Primarily determined by installation space and connection conditions. The equipment can only be placed indoors, in basements, or mezzanines when the ceiling height is insufficient for installing vertical towers, or when overhead craning is not feasible on-site. In such cases, a horizontal tower is selected, trading height for planar length. When the main exhaust duct is horizontally laid, it is desirable for the equipment's inlet and outlet to connect directly with the ductwork, reducing the need for vertical pipes and elbows, making horizontal tower connections more convenient. If outdoor space and height are not restricted, vertical towers offer higher counter-current mass transfer efficiency and occupy less area, typically being more economical. Both types operate on the same purification principle, with the choice primarily based on on-site layout conditions.

Both materials are made of polypropylene as the base material. The difference lies in that the PP sheet is added with flame retardant components during the production process, enabling the material to self-extinguish when exposed to fire. Ordinary PP sheet will continue to burn and produce dripping when it comes into contact with an open flame, whereas the PP sheet can prevent the spread of fire when exposed to flames and will extinguish itself once the heat source is removed. In applications requiring fire resistance, such as exhaust gas treatment and indoor ventilation, PP flame-retardant sheet should be selected. The acid and alkali resistance of both materials is essentially the same, and the welding processing methods are also identical.

Two-color PP flame-retardant sheet materials share the same basic raw materials and production processes. Prices primarily fluctuate with thickness, purchase volume, and market raw material conditions, with color itself typically not constituting a significant price difference. Beige is the industry's traditional color, with substantial market inventory, resulting in shorter delivery cycles for standard thicknesses. Porcelain white sheets are mostly produced based on orders, and small-batch purchases may involve slight variations in price and lead time. When inquiring, provide thickness, dimensions, and quantity to receive corresponding quotes. For large-volume purchases, custom-cutting can be negotiated to reduce edge waste and improve material utilization. If both colors meet the appearance requirements, prioritize the readily available beige for more reliable supply and replenishment.

Switch-type only has two positions, full open and full close, receives switch signal for air duct on/off and interlock; analog-type can receive continuous signal and stop at any position, and feedback continuous valve position signal for automatic air volume regulation. Variable air volume ventilators, negative pressure control, and frequency conversion linkage must use analog valves; simple equipment follow-up on/off can use switch valves. Analog valves are more expensive and have more complex control, choose based on whether continuous regulation is needed, do not use switch valves for frequent point-to-point simulation regulation.

Check valves installed on the outlet of indoor anti-corrosion fans, long-mounted in ceilings, pipe shafts, or workshops and connected to PPs flame-retardant ducts, become fire weak points in the entire flame-retardant pipeline system if made of ordinary combustible PP, potentially igniting first and spreading along the pipes during a fire. By adopting PPs flame-retardant check valves, the valve matches the flame-retardant grade of the duct and damper materials, self-extinguishing away from the fire, while retaining automatic anti-backflow functionality, meeting both fire protection and anti-corrosion requirements for indoor anti-corrosion exhaust engineering.

Capacity is determined based on daily chemical consumption, replenishment cycle, and preparation batches. Generally, the effective capacity is designed according to the chemical usage for several consecutive days of system operation, considering additional space for mixing and liquid level protection to avoid frequent daily preparation and prevent excessive chemical sedimentation or degradation due to large capacity. Complete dosing systems are often configured with one in use and one on standby or alternating double drums. Provide the treatment air volume, pollutant concentration, type of absorption chemical, and desired replenishment cycle, and the manufacturer or designer can calculate the capacity and number of drums accordingly.

The straight tee connects the branch pipe and the main pipe at a right angle, featuring simple processing and minimal space occupation. However, the direct intersection of airflow at right angles results in significant local resistance, making it suitable for areas with low branch pipe airflow, low wind speed, or limited space. The inclined tee joins the branch pipe to the main pipe at an acute angle along the airflow direction, ensuring smooth airflow convergence, low resistance, and low noise. It is preferred for high-flow branch pipes and systems with strict energy-saving and noise reduction requirements. When conditions permit, the branching and merging of exhaust main pipes should ideally use inclined tees to allow airflow to merge smoothly along the main pipe direction. In cases of budget constraints or limited space, small-flow branch pipes can use straight tees, but airflow dampers should be installed to balance resistance. Selection should consider the airflow ratio between the branch pipe and the main pipe, the included angle, and installation space, with particular attention to the impact of tee type on total resistance in high-flow, long-distance transportation systems.

Formed ducts are extruded or injection-molded with standard diameters and uniform wall thickness, offering low cost and fast delivery, suitable for branch ducts and conventional sections within the standard series; fabricated ducts are roll-welded from sheet metal with flexible diameters and wall thickness, capable of large diameters, thick walls, and special lengths, suitable for high-airflow main ducts, non-standard equipment interfaces, and specifications not covered by formed ducts; in projects, formed ducts are typically used for branch ducts and conventional sections, while fabricated ducts are used for main ducts and non-standard sections to balance cost and adaptability.

No. The function of PPs fire-rated dampers is to regulate airflow and isolate ventilation pipes, while fire self-extinguishing only indicates that the material itself is not easily combustible. It does not have fire protection functions such as temperature-sensitive melting, automatic closing, and fire integrity. According to fire protection codes, fire-certified fire dampers or smoke exhaust dampers must be installed where ducts penetrate fire compartments, machine rooms, and floor slabs. Fire-rated dampers only address the fire resistance of plastic pipes themselves and cannot be mutually replaced. Fire dampers must be installed at penetration points in accordance with building fire protection codes, and must pass construction drawing review and fire inspection.

When airflow changes direction at a bend, the velocity distribution is uneven between the outer and inner sides. The inner side is prone to forming eddies and flow separation, resulting in significant local resistance and noise, which is more pronounced at high airflow and high velocity. Flow guide vanes divide the air duct into several smoothly curved branch ducts, guiding the airflow to turn uniformly, which can significantly reduce the bend resistance coefficient. They also reduce wear and vibration on the outer side of the bend, showing notable effectiveness in large-section, high-velocity rectangular ducts. For small-section, low-velocity bends, the inherent resistance is limited, and flow guide vanes can be omitted to reduce costs and machining difficulty. Whether to install flow guide vanes and the number of vanes should be determined through resistance calculations based on velocity, cross-sectional dimensions, and deflection angle. For bends with flow guide vanes, the airflow direction must be noted—the flow curve should align with the direction of turn; installation in the opposite direction will be counterproductive. The ends of the flow guide vanes must be securely welded to the wall panels to prevent loosening during operation, which could generate noise.

The main advantages of square tubes are space-saving and flexible layout. When the workshop ceiling height is limited, pipes need to be attached to beams or ceilings, laid within suspended ceilings or equipment mezzanines, or need to connect with square air dampers or rectangular outlets of ventilation cabinets, choosing square tubes is more suitable, effectively utilizing flat and wide spaces and reducing bending. Round pipes have uniform stress distribution, low air resistance, less material consumption, and strong pressure-bearing capacity. They are preferred for outdoor main pipes and high-negative-pressure pipe sections. In practical projects, square tubes are often used in indoor compact sections, round pipes in outdoor main sections, and square-to-round transition fittings are used for smooth transitions at roof outlets or fan connections. Selection should be determined comprehensively based on building space, cross-sectional stress, and equipment interfaces. Rectangular tubes are commonly used in suspended ceilings, while circular tubes are preferred for long-distance transportation and high-negative-pressure sections. The combination of both maximizes space utilization and operational energy efficiency.

The exhaust from fume hoods contains acidic and alkaline gases generated during experiments, as well as potential volatile organic compounds (VOCs), which are corrosive. Plastic corrosion-resistant dampers are required. Additionally, fume hood exhaust ducts are often routed within ceilings and pipe shafts, spanning across rooms, floors, and fire compartments. Fire safety regulations mandate that duct materials be flame-retardant to prevent the spread of fire along concealed ducts and shafts. PPs flame-retardant square dampers meet both corrosion-resistant and flame-retardant requirements. Their rectangular cross-section matches the fume hood outlet and the flat-wide ducts within the ceiling, making them a common choice for laboratory exhaust systems. The damper should be paired with flame-retardant rectangular ducts and fire dampers to form a complete corrosion and fire protection system. When selecting, verify the flame-retardant grade of the material and the dimensions of the rectangular interface. Fire dampers must be installed at fire compartment boundaries, and plastic dampers cannot be used as substitutes.

Switched electric dampers are suitable for simple on/off control, remote actuation, interlocking, and maintenance isolation with low cost, while analog Adjustment electric dampers are ideal for continuous valve position adjustment based on sensor signals to precisely control airflow or maintain constant face velocity/negative pressure, with actuators receiving standard analog signals to stop at any angle; switched types are used for multiple branch circuits requiring only on/off control, while analog types are used for VAV fume hoods and VFD linkage systems.

Okay. The base material of the flame-retardant welding rod remains polypropylene, which is the same material as standard PP sheets. Upon hot melt, it can fuse reliably, and there are no issues with weld strength or seal integrity. When flame-retardant welding rods are used to weld standard PP sheets, the weld area will retain certain flame-retardant properties, but the other parts of the base material remain non-flame-retardant. Therefore, the overall flame-retardant rating of the component is still determined by the base material and cannot be altered by the welding rod. Conversely, standard welding rods are not recommended for welding flame-retardant PP sheets, as the non-flame-retardant weld joints would become the weakest points in the entire pipeline, burning first in the event of a fire. When welding flame-retardant sheets, flame-retardant welding rods should be used consistently to ensure the flame-retardant performance of the weld matches that of the base material. In engineering applications, welding rods should be procured in sets according to the base material type and color to avoid mixing.

For electric valves installed on standard indoor branch pipes and equipment interfaces within the PPs formed duct standard series, choose formed electric valves. They feature standard dimensions, fast delivery, low cost, and good interchangeability. For valves with sizes outside the standard series, used on large-diameter main pipes, or requiring special lengths, special flanges, or non-standard cross-sections, select plate-welded processed electric valves. The vane can be reinforced, the valve shaft thickened, and the actuator torque selection range is wider, allowing them to withstand higher air pressure. Both types operate on the same control principle, where the actuator drives the vane movement. The main differences lie in the size coverage range, structural strength, and delivery cycle. Selection should be based on duct size, air pressure, and installation location, with priority given to processed valves for large sizes, high air pressure, and non-standard applications. It is recommended to standardize connection standards and actuator models within the same system for easier spare parts replacement, wiring, and future maintenance.

The sleeve connection has low cost, a simple design, and excellent weld seam sealing, but it is non-detachable after welding, making it suitable for fixed, non-maintenance required straight pipe sections and long-distance dry pipe transportation. The flange connection has a slightly higher cost and larger dimensions, but it can be disassembled at any time, making it suitable for equipment inlets/outlets, valve and muffler ends, and areas requiring regular cleaning and maintenance. In engineering, sleeve connections are typically used for fixed transportation sections to control costs, while flanges are used for equipment and valve connections for maintenance. The two methods are used in combination based on the location. Detachable sections near vibrating equipment such as fans should be equipped with flexible connections and should not be welded shut with sleeves. When selecting, the connection type is determined based on whether the section requires disassembly, whether it is near equipment, while considering sealing performance, cost-effectiveness, and future maintenance.

Principles are similar, but direct interchangeability is not recommended. Plastic welding guns are designed for plastic hot melt welding, featuring stable temperature control, concentrated airflow, and a dedicated welding rod guide nozzle that heats both the welding rod and the joint simultaneously. Standard hot air guns are primarily used for film application, baking, and heat shrinking, with significant temperature fluctuations, dispersed airflow, and no specialized nozzles. This makes them prone to overheating, burning through, or uneven heating, resulting in unreliable weld strength. For load-bearing and sealing welds, specialized plastic welding guns with matching nozzles must be used to control penetration depth and shaping. Standard hot air guns can be used for auxiliary heating in non-load-bearing areas but cannot replace welding guns. With extensive experience in plastic equipment manufacturing and installation, equipping with a temperature-stable, specialized welding gun is more reliable.

For branches primarily focused on system commissioning and initial airflow balancing, where the opening does not need frequent adjustments, manual dampers are suitable. They offer low cost, simple structure, and do not rely on power or control signals, maintaining the set position long-term after initial adjustment. For dampers requiring automatic regulation based on pollutant concentration, ventilation cabinet door/window openings, or variable frequency system adjustments, or for those installed in hard-to-reach locations such as ceilings or shafts, electric or analog dampers should be selected. In the same system, manual dampers are often used for initial balancing in branch pipes, while electric dampers are installed at critical equipment and interlocking points for automatic control. The two are used in combination. For projects with limited budgets and simple control requirements, manual dampers are the primary choice. If conditions for future automation upgrades need to be reserved, an actuator installation position can be provided on the manual damper shaft.

The sight glass is made of acid-and-alkali-resistant transparent engineering plastic, which can be used for a long time in general acid-and-alkali mist environments. However, all transparent materials are subject to aging issues. Long-term exposure to certain strong oxidizing agents, organic solvents, or prolonged UV exposure may cause the sight glass to turn yellow, become brittle, reduce light transmittance, or even develop cracks, affecting visibility and strength. Therefore, the sight glass is designed as a replaceable structure with a bolt cover. When inspections reveal that the sight glass is cloudy, cracked, severely scratched, or the seal is compromised, simply replace the same specification sight glass and gasket without replacing the entire window. For daily cleaning, use a soft cloth and neutral detergent, avoiding abrasive scraping and strong solvent corrosion. For outdoor or high-light environments, choose weather-resistant, UV-resistant transparent materials to extend the service life of the sight glass.

Soft-sealed check valves exhibit minimal air leakage when the valve disc seats properly, the seal ring is intact, and there is reverse pressure; they can meet general anti-backflow and anti-cross-contamination requirements. However, as self-actuated ventilation valves, their sealing force derives from the valve disc's weight and reverse pressure differential, with limited sealing force when the reverse differential is small, making them not equivalent to actively tightened closed valves or industrial pipeline check valves. In scenarios involving strict isolation of hazardous gases, explosion-proofing, and personnel safety, electric or manual closed valves should be installed in series, not relying solely on check valves.

The price difference mainly comes from the sealing structure and the clamping mechanism. In conventional air dampers, the vane and body have hard contact, with a gap when fully closed, featuring a simple structure. For hermetic dampers, the vane requires machining for sealing grooves and embedding corrosion-resistant soft sealing rings, while the body must be equipped with flat valve seats. The handle must incorporate eccentric or four-bar clamping locking mechanisms, demanding higher machining precision and sealing material requirements. If only airflow balancing is needed, conventional regulating valves are sufficient; however, if post-closure isolation of harmful gases is required, hermetic valves must be used. Replacing them with conventional valves poses safety risks due to air leakage during maintenance.

Packing specifications should be selected based on tower diameter, gas flow rate, and purification requirements. As a general rule, packing diameter should not exceed a certain proportion of the tower diameter; using large packing in small towers can lead to severe wall flow and uneven distribution. For clean gas with high purification requirements, smaller specifications can be selected, offering larger specific surface area and sufficient mass transfer. For dusty or adhesive-containing gas, or when low pressure drop and high flow rate are required, larger specifications should be chosen for their strong anti-clogging capability. Common engineering practice involves calculating packing specifications and bed height based on empty tower gas velocity and liquid-to-gas ratio.

The foot pedal is designed based on personnel walking and conventional operational loads. The reinforced ribs on the back ensure that it does not deflect or crack under normal stepping by one or multiple people, meeting the needs for side-channel inspection and upper/lower hanging operations. Whether it allows for forklift passage depends on the pedal thickness, rib structure, perforation rate, and support spacing. The forklift load is significantly greater than pedestrian loads, requiring denser supports and the selection of heavy-duty, thickened foot pedals. When selecting, clearly provide load conditions such as forklift passage, wheel ground pressure, and frequency, configure the plate thickness and supports according to heavy-duty requirements, and avoid estimating based on standard pedestrian foot pedals. Standard pedestrian foot pedals should not directly bear concentrated loads from forklifts, material carts, etc. If unsure about the load, select based on the heaviest possible scenario and reinforce supports and beams separately in heavy-duty areas to ensure long-term use without deformation or damage.

When the duct diameter exceeds the standard series of injection molded dampers, or the vane strength and shaft seat load of the standard damper cannot meet the air pressure and diameter requirements, plate-welded processed dampers should be selected. Large-diameter valve vanes have a large wind area, and thin-walled formed vanes are prone to vibration and deformation. Processed dampers can thicken the vane, add reinforcement ribs, and thicken the valve shaft, equipped with bearings and worm gear mechanisms to improve rigidity and operational reliability. The specific dividing diameter varies among manufacturers and is related to air pressure, vane type, and installation method. After providing the diameter and air pressure parameters, the manufacturer determines whether to use formed or processed parts. Generally, the larger the diameter, the higher the air pressure, and the more special the requirements, the more likely plate-welded processed dampers are to be used. Non-standard dimensions and irregular interfaces are also typically achieved through processed dampers.

Rectangular duct sections are typically flat and wide. If a single large vane is used, the vane has a large span and thin plates, which are prone to vibration and distortion under wind pressure, while also exerting significant stress on the shaft, making operation difficult and sealing poor. Multi-leaf valves divide the large section into multiple narrow vanes, each with a small span, high rigidity, and low required torque. Synchronized drive via linkages ensures effortless operation and reduces vibration. Additionally, overlapping adjacent vanes during closure enhances airtightness. Therefore, single-leaf vanes are only used for smaller rectangular sections, while medium and large square sections predominantly employ multi-leaf linkage structures. Multi-leaf valves are also convenient for pairing with electric actuators, where a single active shaft drives all vanes. During selection, the number of vanes is determined based on the rectangular section dimensions and wind pressure. Larger sections and higher wind pressures require correspondingly more vanes and increased shaft rigidity.

This is a multi-leaf actuator linkage failure. First, check if the fixed screws of the valve shaft crank for the non-moving leaf are loose, if the connecting rod pins are dislodged or worn, or if the valve shaft is jammed by dust or foreign objects. Re-tighten the cranks and pins, align all valve leaves to the same reference angle before connecting the linkage rod, clean the jammed areas, and apply appropriate lubrication at the bushings. After treatment, power on or manually operate the entire set of valve leaves to observe if they move synchronously from fully closed to fully open and if the overlap is consistent. Do not assume the valve is functioning properly just by observing the actuator's movement. If individual leaves still fail to move synchronously, check if the valve shaft of that leaf is bent or if the shaft seat is deformed. Daily inspections should focus on the synchronicity and positioning of the valve leaves, addressing any issues promptly by shutting down the equipment to ensure accurate airflow regulation in each branch.

Both are essentially packed spray absorption towers, with the same working principle and structure. The main differences lie in their positioning and configuration focus: the acid mist purification tower is optimized for acid mist treatment, with the absorption liquid primarily being alkaline, emphasizing the treatment of acidic gases such as hydrochloric acid mist and sulfuric acid mist; the PP exhaust gas purification tower is a more general platform product, capable of treating acidic, alkaline, and other water-soluble exhaust gases by selecting different absorption liquids, with a broader scope of treatment targets. When selecting, there is no need to be overly concerned with the name; the key is to determine the absorption liquid, packing, and tower configuration based on the exhaust gas composition, concentration, and airflow, with the manufacturer completing the process design.

They serve different purposes. Reducers only change the cross-sectional size without altering the shape, with both ends being circular or both being rectangular, used for connecting pipes of the same shape but different diameters. Square-to-round transitions change the cross-sectional shape, one end rectangular and the other circular, used for converting between rectangular ducts, circular ducts, circular fans, or circular equipment; when the cross-sectional areas of the rectangular and circular ends are also different, square-to-round transitions also serve as diameter changers. Simple rule: for mixed square-round sections, choose square-to-round transitions; for same-shape diameter changes, choose reducers. In engineering, when connecting a rectangular horizontal pipe to a circular fan, square-to-round transitions, flexible connections, and reducers are often used in combination. When selecting, first draw the cross-sectional shapes and dimensions of both ends, then determine which one or ones of the fitting types to use in series.

Under similar specifications and loading conditions, multi-face hollow balls exhibit higher voidage, more unobstructed gas channels, typically lower bed resistance, and allow for greater processing air capacity with enhanced anti-blocking and anti-fouling capabilities. Raschig rings feature a simple structure and lower cost, but when randomly stacked, some internal channels within the rings may be obstructed, resulting in slightly higher resistance and relatively lower throughput. Multi-face balls offer greater advantages when Pursuit low pressure drop, high flow rate, or when the gas contains dust or viscous substances; Raschig rings are more practical when Pursuit mature reliability, cost-effectiveness, and when the gas is relatively dirty. The mass transfer efficiency of both materials is also influenced by spray density, liquid distribution, and bed height, and should not be evaluated solely based on the packing itself. Selection should consider tower diameter, free-tower gas velocity, liquid-to-gas ratio, and pollutant characteristics comprehensively. When necessary, allow the design to perform separate calculations for resistance and efficiency, or combine the two types of packing in layers within the same tower.

The hole size and open area ratio of the porous plate must be determined according to the application. For supporting purposes, the hole size must be smaller than the minimum external dimension of the supported filler or filter medium to prevent leakage, typically set as a fraction of the filler size with sufficient safety margin. For gas-liquid distribution purposes, the open area ratio should balance flow distribution effectiveness and resistance. An excessively small open area increases resistance and prone to blockage, while an excessively large open area reduces flow distribution effectiveness. A moderate open area ratio with uniform hole distribution is commonly used. For screening purposes, the hole size is determined based on the target particle separation size and screening efficiency, and may be designed with multiple hole sizes if necessary. During selection, provide the medium type, filler or particle size, treatment air or liquid flow rate, and installation space to match the hole size, hole pitch, hole pattern, and plate thickness. For applications requiring high flow distribution and screening accuracy, a small-scale or localized trial test can be conducted first to verify effectiveness before full-scale adoption.

Soft-sealed closed valves exhibit significantly lower air leakage compared to conventional dampers, achieving very low leakage levels under specified pressure differentials and with intact seals, but plastic ventilation dampers typically do not guarantee absolute zero leakage like industrial check valves. Selection should be based on allowable air leakage rates or leakage levels rather than a vague requirement for zero leakage. In scenarios involving highly toxic, flammable, or explosive gases or requiring strict isolation, additional measures such as blind flanges, double-valve series with venting should be employed, not relying solely on a single ventilation closed valve.

For vertical pipes and applications requiring high alignment accuracy, concentric reducers are recommended. They feature coaxial ends, symmetrical diameter changes, and uniform stress distribution, making them easy to support and arrange. In horizontal pipes, eccentric reducers are chosen if the top or bottom of the pipe needs to remain level after diameter reduction (facilitating venting and preventing air pockets at the top, or draining liquid and avoiding liquid accumulation pits at the bottom). The flat side of the reducer should face the side requiring level alignment. For horizontal exhaust pipes containing liquid or dust, eccentric reducers with level bottoms are commonly used to maintain a continuous slope at the bottom, preventing liquid or dust accumulation at the reduction point. Clean gas pipes without liquid can also be selected with level tops for easy installation along beam bottoms. The choice between concentric and eccentric reducers should be determined based on whether the medium contains liquid or dust, the pipe slope, and installation space. Before installation, verify the flow direction and the orientation of the flat side.

The upper part of the spray tower is usually equipped with an internal demisting baffle to meet general dehydration requirements. The independent PP demisting box is a separate gas-liquid separation device installed outside the tower, which can accommodate multiple stages of water collection plates or packing materials inside, offering higher demisting efficiency and facilitating maintenance and flushing. When the dehydration provided by the tower's built-in demisting baffle is insufficient, the exhaust stack carries excessive water, the downstream fan is prone to corrosion, or subsequent equipment like activated carbon is sensitive to water, an additional demisting box can be added outside the tower for secondary or fine demisting. Both devices operate on the same principle but differ in demisting level and installation location. The decision to add one should be based on the liquid load and subsequent process requirements.

Both types have their specific applications. Formed flanges are produced through injection molding, featuring standardized dimensions, flat faces, and Compliant sealing surfaces, with quick installation. They are ideal for bulk connections of standard-diameter ductwork and equipment, offering lower costs and are widely used in conventional engineering projects. Welded flanges are manufactured by turning sheet metal or splicing and welding, offering high flexibility and can be processed into non-standard dimensions, ultra-large diameters, and special-shaped flanges. However, their production cycle is longer and requires higher welding skills and machining precision. Standard specifications should prioritize formed flanges for stable quality and good interchangeability; welded flanges are used for non-standard, ultra-large diameters, or on-site irregular interfaces. When selecting, verify the diameter, pressure rating, and sealing surface type. It is recommended to standardize flange specifications within the same system to facilitate spare part interchangeability and future maintenance.

Energy savings come from three parts: improved motor efficiency, elimination of belt drive losses, and constant pressure variable frequency to avoid throttling. The comprehensive energy saving extent is related to the original fan efficiency, load rate, and operating time. Long-term continuous operation, large load fluctuations, and systems originally throttled by dampers have the greatest energy-saving potential. Specific values should be calculated based on the original fan nameplate parameters, actual operating current, and operating conditions, not just rely on promotional claims. For retrofit projects, energy consumption before and after Renovation can be compared under the same airflow and pressure, or the manufacturer can provide performance curves and energy efficiency data to calculate the payback period.

Torque must be matched with the damper. Calculate the required torque based on the damper vane area, differential pressure on both sides, shaft seat friction, and sealing clamping force, then multiply by a safety factor for selection. Insufficient torque will result in slow operation, incomplete movement, or even motor stalling and burning out; excessive torque is not economical and may damage the plastic valve shaft and body. For spring-return type dampers, excessive torque can also affect the reset fit. Generally, the damper manufacturer recommends actuator torque based on the valve type, size, and air pressure. Special calculations are required for large-diameter multi-leaf dampers and soft-seal enclosed dampers. When users configure actuators themselves, they should provide damper dimensions and operating conditions for the supplier to confirm.

Mainly selected according to pipe section and installation location. Round ducts, fan outlets, and exhaust stacks are matched with cylindrical mufflers, as round casings offer good pressure-bearing capacity and can directly interface with round flanges; rectangular ducts, ceiling installations, and indoor rectangular exhaust systems are matched with square plate mufflers. Both use the same noise reduction principle, with cylindrical mufflers typically employing annular acoustic layers or impedance composite structures, while square mufflers commonly use parallel acoustic panels. Do not rigidly connect a square muffler to a round system; when conversion is needed, add a square-to-round adapter and calculate the resistance.

The size of the grille openings is primarily determined by the filler dimensions. The principle is that the effective gap of the grille openings must be smaller than the minimum outer dimension of the filler to prevent the filler from leaking through the openings. At the same time, while ensuring no leakage, the open area should be maximized to reduce the resistance to gas-liquid passage. When loading small-diameter multi-faced balls or small specifications of Raschig rings, a dense grille with smaller openings should be selected. For larger specifications of fillers, a grille with larger openings and higher air permeability can be chosen. In addition to filler dimensions, the liquid holding capacity and air flow impact must be considered. For grilles with higher open area rates, the reinforcement spacing and support intervals should be checked. During selection, provide the filler specifications, loading height, tower diameter, and gas processing capacity to the manufacturer to match the corresponding grille opening type, plate thickness, and segment combination. For edge irregular areas, curved edge plates should be used to ensure that all gaps in the entire layer are smaller than the filler dimensions.

It relies on mechanical force balance for automatic adjustment. The conical valve core inside the valve is simultaneously subjected to spring force and aerodynamic force generated by the pressure differential between the valve front and rear, where the aerodynamic force pushes the valve core to close the passage and increase resistance when the pressure differential rises, and the spring opens the valve core when the pressure differential falls; the valve core moves to a force-balanced position, maintaining airflow constant within the design pressure differential range. The entire process does not require power supply, sensors, or control algorithms, hence it is called a self-powered constant airflow valve, with high reliability, making it particularly suitable for laboratory exhaust systems where electrical control complexity is to be avoided.

Face velocity should be determined based on the type of pollutants generated during experiments and relevant standards. Common chemical operations are typically controlled within the recommended face velocity range by standards, with specific values defined by laboratory ventilation design specifications and product requirements. Insufficient face velocity may allow harmful substances to escape, while excessive face velocity wastes air conditioning fresh air energy consumption and causes turbulence within the cabinet. Variable air volume (VAV) fume hoods maintain the set face velocity at any sash opening through sensors and regulating valves. Constant air volume (CAV) fume hoods only require face velocity compliance at the designed sash opening, and the face velocity changes with sash opening variations. This is the fundamental difference between the two systems.

Mainly treats acid mists and water-soluble gases that can be absorbed by water or alkaline solutions, such as hydrogen chloride, sulfuric acid mist, nitric acid mist, hydrogen fluoride, chromic acid mist, hydrogen cyanide, hydrogen sulfide, and other acidic gases, using alkaline solutions like sodium hydroxide for absorption; alkaline gases such as ammonia are treated with acidic absorbing solutions. It is not suitable for treating water-insoluble organic exhaust gases (e.g., benzene derivatives, esters, VOCs), which require processes such as activated carbon adsorption and catalytic combustion. When multiple pollutants are present, their solubility and reaction characteristics must be analyzed separately. Multi-stage, multi-process combinations may be necessary if required, with specific configurations determined by exhaust gas composition testing and process design.

The switch actuator is designed for two-position operation (fully open and fully closed) with only end stops inside, no intermediate position detection or servo control. Although theoretically, intermittent energization can temporarily stop the valve disc in the middle, it cannot achieve precise positioning and holding, frequent intermittent operation will cause motor overheating, accelerated wear of limits and gears, and cannot stably control airflow. For applications requiring intermediate position adjustment to control airflow, select corrosion-resistant actuators with analog control; for on/off applications, the switch type is the most economical and reliable, and the two should not be mixed.

The main difference lies in corrosion protection. Standard actuator housings are typically made of common metal or plastic, with lower sealing levels for junction boxes and fasteners made of ordinary steel. They are prone to terminal corrosion, shaft rust and seizing, and motor dampness failure when used in acidic or alkaline ventilation environments. Corrosion-resistant actuators feature corrosion-resistant housings or coatings, sealed junction boxes, stainless steel shafts and fasteners, and output shaft seals, specifically designed to withstand corrosive gases and salt spray. Corrosion-resistant actuators should be selected whenever the damper transports acidic or alkaline corrosive gases or is installed in a corrosive workshop. Ordinary models cannot be used as substitutes, otherwise, the failure rate and replacement frequency will be very high.

Depends on the primary noise reduction target. Fan noise propagates simultaneously to the inlet and outlet ducts; install the muffler on the fan inlet duct section to reduce noise at the workshop and collection points; install it near the exhaust stack at the fan outlet to reduce exhaust stack outlet and factory boundary noise; install at both inlet and outlet for high requirements. In corrosion-resistant exhaust systems, the fan outlet is often connected to an exhaust stack, making the outlet muffler most common. Installation position should be as close to the fan as possible to minimize sound transmission through unsuppressed pipe sections and pipeline Recycled noise.

First, check if the water tank liquid level is too low, or if the suction filter or suction pipe is blocked by filler fragments and sludge, causing insufficient suction. Then, inspect if the pump rotation direction is correct, if the impeller is worn or jammed by debris, if the outlet valve and nozzle are blocked, and if the pump's flow rate and head selection is too small. The handling sequence is to replenish the liquid level, clean the filter and nozzle, verify the rotation direction, and disassemble to inspect the impeller and flow channel. If the weakness occurs after the tower height is increased or the number of spraying layers is added, it is often due to insufficient pump head, requiring replacement with a pump of higher head. Spraying pressure and flow rate directly affect the purification effect. Abnormalities should be addressed promptly, and the filler should not be kept in a state of insufficient spraying for a long time.

No. Activated carbon exhibits good adsorption effects on most volatile organic compounds (VOCs) and odors such as benzene, toluene, xylene, esters, and ketones. However, it has weak adsorption capacity for low-molecular-weight, low-boiling-point substances (e.g., methane, ethylene). It tends to quickly saturate in high-concentration exhaust and may become ineffective due to pore blockage caused by dust, oil mist, or water mist. Strong acidic or alkaline gases may also corrode equipment. For water-soluble acidic or alkaline exhaust, a spray tower should be used first. High-concentration VOCs are best treated with catalytic combustion or regenerative thermal oxidation (RTO) processes. Activated carbon boxes are suitable for low-concentration, relatively uniform-composition organic exhaust and odor control with proper pretreatment. The gas composition must be clearly defined before selecting the appropriate type.

The exhaust airflow of a fume hood equals the face velocity multiplied by the sash opening area. The variable airflow damper acquires the sash opening degree and opening area in real time through the sash displacement sensor. The controller calculates the required exhaust airflow based on the set face velocity as the target value. Simultaneously, the actual exhaust airflow is measured in real time within the damper's measuring section. The actuator adjusts the vane opening based on the deviation between the two values, ensuring the actual airflow follows the target airflow. When the sash is opened wider or the opening area increases, the damper automatically increases airflow. When the sash is closed, airflow is automatically reduced. Therefore, regardless of the sash position, the face velocity remains within the set safe range.

The PP Activated Carbon Adsorption Tower is an equipment that utilizes the adsorption effect of porous solid adsorbent activated carbon to purify waste gas. Dust-containing gas is driven by a fan and enters the tower under positive or negative pressure. Due to the unbalanced and unsaturated molecular or chemical forces on the solid surface of activated carbon, when the solid surface contacts the gas, it can attract gas molecules, concentrating and retaining them on the solid surface, thereby adsorbing pollutants. After filtration, the purified gas enters the dust discharge system for high-altitude compliance emission. Activated carbon adsorption is a physical process, and the adsorbent needs to be replaced or regenerated after saturation.

The PP Cyclone Tower is a wet dedusting and purification equipment. The exhaust gas is introduced into the tower through ducts and, as it passes through multiple swirl blades, undergoes counter-rotating liquid spraying: clockwise blades in the first layer and counterclockwise blades in the second layer. The alternating collision of the gas phases enhances the separation of dust or paint mist residue through inertial collision, centrifugal separation, and liquid film adhesion, causing them to flow into the bottom of the tower. The swirl device utilizes the kinetic energy of the flue gas to generate aerodynamic swirl, enabling thorough contact between the gas and liquid phases for mass transfer reactions. The purified gas is then discharged by the fan after dehydration and mist removal in the third layer's mist separator. The absorption liquid falls to the bottom of the tower, where it is pressurized by a pump and recirculated for spraying.

The PP formed duct is made of PP polypropylene or PPs flame-retardant polypropylene material. The PP material features excellent chemical corrosion resistance, showing good corrosion resistance to inorganic acids, alkalis, and salts. It also has a low density, is easy to weld and process, exhibits good heat resistance and impact resistance, and is non-toxic and odorless, making it one of the engineering plastics that meet environmental protection requirements. The PPs flame-retardant material enhances the flame-retardant properties based on the PP base, making it suitable for applications with higher fire safety requirements. It can be selected according to the usage environment.

The PP formed elbows are primarily available in two standard angles: 90 degrees and 45 degrees. The 90-degree elbow is used for pipeline right-angle turns and is the most commonly used type, suitable for vertical and horizontal pipeline redirection. The 45-degree elbow is used for pipeline oblique turns, offering lower airflow resistance and is ideal for applications with higher requirements for wind pressure loss. In addition to these two standard angles, custom elbows with other angles such as 30 degrees and 60 degrees can be manufactured based on on-site pipeline layout needs, as well as special-shaped irregular elbows to meet complex pipeline routing requirements.

The PP processing duct is manufactured through processes such as cutting, coiling, welding, and flange reinforcement using PP flame-retardant sheet material. First, the sheet material is cut according to design dimensions, then coiled into circular or folded into square/rectangular tube bodies. The seams are securely connected using PP welding technology. Flange reinforcement rings are welded at both ends of the tube body for connection and strength enhancement. For large-diameter ducts, additional reinforcement ribs can be added to prevent deformation. The entire processing process can be customized to various dimensions and shapes based on customer requirements, offering high flexibility and suitability for non-standard ducts and large-diameter main pipelines.

The PP Flame Retardant Spray Tower is a wet-type exhaust gas purification equipment. Exhaust gas is introduced into the tower through ducts and comes into full contact with the absorbing liquid sprayed by the spray system as it passes through the packing layer. The acidic or alkaline pollutants in the exhaust gas are neutralized by the liquid phase. Subsequently, the gas is dehumidified and defogged by the demisting layer before being discharged into the atmosphere by the fan. The absorbing liquid falls to the bottom of the tower, where it is boosted by a pump and recirculated to the top for continuous spraying, thereby achieving the purpose of exhaust gas purification. The entire process ensures thorough gas-liquid contact, allows the absorbing liquid to be recycled, and has low operating costs. The equipment features a simple structure, stable operation, and convenient maintenance, making it a widely used purification device in industrial acid and alkaline exhaust gas treatment.

Huizhou Xicheng Environmental Protection Technology Co., Ltd.'s PP fire-retardant spray tower offers superior corrosion resistance and fire-retardant properties compared to fiberglass or carbon steel materials, making it particularly suitable for strong acid and alkali environments. Additionally, the PP material is lightweight, easy to install, and highly cost-competitive, featuring excellent comprehensive cost-effectiveness, making it an ideal choice for acid mist treatment. As a professional manufacturer of environmental protection equipment, Xicheng Environmental holds over 100 national patents and ISO9001 certification, and collaborates in industry-academia-research partnerships with universities such as Xi'an Jiaotong University and Tongji University. We provide end-to-end services, including solution design, equipment manufacturing, installation, and commissioning, to our clients. For technical consulting, please call 18038067815. Our professional team will offer customized solutions to meet your needs.

Huizhou Xicheng Environmental Protection Technology Co., Ltd.'s PP fire-resistant spray tower has low maintenance costs, primarily involving the regular replacement of nozzles, pumps, and filter materials. The equipment service life can reach 5-8 years, as the PP material has strong anti-aging properties, and the structural design is rational, reducing failure rates and helping customers lower long-term operating costs. As a professional environmental protection equipment manufacturer, Xicheng Environmental holds over 100 national patents and ISO9001 certification, and has industry-university-research cooperation with universities such as Xi'an Jiaotong University and Tongji University. We can provide customers with full-process services, including solution design, equipment manufacturing, installation, and commissioning. For technical consulting, please call 18038067815, and our professional team will provide customized solutions for you.

Huizhou Xicheng Environmental Protection Technology Co., Ltd. produces PP Flame-Retardant Spray Towers, which are suitable for treating industrial exhaust gases such as acidic, organic acid, and inorganic acid gases. They are particularly ideal for front-end exhaust gas treatment in industries such as chemical, electroplating, and painting. Made with flame-retardant PP material, the towers exhibit strong corrosion resistance and can effectively handle high-concentration, high-temperature exhaust gases, ensuring stable equipment operation. As a professional manufacturer of environmental protection equipment, Xicheng Environmental holds over 100 national patents and ISO9001 certification. Collaborating with universities like Xi'an Jiaotong University and Tongji University in industry-academia-research partnerships, we provide comprehensive services covering solution design, equipment manufacturing, installation, and commissioning. For technical consulting, please call 18038067815. Our professional team will offer customized solutions to meet your needs.

Xicheng Environmental Protection is a professional manufacturer of environmental protection equipment, mainly dealing in environmental products such as permanent magnet energy-saving fans, waste gas treatment equipment (PP spray towers, activated carbon adsorption towers, cyclone towers), and pipe fittings (PP/PVC pipes, elbows, tees, flanges).

它主要处理硫酸雾、盐酸雾、硝酸雾、碱雾、铬酸雾等酸碱废气和酸雾。也能洗涤部分可溶于吸收液的有机气体，以及含尘、含油雾的气体。与塑料塔相比，它更适合进气温度较高或带热量的腐蚀气体，常用于高温废气净化处理。含粉尘、油雾较多时，可增设旋流板或调整填料，强化除尘和防堵。吸收液按污染物成分配制，酸性气体用碱液、碱性气体用酸液。浓度和循环量按风量与浓度设计，高浓度工况可采用多级串联处理。

Equipment installed indoors, on equipment floors, in basements, or in areas with high fire protection requirements, and handling organic exhaust gas, should prioritize the selection of V0 PPs flame-retardant carbon boxes, paired with V0 flame-retardant ductwork and dampers to meet building fire protection and safety requirements. When equipment is independently installed outdoors, with sufficient fire separation distance from the factory, and in areas with lower fire protection requirements, standard PPs or other material carbon boxes can be selected to control costs. Regardless of the material, safety measures for activated carbon adsorption processes cannot be omitted. Specific configurations should be based on building fire protection design and local review requirements, with V0 configurations recommended for critical locations.

When standard specifications cannot meet on-site requirements, non-standard processing is required, such as: complex indoor pipeline routing, requiring a large number of custom-shaped elbows and tees; special equipment interface dimensions and orientations, needing transition pieces like round-to-square and square-to-round; custom rectangular sections constrained by ceiling height and structural limitations; matching with V0 flame-retardant equipment requiring unified material and flange specifications; retrofitting projects with limited space requiring on-site measurement and piping installation. Non-standard processing is manufactured section by section according to drawings, ensuring precise installation, but the processing cycle is longer than standard pipes. Drawings or on-site measurements should be provided in advance.

The replacement cycle depends on the type of acid gas, concentration, airflow, filter loading, and actual operating time. It can be theoretically estimated based on the adsorbent capacity and acid gas generation rate. During operation, the replacement point is determined by monitoring the outlet acid gas concentration. The filter media should be replaced when the outlet concentration approaches the emission limit (penetration point); it should also be replaced or treated if the pressure drop across the filter bed significantly increases, the filter media becomes clogged with dust, or it becomes hardened. In design, the filter media quantity is determined to ensure purification efficiency and a reasonable replacement cycle (typically lasting several months). During operation, establishing pressure drop and concentration records is more scientific than replacing based on fixed days, avoiding waste from premature replacement or exceeding limits due to delayed replacement.

Soft joints collapse under suction, typically due to insufficient stiffness in the corrugated section or excessively thin pipe walls, which cannot withstand the negative pressure at the fan inlet. During high airflow concentration, the pipe walls inwardly collapse, resulting in increased resistance and noise at a mild level, or blockage of the airflow path and insufficient airflow at a severe level. It is recommended to select soft joints with reinforced corrugations matched to the fan's negative pressure, avoiding excessively thin or long products. For large-diameter and high-negative-pressure fan inlets, it is particularly important to verify the pressure-bearing capacity of the soft joint. If necessary, support rings should be installed inside the soft joint or its length should be shortened. During installation, the soft joint should not be stretched to its limit, nor twisted or eccentric, maintaining a naturally slightly loose state. Collapse may also be caused by excessive airflow at the fan inlet, incorrect valve closure, or filter blockage leading to elevated negative pressure. The system conditions should be simultaneously checked. If collapse is detected, replace the soft joint with sufficient pressure-bearing capacity and eliminate abnormal negative pressure to prevent repeated damage.

Not suitable. PVC has a relatively low heat resistance temperature. Long-term passage of high-temperature gas will cause the valve body and valve disc to soften and deform, leading to valve disc jamming, poor closure, and even valve body damage, affecting system operation. High-temperature exhaust should use PP, fiberglass, or metal dampers. Pre-cooling sections such as spray cooling should be installed before the exhaust enters plastic equipment to reduce the temperature to within the material's allowable range. When selecting, both the normal continuous temperature of the exhaust and the potential peak temperature must be clearly provided, leaving a safety margin, and materials should not be selected solely based on normal temperature conditions. Even short-term high temperatures or frequent temperature fluctuations will accelerate the aging and deformation of PVC valves. For conditions with unclear temperature boundaries, it is advisable to directly select a material with higher temperature resistance to avoid the valve becoming the temperature weak link in the system. Replacing the valve after commissioning will affect production.

The horizontal tower primarily features cross-flow contact. Its single-stage mass transfer driving force is generally inferior to that of vertical counter-current towers, but through multiple-stage spraying, multi-section packing, lower internal tower velocity, and sufficient gas-liquid contact time, horizontal towers can still achieve the designed purification efficiency. Horizontally arranged washing equipment is well-established in engineering applications. Design considerations should determine the number of spraying stages, packing length, and liquid-to-gas ratio based on exhaust gas concentration and efficiency requirements, rather than simply scaling down from vertical towers. With proper design and maintenance, horizontal towers can reliably meet emission standards for low-concentration, high-volume acid and alkali exhaust gas treatment in indoor environments.

The PPs sheets are joined using hot melt welding, employing flame-retardant welding rods of the same material as the base material. The welding rod and the joint of the sheets are simultaneously heated to a molten state by a hot air gun and then pressed together to fuse. After cooling, a continuous and dense weld is formed. The welding quality depends on temperature control, welding rod selection, groove preparation, and welder proficiency. Properly executed welds can achieve strengths of over 80% of the base material. Thick plates and load-bearing welds should be grooved and welded in multiple passes. Visual and leakage inspections should be conducted after welding. After welding, the weld and the base material have the same material composition, retaining the same corrosion resistance and flame-retardant properties, without the rusting issues associated with metal welding. As long as the welding is performed according to the process and proper inspections are conducted, the sealing and service life of the weld area can match that of the base material.

From the perspective of welding strength and corrosion resistance, porcelain white welding electrodes of the same material can be used to weld beige panels. Both the electrode and the base material are polypropylene, and after hot melt fusion, the mechanical properties and corrosion resistance of the weld are unaffected. However, when porcelain white welding electrodes are applied to beige panels, they form distinct light-colored welds with a strong color contrast, affecting the overall consistency of the equipment's appearance. For equipment with high aesthetic requirements and exposed welds, it is recommended to use matching beige flame-retardant welding electrodes, as the weld color closely matches the base material, resulting in a harmonious and aesthetically pleasing finish. If welding is required in internal or concealed areas of the equipment, color difference is not an issue, and porcelain white electrodes can also be used. When purchasing, ensure to match the welding electrodes with the panel color and leave additional allowance for re-welding to avoid noticeable color differences later.

Both are standard analog signals. The 0-10V voltage signal features simple wiring and low cost, making it suitable for applications where the valve and controller are relatively close together and the electromagnetic environment is favorable. The 4-20mA current signal offers strong anti-interference capabilities, long transmission distance, and zero current during a break for easy fault detection, making it ideal for long-distance wiring and industrial environments with strong interference. When selecting, it must match the controller's output module. It is recommended to standardize the format in the same project. The signal type and valve position action direction (positive or negative action) can be set on the actuator.

No. The function of PPs fire-resistant check valves is self-extinguishing of materials upon separation from the fire source and automatic prevention of air flow reversal. They do not possess fire protection features such as temperature-induced melting, electric closure, or fire resistance integrity. When air ducts pass through fire-rated compartments, floors, or server rooms, they must be installed in accordance with fire protection codes using certified fire-rated dampers or smoke exhaust dampers. The fire-resistant check valves are installed in indoor pipe sections either before or after the fire dampers, each serving its specific purpose. Fire-rated dampers must be installed where air ducts penetrate fire-rated compartments or floors. No plastic valves can substitute for fire dampers. After installation, fire inspection and acceptance must be conducted in accordance with regulations.

PP exhibits excellent corrosion resistance to alkaline solutions such as sodium hydroxide and can be safely stored within ambient concentration ranges. Weld joints using the same material electrode will not be corroded by alkaline solutions. Attention should be paid to the exothermic effect of strong alkali dilution; when preparing, follow the operating procedures by adding water first, then slowly adding the chemical while stirring to avoid local overheating. The combination of concentrated alkali and high temperature will accelerate material aging, so design temperature should have a safety margin. For other chemicals such as strong acids, oxidizers, and organic solvents, verify the compatibility of PP separately – do not generalize that PP is resistant to all chemicals.

Three interfaces with the same size are equal-diameter tees, used for branching or merging of pipelines with the same diameter; when the main pipe diameter remains unchanged and the branch pipe diameter decreases, it is a reducing tee, used for diverting small branch pipes from a large main pipe. In ventilation systems, the airflow at each collection point is typically much smaller than the main pipe airflow, and the branch pipe diameter is also smaller, so the vast majority of branching uses reducing tees. Reducing tees maintain stable main pipe velocity while ensuring the branch pipe velocity meets gas transport requirements, making them a frequently used form in engineering. Equal-diameter tees are mostly used for splitting pipelines with the same diameter between main pipes, or for connecting equipment interfaces with the same diameter. When selecting, judge based on the actual diameters of the three interfaces. The reduction transition of the branch pipe should be smooth to avoid additional resistance caused by sudden reduction; if necessary, a reducing adapter should be installed separately after the tee.

The longitudinal seams of PPs ducts and circumferential seams of fittings in standardized welding are continuous and full. The welding electrodes melt seamlessly with the base material, ensuring no air leakage under normal use. Air leakage primarily occurs at weld defects such as incomplete fusion, porosity, or lack of penetration, or at worn-out or failed flange gaskets. During machining, bevels should be opened according to plate thickness and pressure, welding temperature and gun travel speed should be controlled, and thick plates should be welded in multiple passes. After welding, visual inspections of the ducts are required, and for high-purity systems, section-wise air leakage tests can be conducted. During installation, flange bolts should be tightened diagonally and evenly, with gaskets centered and intact. Butt welds should be fully welded along the circumference to keep the system's air leakage rate within the design range. If leaks are detected, mark their locations, perform patch welding or replace gaskets after pressure relief. Negative pressure duct sections, in particular, must ensure longitudinal seam and flange sealing.

When ordering, clearly specify the requirement for flame-retardant PPs material and agree on the flame-retardant grade. Request the manufacturer to provide the flammability test report for the corresponding batch of sheets. If necessary, conduct oxygen index or vertical burning tests according to standards. On-site verification can be performed through sheet markings and quality certificates. Flame-retardant PPs sheets and ordinary PP sheets have similar appearances, making them difficult to distinguish by the naked eye. Relying on methods like burning smell for identification is unreliable. For critical projects, clearly state material standards and acceptance criteria in the contract to prevent the substitution of ordinary PP for flame-retardant sheets.

The distinguishing basis is the plane where the airflow changes direction after installation. Horizontal elbows cause the duct to turn left or right within a horizontal plane, with the side plates of the elbows placed horizontally; vertical elbows cause the duct to bend up or down, with the duct turning within a vertical plane. Although their processing structures are similar, their installation directions and side plate stress differ, making them not easily interchangeable. When ordering, it is essential to specify on the drawing whether it is a horizontal or vertical elbow, left or right turn, upward or downward bend, as well as the elbow angle to avoid directional errors that could lead to on-site installation issues. For ducts installed against walls or beams, the relationship between the elbows and the wall or beam bottom must also be noted. Elbows with flow guides also require the indication of the turning plane. Before installation, verify the elbow direction against the drawing and on-site layout to ensure the curvature center and airflow direction align before positioning, which can prevent the need for a full rework.

Buckling or concaving of the panel surface indicates insufficient panel reinforcement. Rectangular large panels will warp under differential internal and external pressure. Reinforcing bars or frames must be installed based on the magnitude of negative pressure and the panel span to divide the large panels into multiple smaller cells, reducing unsupported spans. Square tubes showing obvious deformation should be taken out of service. Additional reinforcement and denser support brackets must be added externally, and thicker materials or smaller cross-sections may need to be replaced if necessary. During the design phase, panel thickness and reinforcing bar spacing must be verified against the full pressure of the fan. It is crucial to address buckling or suction collapse during installation rather than waiting for post-installation remediation, especially for high-negative-pressure systems. The specifications, spacing, and welding methods of reinforcing bars must match the panel thickness and cross-section. For pipe sections with high negative pressure, reinforcement should also be added near the flanges. After commissioning, focus on observing the panel for breathing fluctuations and abnormal noises. Stop the machine and address deformation promptly upon detection.

Variable Air Volume (VAV) fume hoods require the exhaust airflow to be automatically adjusted when the door opening varies, while maintaining a constant face velocity. This necessitates the use of analog electric regulating dampers. The actuator receives standard electrical signals from the controller, continuously adjusts the vane angle, and feeds back the actual vane position to the control system, forming a closed-loop control. Standard on/off electric valves can only be fully open or fully closed, and manual valves require manual adjustment, neither of which meets the requirements for real-time, continuous regulation. Constant Air Volume (CAV) fume hoods or conventional exhaust hoods can be balanced once using manual multi-leaf dampers. Whether to use automatic dampers depends on the control method of the ventilation system. When a laboratory has multiple VAV fume hoods, it is common to install one analog valve per hood outlet, with the building management system centrally managing the fan frequency conversion and airflow balancing.

For standard electric actuators, after power failure, the valve remains in the position at the moment of power interruption and will not automatically open or close. When power is restored, it continues to operate according to the control signal. If the process requires the valve to automatically open during power failure (e.g., emergency ventilation, ensuring air circulation) or automatically close (e.g., preventing gas backflow, isolating equipment), a spring-return actuator should be selected: when powered, the motor overcomes the spring force to maintain the working position, and after power failure, the spring pulls the valve disc to the preset safe position. When ordering, the requirements for the power-off safe position and the return direction must be clearly specified. Standard hold-type and spring-return-type structures and prices differ and cannot be mixed. For high-safety requirement environments, manual reset and position feedback can also be added. During design, the safety strategy after power failure should be considered for each unit to avoid the valve being stuck in the wrong position in case of an accident.

It is not advisable to make the transition section too short. The shorter the diameter change section, the larger the cone angle, especially during gradual expansion, where airflow is prone to detaching from the cone wall, forming a vortex zone, significantly increasing resistance and noise. An excessively short reducing adapter approaches a sudden expansion, losing the significance of smooth transition. The gradual expanding reducing adapter should control the expansion angle and ensure sufficient length to gradually decelerate the airflow along the cone wall. The cone angle of the gradual converging reducing adapter can be slightly larger, and the length can be appropriately shortened. The reasonable length balances material savings and resistance control. It can be calculated based on the diameter difference between the two ends and the recommended cone angle, rather than being arbitrarily determined based on installation clearance. When space is indeed limited, segmented diameter changes or flow-directing structures can be added at the transition points. Design priority should be given to ensuring the transition length at critical areas such as fan inlets and outlets, which significantly reduces fan energy consumption and vibration impact.

The selection criteria mainly include joint clearance, plate thickness, and bevel type. For thin plate ducts with small gaps, fine round welding electrodes are typically used for root welding, followed by slightly thicker round electrodes for cover welding, resulting in smooth welds and reduced material consumption. For thick plates, after V-shaped beveling, round electrodes are used for root welding to ensure full penetration. The fill and cover layers are more efficient with triangular electrodes, as their triangular cross-section provides a larger contact area with the bevel, fewer fill layers, and a fuller weld profile. Double-bead electrodes have high deposition rates, making them suitable for large-area thick plate seams and longitudinal joints of cylinders, but they require higher welding torch power and more skilled welder techniques. When purchasing, match fine round, thick round, and triangular electrodes according to common plate thicknesses, using round electrodes for corners and roots, and triangular electrodes for large bevels. Weld electrode specifications must correspond to the welding torch nozzle diameter; mismatched specifications will affect wire feeding and fusion.

Interlocks prevent fans from starting under closed duct conditions, which can cause pressure buildup, current overload, duct collapse, and equipment damage. They also automatically close valves after fan shutdown to prevent outdoor air from infiltrating, corrosive gases from spreading in the workshop, and cold air from entering pipelines and rooms during winter. The standard interlock sequence is to open valves first during startup, then start the fan upon receiving the "fully open" signal, and to stop the fan first during shutdown, followed by delayed valve closure. When multiple branches share a fan, the control system opens the corresponding branch valves based on the number of operating units and required airflow, and may adjust fan frequency control as needed. Interlock logic is implemented by relays or programmable controllers in the control cabinet, with valve position feedback and fault alarms configured. Valve-to-fan interlocking is a fundamental requirement for exhaust automation, and the commissioning process must verify the sequence of valve opening, fan startup, fan shutdown, and valve closure, as well as timeout protection for each step.

Properly installed ring flanges with spigot welding will not leak air. The key lies in ensuring the two ends of the ducts are inserted correctly and the axes are aligned. The annular gap of the socket should be continuously welded around using a weld wire of the same material, without any breaks, pores, or incomplete welds. Before welding, clean the oil and oxide layers from the socket. During welding, ensure the weld wire fully fuses with the base material, and no stress should be applied to the weld before it cools. For systems with high sealing requirements, air leakage tests or segmented pressure checks can be conducted after welding. Air leakage typically occurs when the weld is not closed, the weld wire does not fully fuse with the base material, or the socket is not inserted properly. These are all construction quality issues. As long as the connection is properly inserted according to the process, fully welded around the circumference, and post-weld checks are performed, the sealing performance of the ring flange joint can meet the requirements of corrosion-resistant ventilation systems.

Poor electrode adhesion is usually caused by cold soldering, common reasons include low temperature, gun movement too fast, seams not cleaned properly, or insufficient electrode pressure. First confirm the gun temperature reaches PP melting requirements, remove oxidation and contaminants from the seam surface with a scraper before welding, ensure the electrode and base material show a molten glow simultaneously during welding, keep the electrode perpendicular to the weld and apply stable pressure. Test weld with scrap material before actual welding, after cooling, forcefully peel the weld to check, a well-fused weld should not tear along the joint surface.

The standard manual air damper is primarily used for air volume regulation. There is a clearance between the damper blade and the body, resulting in a certain amount of air leakage even when fully closed, making it unsuitable for complete replacement of airtight dampers. In applications requiring high closing airtightness, for maintenance isolation, or to prevent gas backflow, it is recommended to select airtight dampers with soft sealing strips on the blade edge or specialized airtight dampers. While general air volume balancing allows for a small amount of air leakage, applications such as maintenance isolation, preventing gas backflow, and hazardous material ventilation demand higher closing tightness. When selecting, it is essential to distinguish between regulating dampers and airtight dampers, as standard regulating dampers should not be used for isolation tasks. When closed, airtight dampers compress the soft sealing strip against the seat, resulting in significantly less air leakage compared to standard dampers, with corresponding increases in price and operating torque.

Window air leakage is usually caused by aging of the sealing strip, loose fastening screws, or deformation of the viewing panel. First, re-tighten the screws in a diagonal order to ensure even pressure distribution on the cover, and observe if the air leakage is eliminated. If the leakage persists, shut down the machine and release pressure, then disassemble the window to check if the sealing strip has lost elasticity, been corroded, or has joint gaps. Clean the sealing surface, replace the new sealing strip, and reassemble it. Deformed, warped, or cracked viewing panels must be replaced in their entirety and cannot be used Struggle . During installation, the sealing strip must be continuous, smooth, and tightly sealed at joints. Ensure uniform screw torque to avoid uneven tightening or excessive force that could crack the panel. After assembly, perform an air leakage check, and conduct a follow-up inspection during operation. Regular inspections should focus on detecting crystallization, leakage, and loose screws around the window. Address any issues promptly to maintain long-term sealing performance.

The valve disc, in low airflow or fluctuating conditions, may remain partially open, repeatedly lifted and dropped by airflow striking the seat, generating noise and wear. Common in low-load fan operation, fluctuating multi-fan parallel conditions, or excessively light valve disc or improper positioning. It can be eliminated by adjusting fan operating conditions to maintain stable airflow, selecting check valves with damping buffers, or adjusting valve disc weight or positioning. Systems with variable frequency low-speed fan operation require particular attention to valve disc stability, and electric interlock valves may be used if necessary.

Manual hermetic valves require not only rotating the valve disc to the fully closed position but also continuing to operate the handle to complete the eccentric or four-bar pressing action and lock it, ensuring the seal ring is uniformly pressed against the valve seat in a circular pattern to achieve a reliable seal. If leakage persists after tightening, check whether the seal ring is aging or deforming, or if it is obstructed by foreign objects; whether the valve seat is deformed; whether the valve disc compression stroke is properly positioned; and whether the valve shaft is securely fastened. Before closing, clean the dust, crystals, and debris from the valve disc and valve seat. Fine particles trapped on the sealing surface can cause localized gaps and air leakage, which is a common issue on-site. After treatment, repeatedly open and close the valve a few times to verify the seal. Replace the seal ring promptly if it shows indentations, hardening, or cracks. During installation, ensure the valve body is coaxial with the pipeline and that the flanges are evenly loaded to prevent valve seat deformation, which could affect the seal.

Under the same specifications and loading conditions, the structured packing has a more complex configuration, typically featuring a higher specific surface area and voidage, leading to more thorough gas-liquid contact and higher efficiency, but at a slightly higher price. The Raschig ring, on the other hand, has a simpler structure, high throughput, strong anti-blocking and anti-fouling capabilities, is cost-effective, and has low replacement costs. When the gas is dirty, contains solid or viscous substances, or when economic reliability is prioritized, Raschig rings are often used with appropriately increased specifications. For cleaner gas requiring higher purification efficiency, structured packing can be employed to enhance mass transfer performance. The two types of packing can also be combined in layers within the same tower: the lower section near the inlet uses large-scale anti-blocking packing, while the upper section employs high-efficiency packing for fine treatment, balancing anti-blocking and efficiency. Actual performance also depends on spray distribution, packing height, and gas-liquid ratio. Selection should be based on pollutant concentration and compliance requirements, with reference to similar project packing configurations when necessary.

The footrest is an elevated working surface, with drain holes on the plate surface allowing spilled chemicals and rinse water to drain quickly below the plate. The ground should be equipped with anti-corrosion flooring and diversion channels to direct the liquid to collection tanks or wastewater treatment systems, achieving dry-wet separation and clean-pollution diversion. The footrest only addresses anti-slip, anti-corrosion, and leakage issues on the working surface and cannot replace ground corrosion protection and waste liquid collection facilities. During design, ensure smooth integration of plate perforations, ground slope, and diversion channels to prevent liquid accumulation on the plate or ground. Regularly clean the area below the plate, supports, and diversion channels to remove accumulated chemicals and sludge, preventing liquid buildup that could corrode supports and flooring. Promptly repair and clear any damaged flooring or blocked diversion channels to establish a complete path for plate leakage, ground collection, and centralized treatment, avoiding chemical overflow that causes corrosion and safety hazards.

The large valve disc has a wide wind-receiving area and significant aerodynamic torque, making manual operation with the handle very labor-intensive. It should be equipped with a worm gear reducer, allowing the valve disc to be rotated with minimal torque using the handwheel. The worm gear also features self-locking functionality to prevent the valve disc from being moved back by airflow. If the valve still sticks after installing the worm gear, check whether the valve shaft and shaft seat are concentric, whether the bearings are contaminated with dust or crystallized, and whether the valve disc is deformed by heat, causing wall friction. Clean the crystallization, correct the concentricity, and apply lubricant. Avoid using a force pipe to hard turn the handle, as this may break the valve shaft, damage the worm gear, or deform the valve disc. For large-diameter valves, inspect the welds of the valve disc reinforcement and shaft seat for cracks. After treatment, perform several full open/close cycles to ensure uniform torque. If necessary, the manufacturer should verify whether the actuator torque matches the requirements. Valves that have been stuck for a long time should have their bearings replaced or undergo overall maintenance.

Leaf valve leaf synchronization issues are typically caused by loose or Detachment of the coupling pin in the linkage rod, or loose of the crank fixing screw, resulting in some valve leaves not rotating with the main shaft. The machine should be shut down to inspect the linkage rod, crank, and pins. Worn pins should be tightened or replaced, and the fixing screws should be locked. All valve leaves should be manually adjusted to the same angle and the linkage rod repositioned. After the treatment, perform several full-cycle openings and closings to observe whether all leaves open and close consistently, without delay or jamming. During routine inspections, pay attention to the consistency of the opening, ensure the linkage mechanism is not jammed by debris or crystallization, and maintain cleanliness at the pin locations. In corrosive environments, promptly replace rusted metal linkage components or select cranks with corrosion-coated covers. After adjusting the synchronization mechanism, mark it for future reference to check for displacement.

Depends on the total torque of the vane assembly. The aerodynamic torque of each vane in the multi-vane valve is Summary ed to the active vane shaft via linkages; the larger the cross-section, the more vanes, and the higher the wind speed, the greater the total torque. If the total torque falls within the rated torque range of a single actuator with a margin, one actuator is sufficient; for excessive torque, a high-torque actuator can be selected, or the valve can be divided into two groups, each equipped with one actuator for synchronized control. When selecting, provide the cross-sectional dimensions and wind pressure; the manufacturer calculates the torque, and actuators should not be matched based solely on experience with small valves.

It is generally not recommended to mix acidic and alkaline exhaust gases in the same tower for simultaneous treatment, as the absorbent can only maintain one pH level, and certain gas mixtures pose safety risks. For example, mixing cyanide-containing exhaust with acidic gases may produce highly toxic hydrogen cyanide gas, while ammonia mixing with acid mist can form ammonium salt crystals that block the system. The correct approach is to separately collect, transport via dedicated pipelines, and treat acidic, alkaline, cyanide-containing, and organic exhaust gases in individual towers, each using the corresponding absorbent. Shared equipment can only be considered when the components are compatible and the process allows for alternating operation. Specific requirements must be determined by process design in accordance with safety regulations.

The transition section length must ensure a smooth conversion from square to circular twisted surface, while also meeting the requirements for gradual expansion and contraction angles to avoid flow separation at sharp turns. If the transition section is too short, the twisted surface becomes abrupt, leading to increased flow vortices and resistance, and may also cause vibration and noise in the flat section under negative pressure. If it's too long, it results in material waste and occupies more installation space. Generally, the appropriate length is determined based on the rectangle's longer side dimension, the circular end diameter, and the area difference between the two ends to ensure a smooth twisted and conical surface. The square-to-round transition at the fan inlet must particularly guarantee uniform airflow into the impeller. When necessary, refer to the fan manufacturer's connection requirements and recommended length for design. In space-constrained situations, it can be shortened appropriately, but the resistance should be checked and stiffeners added to the flat section to prevent resonance.

The multi-sphere balls are spherical and lightweight. Under high gas velocity, especially during fan startup, valve sudden opening, or load fluctuation, the upper spheres in the bed may be lifted, rolled, or fluidized by the airflow, leading to long-term wear and carryover. Therefore, the design requires controlling the empty tower gas velocity within the allowable range of the packing and not exceeding the fluidization point gas velocity of the packing. Pressure plates, pressure grids, or limiting gratings should be installed above the packing layer to confine the balls within the bed. During fan startup, the air damper should be closed slightly, and the air volume should be adjusted slowly to avoid instantaneous airflow impact on the bed. Avoid frequent and large load fluctuations during operation. A small clearance should be left between the pressure plate and the packing to limit the upward floating without crushing the balls. If balls are still carried into the demisting section, review whether the air volume exceeds the standard or the pressure plate gap is too large, and supplement a pressure grid above.

Both can support fillers, but their structures and applications differ. The integral grating plate is a standard injection molded part with high hole rate, light self-weight, quick assembly, and low cost, making it suitable for supporting large-particle bulk fillers under standard tower diameters, with easy batch supply and replacement. The porous plate is punched from a whole plate, allowing the hole size to be made very small, and the hole type and open area rate can be customized, making it suitable for supporting fine-particle filter media, activated carbon, as well as for airflow equalization plates, screening plates, or used in non-standard sizes and irregular spaces. For large-particle fillers and conventional towers, the grating plate is more economical; for fine-particle filter media, gas-liquid equal distribution, and solid-liquid screening, the porous plate is more appropriate. The two can also be used together, for example, the grating plate supporting the main filler with an additional porous equalization plate above. When uncertain, calculate separately based on the minimum filler size and tower diameter to quickly determine the solution.

The design objective of the closed valve is to achieve full open, full close, and airtight isolation. The soft seal ring is pressed against the seat when closed and detaches from the seat when open. If it is left in the intermediate position for long-term adjustment, the seal ring will be continuously eroded by high-speed airflow accompanied by vibration wear, and the valve disc's pulsation at small openings will also damage the sealing surface and clamping mechanism, leading to increased air leakage when fully closed and reduced seal life. For pipe sections requiring frequent air volume adjustment, analog control valves should be selected, and closed valves should be installed separately at isolation points to perform their respective functions. In practical engineering, regulating valves and closed valves are often arranged in series. The regulating valve is responsible for daily air volume balance, while the closed valve only operates during maintenance or shutdown. This approach ensures both adjustment accuracy and protects the closed valve's sealing components, avoiding premature failure of a single valve being used for two different operating conditions.

Miter joints are typically made with socket connections. After inserting the duct into the socket, use weld electrodes of the same material to perform circumferential sealing along the joint. Alternatively, add bolts at the socket and pair them with sealant for fastening. This method offers quick installation and excellent sealing, making it suitable for fixed pipe sections. For locations requiring frequent disassembly for maintenance or connections to equipment,Flange connection (flange connection) is recommended. Both ends of the miter joint are equipped with flange edges, which connect to the duct or equipment flanges using bolts and gaskets for easy assembly and disassembly. Socket welding is cost-effective and airtight, while Flange connection provides flexibility and facilitates replacement. Choose the appropriate method based on the specific application. Regardless of the connection method used, inspect the joint for tightness and proper alignment after installation to prevent corrosive gas leakage. Negative-pressure pipe sections, in particular, must ensure continuous welds and intact gaskets. Post-installation, integrate system air leakage testing to verify the integrity of the connections.

Tiered Troubleshooting: First, confirm whether the actual airflow exceeds the design value. Excessive gas velocity may cause liquid droplets to fail to separate or even lead to secondary entrainment. Reduce the airflow or increase the demisting section. Check if the baffle spacing is too large, the installation direction is incorrect, or the packing is improperly installed, causing short circuits. Verify if the liquid droplets are too fine and exceed the current internals' collection range, considering switching to packed or two-stage combined demisters. Inspect if the flushing water is excessive or if the liquid seal drain pipe is blocked, resulting in water accumulation inside the box. Adjust the airflow, reinstall the internals, increase the number of demisting stages, or switch to denser water collection plates to address the water carryover issue, which typically resolves the problem.

Flange leakage is typically caused by gasket aging, bolt loosening, flange face misalignment, or seal surface damage. First, check if the bolts are tightened evenly in a diagonal sequence. Bolts may loosen due to thermal expansion and contraction of pipelines and operational vibration. Re-tightening them according to specifications can eliminate most leaks. If leakage persists, shut down and relieve pressure, then disassemble the flange to inspect if the gasket is damaged, misaligned, or aged. Replace the new gasket and re-center the installation. For warped or deformed flange faces or scratched seal surfaces, the flange needs to be replaced or the seal surface machined. Do not excessively increase bolt torque to force a seal, as this may crack the plastic flange. Establishing records for bolt tightening and gasket replacement during routine maintenance can effectively reduce repetitive leaks.

A-Style Direct Connection: Compact structure, high transmission efficiency, no belt slip or replacement/maintenance required, and alignment guaranteed by the factory; disadvantages: impeller is directly mounted on the motor shaft, resulting in the same speed as the motor. Changing airflow primarily relies on VFDs, and impeller failure can affect the motor shaft.

C-Style Belt Drive: Allows flexible speed adjustment through pulley ratio, isolates some vibration, and the motor does not directly contact the overcurrent gas. However, it has transmission losses, requires regular belt tensioning and replacement, and involves extensive alignment maintenance.

With the maturation of permanent magnet VFD technology, the energy-saving and maintenance-free advantages of direct connection solutions are becoming increasingly prominent in corrosion-resistant fans.

Cannot be simply interchanged. Switching actuators do not have servo control circuits internally and can only be fully open or fully closed, unable to stably hold a mid-position; they will frequently operate and fail to position accurately in variable air volume control applications. Adjustment-type actuators can be used as switching actuators, but at a higher cost. Spring-return type and standard type actuators have different power-off behaviors and cannot be arbitrarily replaced. When replacing actuators, maintain consistency in control method, voltage, torque, travel time, signal format, and reset method, otherwise it may cause control failure or loss of safety functions.

When the fan noise is primarily in the medium-to-high frequency range, a conventional cylindrical reactive muffler can suffice; when the noise spectrum features prominent low-frequency components, noticeable fan pulsation noise, or when simply extending a reactive muffler does not meet low-frequency requirements, an impedance Composite (impedance Composite ) muffler should be selected, utilizing expansion chambers and resonance chambers to target low-to-medium frequency noise attenuation. Centrifugal fans, positive displacement fans, and high-pressure systems often exhibit significant low-frequency noise. The most prudent approach is to first measure the fan noise octave band spectrum and determine the reactive and resistive section configurations based on the required noise attenuation for each frequency band, avoiding Blindly extending (blindly extending) the reactive section.

The load-bearing capacity of grating plate is related to the plate thickness, the structure and orientation of the reinforcement bars, the support span, and the wet weight of the fill material. Injection molded grating plate can bear the weight of conventional bulk fill material and liquid weight within a reasonable spacing of support rings and beams. For large-diameter towers, the load-bearing capacity is ensured by densifying support beams, increasing segments, and reducing the span of individual plates. In design, the total load should be calculated based on the fill material's bulk density, loading height, liquid volume, and potential maintenance loads, and then the plate thickness, reinforcement bars, and support spacing should be determined accordingly. The span of grating plate should not be excessively large without intermediate support, otherwise, long-term loading may cause deflection, deformation, or even detachment. When selecting, prioritize plates with rationally arranged reinforcement bars and solid molding. For conditions with high liquid volume and loading height, the spacing of support beams should be appropriately densified.

It is not absolutely constant but maintains airflow within an allowable deviation range under specified working differential pressure. Venturi valves have applicable upper and lower limits of differential pressure: when the differential pressure is below the lower limit, the spring pushes the valve core to its maximum opening but still fails to maintain airflow; when the differential pressure exceeds the upper limit, the valve core closes to its minimum position but cannot fully compensate, and airflow will still vary outside the working range. When selecting, ensure that the differential pressure across the valve before and after normal system operation falls within the working range. Consider pressure changes caused by fan frequency variation and filter blockage, and have the design personnel verify if necessary.

The cabinet body and lining of the PP fume hood are made of polypropylene, which is resistant to acid, alkali, and salt corrosion, does not rust, and is suitable for laboratories that frequently use hydrochloric acid, nitric acid, sulfuric acid, alkaline solutions, and corrosive gases in chemical, electroplating, and semiconductor fields. The all-steel fume hood has high strength and good performance in high-temperature and organic solvent resistance, making it suitable for laboratories primarily using organic reagents and high-temperature heating. The surface is treated with anti-corrosion coating, but its resistance to strong corrosion is inferior to PP. For highly corrosive environments, choose PP; for organic solvents and open flames at high temperatures, select all-steel or stainless steel. When the medium is complex, specify the commonly used reagents to the manufacturer for material selection.

Common reasons include: insufficient circulating caustic soda concentration or long-term non-replacement, leading to saturated absorption capacity; insufficient spray volume, nozzle blockage, or uneven spraying, resulting in dry zones in the packing layer; packing blockage, crystallization, or scaling reducing gas-liquid contact area; airflow exceeding design value, high gas velocity, or insufficient contact time; abnormal demisting and wastewater discharge. Regularly test the circulating liquid's pH and density, promptly replenish alkali and replace water, clean and clear nozzles and packing, and verify if the actual airflow exceeds the design. When the single-stage tower is insufficient for high-concentration exhaust gas, increase the number of spray stages or use two-stage towers in series. Do not rely on indefinitely increasing alkali concentration as a solution.

The travel time of a damper actuator is related to its torque specifications. Low-torque, fast models can complete their full cycle in just seconds, while high-torque models require longer times due to their higher gear reduction ratios. Generally, the greater the torque, the slower the travel time, which is a normal design principle. When selecting, under the condition that torque requirements are met, interlocked and emergency dampers should preferably be chosen with shorter travel models. If an actuator of the same specification operates noticeably slower, it is often due to jamming in the damper shaft seat, valve vane wall friction, excessive sealing pressure, or low power supply voltage. Mechanical load should be checked first instead of assuming actuator failure.

Torque depends on the wind area of the valve vane, the pressure difference before and after the valve, the friction resistance between the vane and the shaft seat, the sealing pressure, and the safety factor. Generally, larger diameters, higher wind speed and wind pressure, and more vanes require greater torque; soft-sealing valves need to overcome the sealing ring pressure, and multi-leaf valves need to sum the torque of each blade. The simplest and most reliable method is to provide the valve diameter, type (round valve or multi-leaf valve), wind pressure, and medium to the valve manufacturer, who will select and match the complete anti-corrosion actuator based on experience and calculations. When selecting independently, ensure sufficient torque margin, as insufficient torque can lead to failure to operate, stalling, or motor burnout.

Resistive mufflers perform well on mid-to-high frequency noise but have limited effectiveness on low-frequency noise due to the long wavelength of low-frequency sound waves, which are not easily absorbed by conventional thickness acoustic absorption materials. For fan noise dominated by low frequency or high noise reduction requirements, thickening the muffler plates, increasing the bulk density of the acoustic absorption material, extending the muffler length, or adopting impedance composite mufflers utilizing the reactive principles of expansion chambers and resonance chambers for low-frequency noise reduction can be considered. It is recommended to conduct a noise spectrum test on the fan first and then design the muffler based on the spectrum to avoid selecting based solely on experience.

Spray Tower Accessories Prefer Vertical Tank-Immersion Pumps: They feature no shaft seal, resistance to acid and alkali corrosion and leakage, allow brief dry running, reliable submergence suction, and occupy no floor space, making them ideal for unattended continuous operation of exhaust towers. The advantage of horizontal corrosion-resistant pumps is the convenience of ground-level maintenance during repairs without lifting, suitable for applications where tank tops cannot be opened, high pump power is required, or ground-level maintenance is the local practice. Selection should consider tank structure, site conditions, medium temperature, and maintenance requirements. In cases with strong corrosion and concerns about seal leakage, vertical shaftless pumps are more reliable.

Displacement control (also known as window opening control) indirectly calculates the required air volume based on the window opening, offering fast response and lower cost. However, it assumes that the face velocity is solely related to the window opening and cannot compensate for air volume changes caused by factors such as filter blockage or fan aging. Face velocity control directly installs a face velocity sensor at the window for closed-loop regulation based on actual face velocity, providing more direct and higher safety control. However, the sensor is located in the contaminated area, requiring regular cleaning and calibration. High-standard laboratories can adopt face velocity control or a combination of displacement control with air volume measurement, with the specific choice determined based on safety level and budget.

The activated carbon adsorption tower is primarily used to treat various organic waste gases and odors, such as benzene, toluene, xylene, and other aromatic compounds, aldehydes, ketones, esters, and other organic volatile organic compounds (VOCs), as well as odorous waste gases generated in industries like food processing and wastewater treatment. For acidic or alkaline waste gases and those with high dust content, it is recommended to install a spray tower for pretreatment before the activated carbon tower to remove acidic or alkaline components and particulate matter, preventing pore blockage of the activated carbon and extending its service life. For high-concentration organic waste gases, it is recommended to adopt a combination of processes such as rotary concentrator or catalytic combustion for treatment.

Both are wet exhaust gas purification equipment, but their internal structures and applicable conditions differ. Standard spray towers rely on a packing layer to increase gas-liquid contact area, suitable for conventional acid-base waste gas and acid mist treatment, but viscous waste gas and dust can easily cause packing blockage. Cyclone towers utilize centrifugal separation generated by multi-layer swirling vanes and liquid film adhesion to remove dust, making them more suitable for viscous exhaust gas such as paint mist and conditions with higher dust content, and less prone to blockage. Cyclone towers have relatively higher resistance, requiring matching fans with higher pressure when selecting.

The main differences lie in the manufacturing process and applicable scenarios. Formed ducts are produced using an extrusion process, resulting in uniform wall thickness, smooth inner surfaces, low air resistance, and high production efficiency, making them suitable for standard specifications and large-volume production. Machined ducts are fabricated from PP flame-retardant sheets through welding, with flange reinforcement, making them ideal for large diameters, non-standard dimensions, and special-shaped ducts. They offer high flexibility but relatively lower production efficiency. Both materials are corrosion-resistant and acid/alkali-resistant. Standard branch ducts are recommended for formed ducts, while large-diameter main pipelines are suitable for machined ducts.

The PP elbow is primarily designed for spigot connection, where the spigot end of the elbow is inserted into the end of the PP ductwork, or the ductwork is inserted into the spigot of the elbow. It is sealed with sealant or a seal ring, offering easy and flexible installation, suitable for small and medium pipe diameters. For large-diameter pipelines, the flange connection method can be used. Flange plates are welded to both ends of the elbow, and the ductwork flanges are connected with bolts and sealed with gaskets, providing excellent sealing performance and secure connections. During installation, ensure proper insertion and good sealing to prevent exhaust leakage. The specific connection method should be selected based on the pipe diameter and pressure.

The main differences lie in the manufacturing process and applicable scenarios. Fabricated ducts are welded from PP sheet material with flange reinforcement, suitable for large diameters, non-standard sizes, and special-shaped ducts, offering high flexibility but relatively lower production efficiency. Formed ducts employ extrusion technology for one-piece molding, featuring uniform wall thickness, smooth inner surface, and low air resistance, making them ideal for standard specifications and mass production. Both materials are corrosion-resistant and acid/alkali-resistant. Large-diameter main ducts are typically selected for fabricated ducts, while standard branch ducts are chosen for formed ducts. The two can be used together to form a complete ventilation system.

Mainly handles various acid, alkali, and acid mist exhaust gases, such as sulfuric acid mist, hydrochloric acid mist, nitric acid mist, alkali mist, and chromic acid mist. It can also be used for pre-treatment cooling, dedusting, and demisting of organic exhaust gas before entering activated carbon or catalytic combustion equipment. For viscous exhaust gas with more paint mist and dust, it is recommended to choose a swirl tower structure, utilizing the centrifugal separation generated by swirl vanes and the adhesive effect of liquid film to remove particulate matter. The absorption liquid needs to be matched according to the pollutant composition, such as using alkaline solution to absorb acidic gases and acidic solution to absorb alkaline gases. For high-concentration exhaust gas, multi-stage series treatment can be adopted to ensure compliance at the outlet.

Xicheng Environmental Protection's permanent magnet energy-saving fans adopt advanced permanent magnet frequency conversion technology, with significant advantages such as high efficiency and energy saving, stable operation, low noise, and long service life. They are developed through industry-university-research cooperation with universities including Xi'an Jiaotong University and Tongji University.

两者区别主要在耐腐蚀等级，304 能满足一般酸碱、油雾和常规腐蚀工况，用量较大。316L 添加了钼元素，耐氯离子点蚀和缝隙腐蚀能力更强。它更适合含氯气体、盐雾、海边环境以及腐蚀更重的场合。选型时要先弄清废气的氯离子含量、酸碱种类、浓度和温度，再确定牌号。不能只看初期造价，牌号偏低会导致塔体早期腐蚀，带来停机和更换损失。成分复杂或拿不准时，应提供化验数据由技术人员判断，不必盲目堆高牌号。

The V0 PPs board is made by adding a flame retardant system to polypropylene, with the main material still being PPs. Its acid, alkali, and salt corrosion resistance performance is basically comparable to that of ordinary PPs, and it can handle general acid and alkali mists and organic exhaust gases without issues. However, some strong oxidizing agents or high-concentration special organic compounds may affect the material or flame retardant components. When treating complex mixed exhaust gases, the manufacturer should be provided with the gas composition, concentration, and temperature to verify material compatibility, and immersion testing may be necessary if required. When selecting materials, attention should be paid to both the flame retardant test report and corrosion resistance applicability—neither should be considered in isolation.

Required. V0 Flame Retardant addresses the issue of the duct material itself being difficult to ignite and not spreading flames, which falls under material fire protection. Fire dampers are fire separation measures for ventilation systems. In cases where ducts pass through fire compartments, machine room partition walls, or floors, they automatically close to block smoke and fire from spreading through the ducts during a fire, which belongs to system fire protection design. The functions of the two are different and they cannot be mutually replaced. Whether to install fire dampers, their installation locations, and temperature ratings must be implemented in accordance with building fire protection design codes and fire review opinions, determined by the design unit. Fire dampers cannot be omitted simply because the duct is V0 flame retardant.

Yes. Although the SDG process does not have water and scaling issues, if the exhaust gas contains dust, oil mist, or a large number of droplets, dust will adhere to the filter media surface, and liquid droplets will cause the filter media to become damp and cake, leading to increased resistance and uneven airflow distribution. Therefore, dust removal, oil removal, and fog removal pretreatment should be performed before the gas enters the cabinet to maintain relatively dry and clean exhaust gas. If the pressure differential rises, first check whether the pretreatment filter media has failed or whether the filter media surface has accumulated dust. Clean or replace the surface filter media if necessary. Proper pretreatment and airflow distribution are key to extending the service life of SDG filter media and preventing blockages.

PVC flexible connectors will gradually age under long-term exposure to vibration, ultraviolet light, temperature fluctuations, and corrosive gases,Manifested as tubing wall hardening and yellowing, loss of elasticity, crack formation, whitening at wave patterns, and even cracking or air leakage. Replace the connector promptly if it becomes hard, damaged, or if the clamp area tears, or if vibration isolation performance declines or abnormal shaking occurs. Flexible connectors have a longer service life in indoor moderate-temperature corrosive environments, but their lifespan is significantly reduced under outdoor exposure to sunlight, near high-temperature pipelines, or in highly corrosive environments. Consider adding shading measures or selecting weather-resistant and temperature-resistant materials for flexible connectors. During routine inspections, check for signs of collapse, bulging, cracking, or loose clamps on the connector, and replace aging components regularly during fan maintenance. As flexible connectors are wear parts, it is recommended to keep a small stock based on pipe diameter, allowing for immediate replacement upon issue to prevent vibration damage to ductwork and equipment after vibration isolation failure.

Whether flammability is required depends on the fire protection requirements of the installation location. Standard PVC has a certain self-extinguishing property, but this does not equate to an engineering flammability rating and cannot be used in concealed spaces with clear fire safety requirements. When installed in indoor suspended ceilings, pipe shafts, crowded areas, or high fire protection requirement zones, it is essential to explicitly require flammable materials and review test reports. In such cases, selecting flammable PPs dampers is generally more reliable. For underground spaces, laboratories, high-rise buildings, and exhaust systems crossing fire compartments, it is recommended to select flammable dampers according to design specifications. Outdoor open, non-fire-rated general corrosive exhausts can use standard materials. The specific material should be determined based on building fire protection design and local review requirements. The material's combustion performance rating must be noted in drawings and purchase orders to avoid substituting standard materials with flammable products on-site.

Horizontal airflow in Horizontal Tower causes liquid droplets to fall perpendicular to the airflow due to gravity. If the tower's air velocity is too high and the spray rate is excessive, liquid carryover at the outlet is more likely. Design-wise, controlling the horizontal air velocity below the empty tower velocity of the vertical tower, providing sufficient gas-liquid separation space between the spraying section and the outlet, and installing baffle plates or filler demisting sections at the gas outlet can effectively dehydrate. During operation, if liquid carryover is detected at the outlet, check whether the air volume exceeds the design value, whether the demister is blocked or damaged, and whether the spray is excessive. Clean the demisting section promptly and adjust the operating parameters back to the design range.

The plate thickness should be comprehensively determined based on equipment dimensions, pressure-bearing requirements, and installation location; it is not necessarily more reasonable to use thicker plates. Coiled round ducts typically use thin plates, while tower cylinders are selected based on diameter using medium-thick plates. Only liquid-containing tanks and load-bearing bases require thicker plates. During selection, calculate the required wall thickness based on working pressure, medium density, and stiffener layout. Strength and stiffness meeting the requirements are sufficient. Excessive thickness not only increases material costs but also adds to equipment self-weight, coiling difficulty, and welding workload, ultimately reducing overall cost-effectiveness. Thin plates combined with a reasonable strengthening structure are often more economical than blindly increasing thickness. If uncertain, provide equipment diameter, height, and medium conditions, and the design or manufacturer can offer thickness recommendations based on experience.

PPs sheets should be stored on flat and solid ground or shelves, ensuring even distribution of weight to prevent localized suspension that may cause long-term bending and deformation of the sheets. Thick sheets should be placed flat and stack height controlled to avoid compression and warping of lower layers. Storage environment should be away from open flames and high-temperature heat sources, maintaining dryness and ventilation to prevent surface aging, discoloration, and performance degradation due to prolonged sun exposure. The protective film on the sheet surface should be removed before processing to minimize scratches and contamination during handling and cutting. Sheets should not be stored with oil stains, solvents, or sharp metals. During handling, lift and place gently to avoid dragging. In winter, when low temperatures reduce the material's toughness, sheets should be warmed indoors before bending or coiling to minimize the risk of brittleness.

The opening area of the fume hood's door continuously changes as it moves vertically; to maintain a constant face velocity at the door, the exhaust airflow must vary continuously with the door opening. On/off valves can only be fully open or closed and cannot track the continuous airflow demand; analog valves can continuously adjust their opening under controller commands, forming a closed loop with the door displacement or face velocity sensor to adjust the exhaust airflow in real-time, ensuring the face velocity remains stable within a safe range, preventing harmful substances from escaping while avoiding the energy waste of constant airflow operation in fixed airflow systems.

On-site simple inspection can be performed after the fan shutdown: observe if the valve disc seats fully, if the seal ring fits uniformly on the valve seat, and check for any air leakage sound or airflow sensation; under conditions, release tracer smoke on one side of the valve or use a manometer and anemometer to detect post-valve leakage. Quantitative acceptance can involve testing the air leakage rate of the valve section using air duct leakage detection methods and comparing it with the manufacturer's committed leakage level. During inspection, focus on checking for foreign matter, aging, or deformation in the seal ring, whether the valve shaft is horizontal, and if the petals of multi-leaf valves return synchronously.

When adding solid agents (such as caustic soda, soda ash) which require dissolution, where the liquid solution tends to precipitate, or when a uniform concentration throughout the entire drum is required, a top-mounted agitator should be used to accelerate agent dissolution and prevent active ingredients from settling at the bottom of the drum. For using finished liquid agents with uniform concentration and small dosage, an agitator is not necessary; manual stirring or circulation pump backflow stirring can be used instead. The power, impeller type, and rotation speed of the agitator should be selected based on the drum volume, liquid properties, and dissolution rate. The rotation speed should not be too high to avoid air entrapment, splashing, and drum wall damage. Even with an agitator installed, the solution should be stirred evenly before re-adding agents after long-term static storage, and the corrosion resistance and sealing condition of the impeller and shaft should be checked. The material of the agitator must be corrosion-resistant to the matched liquid agent, and leakage prevention measures should be taken at the shaft seal. During operation, the agitator's effectiveness should be monitored in conjunction with liquid level and concentration checks.

High resistance in tees should first prioritize the use of inclined tees, allowing branch pipes to connect along the main pipe airflow direction while controlling the angle between the branch pipe and the main pipe to avoid excessive angles, generally using acute-angle Bevel . Additionally, flow guides can be installed inside the tee to smoothly merge the two airflow streams, preventing the branch pipe's airflow from directly opposing the main pipe's incoming flow. Properly configure branch pipe dampers for airflow balance to prevent excessively high branch pipe velocities, entrainment, and backflow. The diameter reduction transition in reducing tees should be gradual to avoid sudden contractions. During installation, ensure the tee orientation is correct with the inclined end facing the airflow, smooth welding seams on the inner wall without weld ridges. These measures can significantly reduce the local resistance of the tee; if the system resistance remains high, consider appropriately increasing the main pipe or branch pipe diameter or reducing the internal pipe velocity.

The ability of circular ducts to withstand negative pressure is directly related to wall thickness, diameter, and the spacing of reinforcement rings. The larger the diameter and the higher the negative pressure, the more wall thickness needs to be increased, and the reinforcement rings on the outer wall need to be densified. Otherwise, the tube wall may be sucked and deformed under negative pressure. During design, the wall thickness and reinforcement ring spacing should be verified based on the total pressure of the fan and the negative pressure at various points in the pipeline. The negative pressure is the highest at the fan inlet section, which should be given special attention. For large-diameter pipe sections, the spacing of supports and hangers should also be controlled to prevent deformation of the pipeline under its own weight and negative pressure. Selecting an experienced manufacturer to configure wall thickness and reinforcement structure according to the negative pressure level can fundamentally avoid collapse issues. If concave deformation, abnormal sounds, or airflow anomalies are detected in the tube wall after operation, the machine should be shut down to inspect the reinforcement rings and wall thickness. If necessary, the weak sections should be reinforced or replaced.

Outdoor suspended ducts have a relatively low risk of fire spread, and the use of flame-retardant materials primarily depends on local fire codes, building spacing, and owner requirements. However, ducts in indoor spaces, suspended ceilings, crowded areas, and fire compartments typically require the use of flame-retardant materials. The main issues for outdoor ducts are ultraviolet degradation and temperature resistance; UV-resistant panels or sun shading and painting treatments should be selected to slow down plastic aging. For systems connecting indoors and outdoors, the pipe sections entering the building should comply with indoor requirements, using PP flame-retardant dampers and ducts. It is not acceptable to use standard materials for the entire pipeline just because the initial section is outdoors. When selecting materials, determine them based on the actual installation location of the dampers: outdoor sections should prioritize weather resistance, while indoor sections should prioritize flame retardancy. Fireproof sealing and fire dampers must be used when passing through building exterior walls and fire compartments.

With a large radius of curvature, the airflow transition is smooth, resulting in low resistance and noise, but the elbow occupies more space and consumes more materials. With a small radius of curvature, the installation is compact and material-saving, but the airflow transition is abrupt, leading to increased resistance and noise. When space permits, using a larger radius of curvature is beneficial for energy saving and reducing fan load. When space is limited, small-radius elbows can be used, and the resistance can be compensated by adding guide vanes. In engineering practice, the radius of curvature is typically selected as a certain multiple of the duct side length to balance installation space and system resistance, avoiding an exclusive pursuit of either large or small radii. For high-speed, high-capacity duct sections and elbows near the fan, the radius of curvature should be prioritized. Low-speed branch ducts can be appropriately reduced. During selection, the layout space, air velocity, and noise reduction requirements should be comprehensively considered, and resistance calculations may be necessary for critical elbows when required.

The weld seams and flange lengths of square tubes are typically longer than those of round tubes with the same cross-sectional area. If the processing and installation quality are the same, there may be slightly more potential air leakage points. However, as long as the four-corner longitudinal seams are continuously welded through, the flanges are flat, the gaskets are intact, and the bolts are tightened diagonally evenly, the air leakage rate can still be controlled within the design requirements. The key to controlling air leakage lies in the processing and welding quality, as well as flange sealing, rather than the cross-sectional shape itself. For negative pressure systems with high air leakage requirements, the weld seam appearance inspection and flange tightening acceptance should be strengthened, and air leakage testing should be conducted in sections if necessary. The rigidity of rectangular flanges is relatively weaker, so care should be taken during tightening to prevent flange warping, which could cause local gaps. After installation, combine system commissioning to inspect the flanges, weld seams, and openings, and promptly repair leaks by welding or replacing gaskets. The overall sealing performance of square tubes can meet the requirements for corrosion-resistant ventilation.

Valves installed in suspended ceilings are difficult to operate and maintain. During installation, inspection openings must be reserved at corresponding positions for the handle, linkage rod, and actuator. The valve shaft orientation and handle orientation should allow for easy operation and observation from the inspection openings. For electric valves, space must be reserved for power supply, control cables, and actuator heat dissipation. Valves must be securely connected to air duct flanges with proper alignment to prevent flange misalignment and air leakage caused by ceiling settlement. It is recommended to select valves with sealed vanes for suspended ceilings to reduce concealed air leakage points. Before commissioning, air flow adjustment must be completed, and the valve position must be marked on the valve body and drawings. During construction, valves should not be installed tightly against beams, slabs, or other pipelines to ensure sufficient space for handle operation and actuator assembly/disassembly. Before closing the ceiling panels, the valve installation, wiring, and commissioning must be inspected to prevent inoperability and difficulty in maintenance after panel closure.

If the actuator does not move or the motor is overloaded, common reasons include: the actuator torque selection being too small, the valve shaft being jammed due to dust accumulation and crystallization, the valve disc being stuck by foreign objects, the valve shaft and actuator being misaligned, the valve body deforming due to heat causing the valve disc to rub against the wall, and the limit switch position being improper causing the mechanism to jam. The actuator should be selected with sufficient margin based on the valve disc's aerodynamic torque, keep the valve shaft sealing area clean, align the valve shaft and actuator, and manually rotate the valve disc to ensure full flexibility before powering on for debugging. Prolonged overload will burn out the motor; it cannot be resolved by forcibly increasing the power supply or short-circuiting the overload protection. In case of an overload alarm, power off and troubleshoot mechanical issues first, address jamming and deformation, and then restart operation. If the valve itself has excessive torque, replace it with a higher torque actuator or reduce the valve disc and increase bearings to fundamentally eliminate overload.

The inlet and outlet diameters of the fan are determined based on the fan series and often do not match the selected duct diameters in the design. Transition pieces (reducers) are required to smoothly connect the fan interface with the duct. The inlet typically uses a conical or eccentric reducer to ensure uniform and symmetrical airflow into the impeller, preventing swirl flow-induced vibration, noise, and efficiency degradation. The outlet commonly employs an expanding reducer to decelerate high-speed airflow and increase pressure, reducing exit dynamic pressure loss. Transition pieces are typically used in conjunction with flexible connectors: reducers handle alignment and transition, while flexible connectors isolate vibration, forming the standard combination for fan piping installations. During installation, the length and orientation of the transition piece must comply with the manufacturer's piping requirements, and the inlet should be avoided with sharp bends or swirl flow. Proper fan inlet and outlet transition design maximizes fan performance, whereas improper design can result in airflow and pressure failing to meet design specifications.

During the hot melt welding of polypropylene, the gun temperature must be controlled within the range where the material is fully melted without carbonization. The actual setting should be adjusted based on the plate thickness, ambient temperature, and welding rod specifications. Higher temperatures are used for thick plates and winter construction, while lower temperatures are used for thin plates and summer conditions. If the temperature is too low, the welding rod and base material will not fuse properly, resulting in incomplete welding, cold joints, and leakage. If the temperature is too high, the material will carbonize and turn yellow, the weld joint will have porosity, and the plate may even be burned through. Before the actual welding, test weld using scrap material of the same material to observe the melting state of the welding rod, the luster of the molten pool, and the weld formation. Determine the appropriate temperature and gun travel speed before welding the final weld. Maintain stable parameters during welding and avoid frequent temperature adjustments. If the weld turns yellow, immediately lower the temperature. If incomplete welding occurs, grind it off and reweld.

Follow the sequence to troubleshoot: First, confirm that the power voltage matches the actuator nameplate, check if the control signal and valve opening command are present, and verify if the interlock conditions are met; then inspect if the connection between the actuator and valve stem is loose, and if the manual or electric switch is in the disengaged position; next, loosen the actuator's manual handwheel to determine if the valve disc is mechanically jammed or if the actuator itself is faulty. Mechanical jamming is often caused by dust and crystallization in the shaft seat, foreign objects stuck in the valve disc, shaft misalignment, or thermal deformation of the valve body, while electrical faults are typically related to the motor, limit switch, capacitor, or wiring issues. Do not repeatedly force power-on before identifying the cause to avoid burning out the actuator motor. After confirming the mechanical part is flexible, test the actuator with power-on alone to distinguish between mechanical and electrical faults before proceeding with repairs. After completing the repairs, perform several full open/close cycles to verify that the valve position feedback matches the actual opening degree.

The inner diameter of the sleeve socket is designed according to the standard outer diameter of the ductwork. As long as the outer diameters of the two connected sections of ductwork are consistent, even with slight variations in wall thickness, they can generally be spliced together. However, significant differences in wall thickness can result in one end being too loose and the other too tight, affecting alignment and weld quality. Excessive looseness can also increase the amount of welding filler required. The outer diameter tolerances of ductwork from different series or manufacturers may vary. Purchasing matching ductwork and sleeve sockets from the same manufacturer ensures better dimensional fit. When the outer diameters are inconsistent, do not force the connection, as misalignment and stress can cause air leakage. Instead, replace with a matching sleeve socket or use machined parts or flanges for transition. Standardizing the outer diameter standards and tolerances of ductwork during ordering can prevent mismatched connections on-site.

Most temperature-regulating plastic welding guns feature a replaceable heating core. To replace it, first power off and allow the gun body to cool completely. Then, remove the outer casing screws, disconnect the wiring terminals of the old heating core, install the new one, and restore it as before. When replacing, use a heating core of the same model and power specification. Ensure the wiring terminals are securely connected, the heat insulation and sealing components are properly reset, to prevent air leakage or excessive heat buildup on the casing. After assembly, perform an empty-load test run to check if heating, temperature regulation, and airflow are normal before putting it into welding. If the fan motor and temperature control circuit are both damaged, or the gun casing is aging, deformed, or exhibits reduced insulation, it is recommended to replace the entire unit to avoid temperature control failure after repair, which could lead to overheating and fire hazards. When in doubt, it is safer to leave the repair to professionals.

Common reasons for the handle not turning include dust and crystallization jamming at the valve shaft, deformation of the shaft seat due to heat or stress, the valve disc being stuck by foreign objects, misalignment between the valve stem and valve body, and excessive operating torque in large-diameter valves due to the lack of bearings. After shutdown and power-off, inspect the valve shaft and valve disc, remove crystallization and foreign objects, apply appropriate lubrication at the shaft seat, and correct the shaft alignment before slowly turning the handle. Large-diameter air valves should be selected with bearing structures to reduce rotation resistance. In highly corrosive environments, uncoated metal shaft sleeves should not be used to avoid rust and jamming; plastic shaft sleeves or metal components with corrosion protection coatings can be selected. If jamming persists after treatment, check if the valve disc is deformed and rubbing against the wall, or if the actuator is properly matched. In such cases, replace bearings or the valve if necessary, and strictly avoid using force pipes for Forceful manipulation .

Small observation windows are primarily used for observation, lighting, and sampling. After removing the observation panel, hands or tools can be inserted for simple inspection and cleaning, but they cannot replace standard manholes for personnel entry and exit. When personnel need to enter towers or inspect and repair boxes, they should use manholes that meet safety requirements in size and follow confined space work procedures, including ventilation, gas detection, and dedicated supervision. The openings of observation windows are typically small, and flanges and covers are not designed to support personnel loads. Forcing them to serve as entry/exit points will damage the equipment and pose safety risks. A few large-sized observation windows, if designed and manufactured with manhole standards in mind from the outset, considering opening size, flange strength, and sealing, can be used for both inspection and entry/exit. However, this falls under the category of observation manholes and requires specific specification during selection. Under standard configurations, observation windows and inspection manholes should be separately installed.

Strict directional requirements apply. The arrow or directional indicator on the valve body must align with the forward airflow direction, and the valve shaft must be installed horizontally to allow the valve disc to smoothly settle onto the seat under its own weight. Check valves for horizontal and vertical pipelines have different structures and cannot be interchanged: horizontal pipes require swing check valves, vertical upward pipes require vertical check valves, while vertical downward and horizontal downward airflow scenarios require the corresponding types. Incorrect installation can prevent the valve disc from opening properly, causing air restriction and fan overload, or result in failure to close and loss of check function. After installation, manually operate the valve disc to verify correct swing direction, smooth reseatment, absence of sticking or abnormal wear. The valve shaft levelness and the clearance between the valve disc and seat must also be checked. Any directional or levelness issues must be adjusted before operation.

The closed valve should be installed close to the inlet and outlet of the equipment or pipe section to be isolated, minimizing the isolated area. The valve position should be convenient for personnel to operate, observe, and lock, avoiding installation in hard-to-reach locations. When equipment maintenance is required, two closed valves can be installed before and after the equipment to form dual isolation. If necessary, a vent or inspection port can be provided between the two valves to ensure reliable isolation of the maintenance section from upstream and downstream. The valve should be installed according to the airflow indicator on the valve body, so that the positive pressure in the pipeline after closure helps to press the valve disc toward the seat, enhancing the seal. Fixed supports should be installed before and after the valve to prevent the valve body from experiencing cantilever stress deformation after disassembling adjacent equipment, which may affect the seal surface contact. For valves used to isolate hazardous gases, a full-closure air leakage check should be performed after installation, and the operating position and open/close status should be clearly marked and included in on-site safety management.

The height of the packing layer is determined based on the inlet concentration of pollutants, the required purification efficiency, and the mass transfer performance of the packing itself. The higher the inlet concentration and the stricter the emission requirements, the more mass transfer units are needed, and the taller the bed becomes. Packing height is not always better; excessive bed height increases bed resistance and fan energy consumption. When liquid distribution is poor, wall flow and channel flow occur, further increasing packing height offers limited efficiency improvement. In engineering practice, the total height is often divided into several sections, each controlled within a reasonable height, with liquid redistributors installed between sections to evenly distribute liquid flowing down the walls across the cross-section. Design calculations determine the height of each section and the total height based on material balance and gas-liquid mass transfer, with a certain margin reserved. Once determined, the number of packing layers should not be arbitrarily added or removed on-site. If adjustment is necessary, it should be based on recalculations considering measured resistance and outlet concentration.

The tread is fixed to the lower support or beam via Overlapping edge and plastic fasteners. The panels overlap and constrain each other, ensuring that the installation, when properly executed, prevents the tread from warping under normal foot traffic. The key is to ensure the support spacing aligns with the tread's allowable span. The fasteners must be installed correctly and in full quantity, with edge and end fastening on both sides of the walkway to eliminate free edges. If the support spacing is too far apart, causing the tread to sag, or if fasteners are missing or loose, warping, sliding, and abnormal noises may occur during walking. In such cases, additional supports and fasteners should be installed. During installation, first secure the support beams and level them, then lay the panels one by one, securing each as it is placed to prevent any panels from Suspended . After installation, inspect the fasteners and Splice for tightness. Address any looseness or missing fasteners promptly to maintain a flat panel surface and prevent tripping hazards due to warping.

Either method can be used, determined by whether disassembly is required for specific sections. For fixed pipe sections that are rarely disassembled, the air damper socket can be welded directly to the duct, ensuring good weld seam sealing, saving flanges, maintaining continuous corrosion protection, and reducing costs. For sections requiring maintenance, disassembly, or where the vane or seal may be replaced, flange connections are recommended. The flanges at both ends of the valve are secured with gaskets and bolts, allowing for easy assembly and disassembly without damaging the pipeline. It is recommended to use flange connections with flexible connections at the fan inlets/exits and near equipment for convenient equipment maintenance and vibration isolation. In actual projects, main fixed sections are typically welded, while flanges are used at both ends of equipment, fans, and valves requiring maintenance. Regardless of the method, ensure the valve body is coaxial with the pipeline and the vane rotates without interference. Avoid high temperatures during welding that could damage the vane and seals.

The clearance exists between the vanes of a conventional multi-leaf valve and between the vanes and the valve body, resulting in air leakage even when fully closed. This is a normal characteristic of regulating valves and cannot be measured by the requirements of a sealed valve. If the air leakage increases significantly compared to before, it is necessary to check whether the sealing strips on the vane edges are aging or falling off, whether all vanes are aligned synchronously, whether there are any Miscellaneous Items in the valve body, and whether the vanes are deformed or warped. After cleaning the Miscellaneous Items , aligning the synchronization, and replacing the failed sealing strips, the air leakage generally returns to normal levels. For applications requiring higher gas tightness, an enclosed multi-leaf valve with soft sealing strips on the vanes and side sealing at the ends should be ordered, along with a handle, worm gear, or actuator capable of providing sufficient closing force. When ordering valves for isolation maintenance, the gas tightness specifications must be clearly defined at the time of ordering, and they cannot be replaced with conventional regulating valves afterward.

Ceiling plenums and indoor fire compartments typically require fire-resistant duct materials. Standard PP lacks fire resistance and should be replaced with fire-resistant PP electric square dampers and fire-resistant rectangular ducts, meeting the fire code's material combustion performance requirements. Standard PP electric square dampers are more suitable for outdoor, open workshops, or corrosive exhaust applications without fire resistance requirements. Whether fire-resistant materials must be used depends on the building fire design, duct installation location, and local review requirements. Material selection should not solely consider corrosion resistance. Dampers installed in ceilings, pipe shafts, vertical shafts, and high-traffic areas should generally be configured with fire resistance. When ordering, specify the material and fire resistance grade in the list and request a test report to prevent the use of standard materials as substitutes for fire-resistant products on-site.

A single-stage packed tower has its absorption capacity limit. When the exhaust gas concentration is high, the required removal efficiency is high, or the solubility of pollutants is low, the gas-liquid contact time and mass transfer stages are insufficient, and a single tower cannot meet the standards. In engineering, two-stage packed spray Series , increasing the packing height and spray volume, or increasing the liquid-to-gas ratio can be adopted. Intermediate circulation can be set between the two stages of the tower to allow pollutants to be absorbed step by step. Whether multiple stages are needed should be determined by designers based on material balance and absorption calculations, and cannot be simply scaled up from a single tower. High concentration and fast-reacting gases can be handled with a single stage, while difficult-to-absorb or strictly regulated emissions often require multiple stages.

When the fan has a circular interface while the connected ductwork is rectangular, a square-to-round shape conversion is required; if both the fan interface and the ductwork are circular, a reducer with a flexible coupling can be used without a square-to-round conversion. In actual engineering projects, when indoor rectangular ducts connect to circular roof or machine room fans, a combination of square-to-round conversion, flexible coupling, and reducers is often employed: the square-to-round conversion handles shape transformation, the flexible coupling isolates fan vibration, and the reducer addresses diameter differences. Whether to use a square-to-round conversion depends on whether the fan interface and duct cross-sectional shape are consistent. During layout, try to place the square-to-round conversion near the fan with smooth transitions to ensure uniform airflow. Before ordering, verify the fan interface dimensions and duct cross-sectional dimensions to ensure this set of transition fittings can be matched in one go, reducing on-site duct modifications.

Diameter selection should balance purification efficiency, bed resistance, and tower diameter compatibility. Small balls have a larger specific surface area, ensuring thorough gas-liquid contact and high efficiency, but with relatively smaller voids, higher resistance, and a greater tendency to be clogged by dust and crystallization. Large balls offer larger voids, better anti-clogging performance, and higher throughput, but with a smaller specific surface area per unit volume and slightly lower efficiency. For clean gas and high purification requirements, choose smaller balls; for dusty, sticky, or low-pressure drop, high-flow scenarios, select larger balls. The ball diameter should maintain a reasonable ratio with the tower diameter. If the tower diameter is too small while the ball diameter is too large, severe wall and channel flow will occur, concentrating gas and liquid near the tower wall, significantly reducing the effective mass transfer area. In the same tower, smaller balls can be installed in the upper section, while larger balls in the lower section, with the lower section providing anti-clogging performance and the upper section for fine treatment. After determining the ball diameter, calculate the packing height, support grille openings, and plate gaps accordingly.

When the fluid contains suspended solids, crystals, adhesives, or fibers, the small holes of the porous plate may gradually become clogged, leading to increased resistance, reduced flow rate, and uneven distribution. The appropriate hole size and type should be selected based on the cleanliness of the medium. Fibrous or easily crystallizing media should preferably use long-round holes, slot holes, or larger hole diameters to reduce the probability of bridging blockage, and reverse flushing or regular cleaning measures should be implemented. Porous plates in exhaust towers can be regularly flushed with spray water to remove plate surface crystals and dust; sieve plates in the tank should be designed as removable and detachable structures for easy periodic removal and cleaning. During operation, blockage severity can be determined by pressure drop or flow rate changes, and cleaning should be scheduled when resistance continuously increases. If necessary, filtering or pre-washing should be added at the front end to reduce impurities entering the porous plate, extending the cleaning cycle from the source.

Sealing ring failure manifests as significantly increased air leakage after full closure, audible air leakage from the valve body, and abnormal changes in closing torque. Causes include normal aging, swelling from corrosive gases, wear from dust crystallization, high-temperature deformation, and permanent deformation from prolonged tightening. Replacement cycles have no fixed value and depend on medium, temperature, and operating frequency, requiring determination through regular air leakage checks. Spare parts must be selected for corrosion resistance compatible with exhaust composition, and full-closure sealing uniformity should be rechecked after replacement.

Standard injection molded reducer covers common size combinations, with fast delivery and smooth inner wall; for special sizes, irregular interfaces, or non-standard equipment, PP sheet can be rolled and welded to produce reducers, which involves cone unfolding, cutting, rolling, and welding. Machined reducers offer high flexibility, capable of producing any size, length, and eccentricity, making them ideal for non-standard projects and on-site modifications. However, they have slightly lower appearance consistency and inner wall smoothness compared to injection molded parts, with a longer production cycle. Standard specifications are preferred for molded parts due to stable quality and fast delivery, while urgent, non-standard, and irregular transition parts should be considered for sheet processing. When custom machining, provide the port sizes, length, concentric or eccentric requirements, and connection method for one-time formation.

The baffle channel of the water collection plate features open design, low resistance, and is less prone to blockage, making it easy to clean. It is suitable for applications with larger liquid droplets, dusty or crystalline gas, and low resistance requirements, being the most common form. The packed (or mesh) channel has a dense structure and a large specific surface area, demonstrating strong collection capability for fine mist droplets and high mist removal efficiency. However, it has slightly higher resistance and is prone to blockage by fine debris, making it suitable for scenarios with fine droplets, low dust content, and high mist removal requirements. For high-demand applications, a two-stage combination of baffle plates and packing can be adopted, first removing large liquid droplets and then capturing fine mist, balancing anti-blocking and efficiency.

The material of the gasket should be selected based on the composition of the exhaust gas, temperature, and pressure. For general acid-base ventilation, acid-resistant and alkali-resistant rubber gaskets or EPDM rubber gaskets can be used, which offer good elasticity and low cost. For applications requiring higher temperature and corrosion resistance, PTFE gaskets or PTFE-coated gaskets should be selected. The thickness of the gasket must be uniform, and its dimensions should match the flange sealing surface. During installation, place the gasket centrally and install it in one go without offsetting. Multiple layers of gaskets should not be used to Accumulate thickness . For exhaust gas containing organic solvents, oils, or special media, verify the compatibility of the gasket material to prevent swelling, softening, and failure of the gasket. It is recommended to replace a new gasket each time a flange is disassembled. Reused aged gaskets are a common cause of air leakage. When ordering, ensure the corresponding specification gaskets are matched based on the flange nominal diameter and sealing surface type to avoid incorrect usage on-site.

Pressure control involves installing a pressure sensor on pipelines or equipment, where the controller automatically adjusts the speed of the permanent magnet motor based on the deviation between the measured pressure and the set pressure: the speed decreases when the valve closes or the air usage point reduces, and the speed increases when air usage increases, maintaining stable network pressure and avoiding waste caused by constant-speed operation and air valve throttling. The permanent magnet motor is powered and speed-controlled by a dedicated drive controller, which integrates startup, protection, and speed-control functions. Therefore, traditional complex distribution devices such as star-delta startup cabinets are not required, but must still be configured for power supply, protection, and grounding by electrical professionals in accordance with specifications. The selection of the controller and cable laying should meet the equipment electrical drawing requirements, and electrical inspections must be completed before commissioning.

Check both electrically and mechanically. Electrically, verify if the power voltage is normal, if control signals have arrived, if connections are loose, and if internal protection has been activated. Mechanically, disconnect the actuator and manually rotate the valve to determine if the valve shaft is jammed (due to dust crystallization, valve disc jammed by foreign objects, or valve body deformation) or if the actuator itself is faulty. After confirming the valve is flexible, inspect the actuator motor and limit switch. Do not repeatedly power on under mechanical jamming of the valve disc, as the motor may overheat and burn out due to jamming. In corrosive environments, also check if the terminal connections and housing are corroded.

Common reasons include: insufficient sound absorption capacity or mismatch between the sound absorption band and the noise spectrum; excessive flow velocity inside the duct generating airflow Recycled noise; vibration of the fan transmitted through the pipeline and supports as solid-borne sound, which is ineffective for mufflers; thin walls of the pipeline and exhaust stack behind the muffler being excited by airflow and transmitting sound; unsealed sound leakage bypasses. System analysis is required: controlling flow velocity, adding vibration isolation soft connections and hangers, soundproofing the exhaust stack, positioning the muffler near the radiation outlet, and redesigning the sound absorption capacity based on actual measured frequency spectra if necessary. Relying solely on adding one muffler to solve all noise issues is not effective.

It's not the same. They have different positions and functions. Grating plates are installed below the packing layer, primarily to support the entire packing layer, bearing the weight of the packing and the liquid retained. They require high load-bearing capacity and non-leakage openings. Packing support plates, also known as packing limit plates or packing screens, are installed above the packing layer. Their function is to prevent the packing from being blown, fluidized, or carried away by the gas flow at high gas velocities. They experience relatively lower stress, allowing for larger openings. The two work together in an upper-lower combination: the grating below supports the packing to prevent it from falling, while the plate above holds the packing in place to prevent it from floating. They are often installed together in packed towers operating under high gas velocities and large flow rates. When selecting, grating plates are determined based on load-bearing capacity and packing dimensions, while support plates are determined based on gas velocity and anti-carrying requirements. They cannot be mutually substituted. The installation sequence is first to lay the grating, then install the packing, and finally cover the support plate. The reverse sequence is used for maintenance.

Ventilation hoods with fixed sash openings and constant airflow rates are suitable for mechanical Venturi variable air volume (VAV) dampers, which offer low initial investment, no power supply requirement, and simple maintenance. For hoods requiring constant face velocity during sash sliding and reduced airflow when the sash is closed to save air conditioning fresh air energy consumption, variable airflow Venturi dampers are recommended. These dampers are equipped with actuators and controllers to dynamically adjust airflow based on sash displacement or face velocity signals. Modern laboratories with multiple hoods, long operating hours, and high energy savings requirements often use VAV systems. Budget constraints or limited cabinet space may make fixed airflow dampers a more suitable option.

Constant airflow fume hoods maintain a constant exhaust volume with a simple structure and low investment. However, when the viewing window is partially closed, the wind speed increases and energy consumption does not decrease, making them suitable for laboratories with a small number of fume hoods and low usage frequency. Variable airflow fume hoods adjust the exhaust volume by the displacement of the viewing window or through the linkage with venturi variable airflow valves, increasing the exhaust volume when the window is opened and decreasing it when closed, while maintaining a constant face velocity. This ensures safety and significantly reduces the energy consumption of air conditioning fresh air, making them suitable for modern laboratories with a large number of fume hoods, long operating hours, and energy-saving requirements. However, they require a higher initial investment and more stringent control and maintenance requirements.

No fixed cycle; it depends on the acid mist generation volume and the saturation level of the circulating liquid. In engineering practice, pH meters and salt concentration (density) are used for control: when the pH drops below the set lower limit, alkaline reagents are automatically added. When the salt concentration in the circulating liquid becomes excessively high, absorption efficiency decreases, or the discharge standard is reached, some or all of the circulating liquid is discharged and replaced with fresh water and fresh alkaline reagents. It is recommended to configure automatic pH dosing and regular discharge systems. Wastewater must be sent to a wastewater treatment facility and cannot be discharged directly. For manual management, pH and liquid level should be tested by shift, and records for reagent dosing and water replacement should be established to avoid long-term liquid replacement based on subjective judgment.

Under normal conditions, the worm gear reducer in the valve mechanism has a self-locking function, preventing the valve disc from being moved by airflow once positioned. The return of the valve disc is usually caused by: the actuator torque being undersized, the valve disc being impacted by pulsating airflow exceeding its self-locking capacity; loose fixing of the jaw plate to the valve shaft causing relative rotation; wear of the reducer leading to failure of self-locking; improper limit position preventing the valve disc from reaching its actual position. Check the jaw plate tightness and the actual position of the valve disc. For large-diameter high-pressure valves, select an actuator with higher torque and reliable self-locking function, and add mechanical locking if necessary. Avoid keeping the valve in a semi-open semi-closed state in vibrating airflow for extended periods.

For scenarios requiring only full open/close, remote on/off, and device interlocking of dampers, select the corrosion-resistant on/off actuator. It features simple control and low cost, with a typical power supply of 220V. For dampers that need continuous position adjustment based on signals, used in variable air volume ventilators, negative pressure control, and airflow balancing, select the corrosion-resistant analog actuator. Its typical power supply is AC/DC 24V, capable of receiving standard control signals and providing valve position feedback. When both on/off and regulating valves are present in the same project, they should be configured separately. Frequent on/off actuation for analog regulation is not recommended, as it may lead to inaccurate positioning and potential motor damage.

Attenuation level increases with length within a certain range, but not infinitely linearly, and length increase also raises resistance, occupies space, and increases cost. The attenuation level of resistive mufflers is approximately proportional to effective length, but high-frequency sound may be attenuated completely within the channel, rendering excessively long ends ineffective; there is also an upper limit failure frequency issue in inter-plate channels. In engineering, the required length is calculated based on target attenuation and octave bands, with segmented design generally being more economical and reasonable than single excessively long sections, determined by acoustic design.

The circulating liquid in the exhaust tower contains acids, alkalis, and salts, which will corrode ordinary cast iron and stainless steel pumps. Specialized pumps with PP, PVDF, FRPP, or other corrosion-resistant material impellers must be selected. Generally, PP or FRPP is sufficient for acidic/alkaline and ambient temperature circulating liquids; for media with higher temperatures, strong oxidizing properties, or special solvents, PVDF or higher-grade materials should be selected. When selecting, the composition, concentration, and temperature of the circulating liquid should be provided to the manufacturer to verify material compatibility. Additionally, attention should be paid to the corrosion protection of the motor and metal frame to prevent corrosion from tower area gases. Using the wrong material or substituting with ordinary fresh water pumps will lead to issues such as impeller corrosion and pump body leakage in the short term.

Honeycomb activated carbon features block状 straight-through pore channels, offering high surface area, low airflow resistance, minimal clogging, and neat installation, making it ideal for high airflow and low concentration organic exhaust gas. It is the most common form used in drawer-style carbon boxes. Granular activated carbon provides high adsorption capacity, lower cost, and can be bulk-filled, but has higher resistance and may cause channeling, suitable for low airflow, higher concentration, or frequently replaced applications. For special gases like acid and alkali, modified activated carbon impregnated with specific agents can be selected. Specific carbon types and iodine adsorption values should be determined based on pollutant types by design.

Most of the time, the sash of a fume hood is in the closed or slightly open position. The constant airflow system continuously exhausts air at maximum airflow regardless of the sash opening, often discharging air that has been conditioned by air conditioning, resulting in high energy consumption. The variable airflow system reduces the exhaust volume to a very low maintenance airflow when the sash is closed, significantly reducing the exhaust volume per hood. The VAV dampers of multiple fume hoods aggregate the airflow demand to coordinate the variable frequency drives of the exhaust and supply fans, thereby reducing the overall laboratory air conditioning and ventilation energy consumption. The more fume hoods there are and the longer the sash remains closed, the more significant the energy savings become, typically allowing the increased investment to be recovered within several years.

The drawer-type activated carbon adsorption box features a drawer-style tray design, allowing for convenient and quick loading and replacement of activated carbon without disassembling the entire unit. It is suitable for medium-low airflow applications requiring frequent activated carbon replacement. The fixed-type activated carbon tower has a large activated carbon loading capacity and a thicker adsorption layer, making it ideal for high airflow and continuous operation scenarios. Activated carbon replacement requires opening the maintenance door for operation. When selecting, factors such as treatment airflow, exhaust gas concentration, replacement cycle, and on-site maintenance conditions should be comprehensively considered. If unsure about the selection, field conditions can be provided for technical personnel to recommend the most appropriate structural form.

The cyclone tower is primarily used for treating paint mist, viscous exhaust gas, and dust-laden exhaust gas, such as paint mist exhaust gas in the coating spraying industry, dust-containing exhaust gas in the metal grinding and polishing industry, dust exhaust gas in the building materials and cement industry, wood dust and paint mist exhaust gas in the woodworking and furniture industry, and smoke and dust exhaust gas in the rubber and plastic industry. For conventional acid-base exhaust gas, a standard packed tower can be selected; for high-concentration or difficult-to-treat exhaust gas, a series configuration of cyclone tower and packed tower or a multi-stage cyclone tower combination process can be adopted. For exhaust gas containing organic pollutants, an activated carbon adsorption box can be connected in series after the cyclone tower for deep treatment.

PP ducting is primarily used for conveying corrosive gases and acid-base exhaust fumes, such as hydrogen chloride, hydrogen fluoride, ammonia gas, sulfuric acid mist, and other water-soluble gases, as well as organic exhaust fumes and dust exhaust fumes. The PP material is resistant to acid and alkali corrosion, making it suitable for exhaust gas transportation in industries such as chemical, electronics, and coating. For high-temperature gases, it is necessary to confirm that the temperature is within the temperature resistance range of the PP material; for gases with a high concentration of organic solvents, material compatibility should be evaluated, and alternative materials or additional protective measures should be selected if necessary.

The choice between 90-degree elbows and 45-degree elbows primarily depends on the pipeline layout requirements and the airflow pressure drop requirements. 90-degree elbows are used for right-angle turns in pipelines, featuring a compact structure and minimal space occupation, making them the most commonly used type suitable for confined spaces requiring right-angle turns. 45-degree elbows are used for oblique turns in pipelines, providing smoother airflow redirection and lower pressure drop, making them ideal for applications with higher system pressure requirements where pipeline space allows. Generally, 90-degree elbows are more frequently used in systems, while 45-degree elbows can be selected at critical points such as fan inlets and outlets to reduce resistance.

PP processing ducts are fabricated by welding sheet materials. Theoretically, the diameter is not limited by the extrusion die, and large-diameter ducts can be manufactured based on customer requirements. The specific dimensions are constrained by the sheet material width and welding processes. In actual engineering projects, large-diameter main ventilation ducts typically range from hundreds of millimeters to several meters in diameter. Ultra-large-diameter ducts can be produced by welding multiple sheet materials together, with flanges and reinforcement bars added to ensure structural strength. The specific maximum diameter must be determined based on sheet material specifications, structural strength requirements, and on-site transportation and installation conditions. Non-standard customization is supported.

Both models exhibit corrosion resistance. The PP fireproof spray tower is lightweight, easy to process and form, features excellent welding and sealing performance, offers high cost-performance, and has a wide acid and alkali resistance range, making it the mainstream choice for acidic and alkaline exhaust gas treatment currently. The fiberglass spray tower has better temperature resistance and structural rigidity, making it suitable for applications with higher exhaust gas temperatures or requirements for large diameters and high mechanical strength. When selecting, factors such as exhaust gas composition, temperature, treatment air volume, on-site installation space, and budget should be comprehensively considered. The manufacturer can provide tailored solutions based on specific conditions. Both materials have their applicable scenarios, with no absolute superiority or inferiority; the key is to match the actual conditions.

PP spray towers are widely used in the waste gas treatment fields of multiple industries such as PCB, electroplating, chemical industry, pharmaceutical, food, electronics, textile, rubber and plastic, automobile, cement, ceramics, etc., especially suitable for acid-base waste gas treatment.

两者都靠填料层和喷淋吸收液净化废气，净化原理相同，区别在材质性能和适用工况。PP 喷淋塔重量轻、加工方便、造价较低，常温稀酸碱工况使用成熟，经济性好。不锈钢喷淋塔耐温更高、整体刚性和承压更强，遇较高进气温度不易软化。它的防火、抗老化和抗机械损伤表现更好，大直径和室外长周期使用更稳妥。选型要结合废气温度、成分、塔径、安装位置和预算综合判断。常温常规工况可选 PP，高温、防火或大塔径工况更适合不锈钢，两者各有适用范围。

V0 PPs housing is acid and alkali resistant, capable of contacting acidic and alkaline mist gases. However, it is not recommended to allow large amounts of water mist or acidic and alkaline mist to directly enter the activated carbon layer in the process: liquid droplets will cause the activated carbon to become damp, block pores, and reduce adsorption capacity. Acids and alkalis may also react with the carbon or adsorbed organic substances. The proper approach is to first pass through spray washing and demisting to remove acidic and alkaline mist, then enter the activated carbon housing for adsorption of residual organic compounds, forming a washing plus adsorption combination process. The carbon housing should be in a dry or low-humidity airflow. This approach leverages the corrosion resistance of the PPs housing while protecting the activated carbon.

Qualified hot melt welding strength and sealing can meet the requirements of corrosion-resistant ducts. Air leakage and cracking are often caused by construction quality and operating conditions, such as improper welding temperature and speed, mismatched welding electrodes and sheet material or flame retardant grade, incomplete penetration or porosity in welds, aging of flange gaskets, excessive pipe support spacing causing stress, and failure to account for thermal expansion and contraction. Control measures include: using V0 welding electrodes of the same material, welding by skilled workers following the process, ensuring full welds and conducting inspections, uniformly tightening flanges, rationally setting supports and thermal compensation, and performing air leakage volume testing after installation.

The process itself does not use water or generate wastewater. The salt produced during the adsorption reaction is fixed within the adsorbent, and there is no wastewater or mist emission during operation, resulting in minimal secondary pollution. However, saturated SDG adsorbents contain acid reaction byproducts and residual chemicals, which are classified as solid waste requiring regulated management. They should be collected, temporarily stored, and disposed of according to their composition and local environmental regulations (typically handled by qualified units), and should not be dumped arbitrarily or mixed with domestic waste. As long as the waste filter media is disposed of properly, the secondary pollution risk of dry adsorption is significantly lower than that of wet processes that generate wastewater.

The length of the flexible joint must meet the requirements for vibration isolation and compensation, but it is not necessarily the longer, the better. If the length is too short, it cannot fully absorb vibration and installation deviations, resulting in poor vibration isolation performance. If it is too long, it tends to collapse under negative pressure and oscillate or bulge under positive pressure, which Conversely increases resistance and wear. Generally, standard lengths are selected based on the fan's diameter, vibration amplitude, and installation spacing, ensuring that the flexible joint maintains a natural, slightly slack state after installation without being stretched or compressed. For tapered flexible joints, it is essential to ensure that the large and small ends match the fan and duct, respectively, with a smooth transition. Specific dimensions can be selected by referring to the product specifications based on the diameters of the two ends and the required axial and transverse compensation amounts. If unsure, provide the fan model and interface dimensions, and the supplier will provide matching components. When installation space is limited, prioritize ensuring the required length for vibration isolation; do not forcefully insert excessively long flexible joints into confined spaces.

When the spigot ends of the insert PVC air damper are inserted into the PVC air duct, PVC special adhesive is applied to the mating surface for bonding and fixing. Before bonding, clean the spigot ends and the pipe ends, insert to the correct position, and mark the depth. After applying the adhesive evenly, insert it fully once, hold it for a moment to allow it to cure, and avoid applying force or rotation during this period. Once the adhesive connection is formed, it cannot be disassembled and is suitable for fixed pipe sections. For disassembly, maintenance, or connections with equipment, flanged valves should be selected, connected with bolts and gaskets, offering convenient assembly and disassembly. The bonding construction environment should be well-ventilated and dry, avoiding work in humid or low-temperature conditions to prevent bonding strength issues. Use an appropriate amount of adhesive and ensure complete coverage on the bonding surface. After bonding, cure it according to the specified time before putting it into use. There should be no gaps or weak bonding at the spigot ends to ensure long-term air leakage prevention.

Common practice involves using the bottom section of the tower as a circulating water tank (integrated), where the tower bottom space stores circulating liquid and receives reflux, featuring compact structure and short piping; large horizontal towers can also have the tank independently placed below or beside the tower body for easier increase in liquid storage capacity and maintenance. Integrated tanks must ensure effective volume meets circulating pump flow rate and retention time, equipped with level, overflow, drain, and chemical addition interfaces. Whether to use integrated or separate design depends on equipment size, on-site layout, and circulating flow rate, which should be confirmed with the manufacturer during ordering.

The long-term operating temperature of flame-retardant PPs panels is similar to that of general polypropylene, making them suitable for handling corrosive gases in ambient to medium-temperature ranges. The specific temperature upper limit depends on the panel thickness, equipment structure, reinforcement method, and fixing form. The equipment should also avoid localized contact with high-temperature heat sources and radiant heat to prevent single-point overheating, which could cause the panels to soften and deform. For high-temperature exhaust gases, a pre-cooling section with a spray cooling stage should be installed before entering the plastic equipment to reduce the gas temperature to within the material's allowable range through gas-liquid contact. If the exhaust gas temperature remains high for extended periods or experiences instantaneous high-temperature impacts, consider selecting high-temperature-resistant stainless steel or fiberglass materials instead of directly using PP panels. When selecting, provide the continuous temperature, peak temperature, and composition of the exhaust gas to determine if pre-cooling or material replacement is necessary.

PPs sheets are inherently non-toxic and odorless, with polypropylene being one of the commonly used food-contact materials; however, flame-retardant grade sheets contain flame-retardant additives, and whether they meet specific food-contact scenario compliance requirements depends on reviewing the corresponding batch test reports and applicable standards. For tanks and containers directly contacting food materials, it is recommended to select pure PP sheets explicitly labeled as food grade; flame-retardant PPs sheets are more suitable for applications such as exhaust emission, ventilation, and peripheral corrosion where they do not directly contact food.

This is a manifestation of closed-loop instability, common causes include electromagnetic interference on control signals, improper tuning of controller adjustment parameters (excessive gain or too small deadband), insufficient actuator torque, valve shaft jamming, and inherent fluctuations in sensor measurements. Check shielding grounding, ensure signal wires are away from power cables, adjust controller proportional-integral parameters and deadband, eliminate mechanical jamming, and verify actuator torque. Frequent small oscillations of the valve disc accelerate actuator wear; closed-loop tuning must be completed before operation.

Variable frequency fan low-speed operation may cause positive pressure difference near the valve disc opening critical point, leading to vibration and slapping of the valve disc, generating noise and affecting airflow. Solutions include selecting check valves with damping or adjustable weights to stabilize the valve disc after opening; optimizing fan control by setting a lower operating frequency limit to avoid the critical zone; for systems with significant operating condition variations and long-term low-speed operation, the check valve can be replaced with an electric sealed valve linked to the fan, which closes with a delay when the fan stops, ensuring smooth and controllable operation.

The welded seams of the PP medicine drum are fused with the base material, ensuring no leakage under normal use. Leakage typically occurs at welding defects, stress concentration points at joints, or cracks in the drum body due to deformation. Before putting a new drum into use, a full water test should be conducted: fill the drum with clean water and let it stand for the specified duration to check for any leakage or sweating at all longitudinal seams, bottom seams, and joints. For square drums, observe for deformation at the reinforcement points. If leakage is detected during operation, drain and clean the drum before repairing the welding; never perform hot work with the drum containing the chemical. Flexible connections or supports should be installed on the inlet and outlet pipelines to prevent the weight of the valves and pipes from being applied to the drum wall joints for extended periods.

Cannot be directly mixed, circular tee for circular pipe, rectangular tee for rectangular pipe, as their interface shapes and flange standards differ. Forcing them to connect will result in cross-section misalignment and air leakage. When converting between circular main pipes and rectangular branch pipes in the same system, use square-to-round adapters or directly create square-round transition sections at one of the tee's interfaces before connecting the corresponding cross-section pipe segments. When ordering, clearly specify the cross-sectional shape, dimensions, and flange standards for each of the three interfaces, indicating which one is square and which one is round to avoid incompatibility upon arrival. Square-round transition tees can be manufactured as a single piece by the supplier, resulting in smoother surfaces and lower resistance compared to on-site assembly. When arranging piping, minimize frequent square-round cross-section conversions. Ensure smooth transitions at conversion points to avoid abrupt expansions or contractions that increase resistance and noise.

Okay, but focus on UV and temperature effects. PP material will age and become brittle when exposed to direct sunlight for a long time. Outdoor-mounted PP ducts are recommended to use weather-resistant sheet material with UV-resistant additives, or to have a UV-protective coating applied to the outer wall, or to install sunshades. Pipe supports must consider wind load, snow load, and thermal expansion and contraction. Fixed supports and sliding supports should be set up reasonably, and thermal expansion compensation should be reserved for long straight pipe sections. In cold regions, the material's low-temperature toughness must be noted to avoid impacts and concentrated loads. Outdoor flanges and bolts should be made of corrosion-resistant materials or have corrosion protection to prevent rust from rain. Installation indoors or in pipe galleries away from direct sunlight ages slower, with more favorable usage conditions. Regardless of indoor or outdoor installation, flammability and corrosion resistance requirements should be configured according to the medium and fire protection regulations.

Do not mix. The welds of fire-resistant air dampers and fire-resistant air ducts must use PPs fire-resistant welding electrodes to ensure that the welds match the fire resistance level of the base material, with no fire-resistant weak points in the entire pipeline. If ordinary PP welding electrodes are used to weld fire-resistant panels, the welds become fire-resistant breaks on the pipeline. During a fire, the welds may melt and crack first, leading to pipeline failure and failing fire inspection. During processing, ensure that the plates, valve plates, welding electrodes, and flanges are all made of the same fire-resistant compatible material. Sealing materials should also be selected as fire-resistant or flame-retardant materials. On-site, store fire-resistant welding electrodes and ordinary welding electrodes separately with clear markings to prevent workers from picking up the wrong ones. After welding, verify the welding electrode packaging and material certification to ensure that the weld areas have the same self-extinguishing properties as the base material.

Cannot be directly connected, as the rectangular and circular cross-section shapes are different, and the flanges are also different, making it impossible to achieve a sealed connection. Rectangular elbows can only be connected to rectangular ducts or square fittings via square flanges, while round elbows are connected to round ducts. When converting between rectangular and circular pipes in the system, a square-to-round transition fitting should be installed between them, and then the elbows and pipe sections corresponding to the respective cross-sections should be connected. Attention should also be paid to smooth transition of the cross-section at the conversion point to avoid sudden expansion or contraction, which increases resistance and noise. When ordering, select elbows and transition components based on the actual cross-section of each section. For nodes with frequent use of both square and round sections, the manufacturer can provide integrated processing of transition-shaped elbows with built-in transitions. Using soft connections or variable-diameter hard connections for square-round cross-sections on-site will cause flow deviation and air leakage, and should not be used.

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