FAQ

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.