FAQ

Under the same cross-sectional area and airflow rate, circular pipes have a smaller wet perimeter and more uniform airflow distribution, typically exhibiting lower frictional resistance compared to rectangular pipes. Rectangular pipes, especially those with a wide flat shape, have low-velocity zones at their four corners, resulting in slightly higher resistance, which becomes more pronounced with a larger length-to-width ratio. However, as long as the internal flow velocity is properly controlled, the inner wall welds remain smooth, and the number of elbows and abrupt cross-sectional changes is minimized, the frictional resistance of square pipes remains fully within acceptable limits. The value of square pipes lies in their strong adaptability to space, allowing them to fit along beam bottoms and ceiling layouts. When selecting, it is essential to comprehensively compare layout requirements, frictional resistance, and fan energy consumption, rather than focusing solely on the coefficient of friction. For long-distance, high-negative-pressure main pipes, circular pipes should be prioritized, while square pipes are suitable for indoor wide flat sections and beam-mounted segments. When necessary, the resistance can be compensated by appropriately enlarging the rectangular cross-section and reducing the flow velocity, ensuring both circular and square pipe energy consumption remains at reasonable levels.

The valve leaf and valve body are made of PP plastic, which is rust-resistant. However, if the linkage crank, pins, and bushings are made of ordinary metal parts, they may rust, expand, and jam under the long-term effect of acidic or alkaline gases. It should be required that these moving parts be made of stainless steel, engineering plastics, or coated with anti-corrosion materials. The bushings should be selected from self-lubricating, corrosion-resistant materials to reduce exposed metal. If asynchronous operation or difficult rotation of the valve leaf is detected during operation, the machine should be shut down to check whether the pins are rusted or crystallized and whether the connecting rod is deformed. Clean, lubricate, or replace them in a timely manner. The connection between the actuator and the valve shaft also requires anti-corrosion treatment, and the connecting parts should preferably be made of stainless steel. Daily inspections should be combined with ceiling inspection openings to focus on listening for any abnormal noises and checking whether the valve position is accurate. If jamming is detected, it should be addressed early to avoid the actuator being overburdened for a long time.

Switched electric valves paired with conventional diaphragms still exhibit air leakage when fully closed, suitable for general isolation but require hermetically sealed electric valves with diaphragm edges equipped with soft sealing strips and actuators with sufficient closing torque for airtight requirements. When air leakage increases, inspect if the sealing strip is aging, if the diaphragm is fully closed (check limit and actuator travel), if there are foreign objects in the valve body, and if the actuator connection to the valve shaft is loose or slipping. For zero-leakage isolation applications, select electric sealed valves instead of conventional electric regulating valves.

If the flow in the gradually expanding section detaches, forming a low-speed vortex zone, dust tends to deposit at the variable diameter. For horizontal eccentric reducers, if the direction is selected incorrectly, liquid and dust sumps will form at the bottom. When handling dusty or liquid-containing gases, horizontal pipes should preferably use eccentric reducers with flat bottom surfaces, maintaining a continuous slope at the bottom, and installing drain or cleaning ports at the low points for regular cleaning. Controlling the reducer angle and maintaining sufficient conveying velocity inside the pipe can also reduce dust and droplet deposition. Plastic inner walls are smooth with lower adhesion than metal, but during long-term operation, inspections should still be conducted during maintenance to check for deposits at the reducer sections. If liquid and dust accumulation is detected, it should be cleared promptly, and the eccentric direction and velocity should be reviewed to ensure they are appropriate. Eliminate deposition dead zones in the layout to prevent deposits from corroding the material or fostering microbial growth.

Before welding, first drain all liquids from the equipment and thoroughly dry the leakage area. Clean the weld surface of contaminants, crystallization, and oxidation layers using a scraper or sandpaper to expose the fresh base material. Then, create a shallow V-shaped groove along the leakage seam to facilitate the welding rod penetration. Next, use welding rods of the same material and color to reheat and weld. First, weld a fine line along the seam to seal the leak points, then add width and height to the surface with a second layer as reinforcement to ensure proper fusion. After welding, perform a water or air pressure test to check for leaks, focusing on the original leak points and new welds. Confirm no leaks before putting it back into use. Welding in a wet condition can cause porosity and incomplete fusion; ensure the surface is completely dry. If the same area leaks repeatedly, check for structural stress or plate thinning, and apply reinforcing plates if necessary.

Switched electric valves only have two stable positions: fully open and fully closed, and cannot be left in a mid-position for extended periods. Forcing repeated adjustments using the jogging method can cause frequent motor operation, inaccurate positioning, severe overheating, and potential motor burnout or limit switch damage. They are not suitable for continuous regulation. For applications requiring automatic control of airflow size based on sensor signals, analog control valves should be selected. The actuator can stably stop at any angle according to the control signal and feed back the actual valve position to the system, achieving closed-loop regulation. Switch valves address on/off and isolation, while regulating valves address airflow size. Their structures and control methods differ, and they should not be mixed. If the system requires both continuous regulation and tight isolation, an analog control valve can be cascaded with an electric sealed valve to separately handle regulation and isolation functions.

The ring itself is merely a connecting piece and does not bear the weight of the pipeline. Support brackets should be independently installed based on pipeline weight, diameter, and span requirements, ensuring welds are not subjected to long-term load. The location of the ring joint should be near the support bracket arrangement to avoid placing the joint exactly at the position of maximum deflection between two brackets, preventing long-term bending stress on the joint. For vertical pipelines, fixed brackets should be installed below the ring joint to support the weight of the upper pipeline section. The spacing of horizontal pipeline brackets is determined based on pipe diameter and wall thickness, with appropriate densification for larger diameters. Proper bracket arrangement can reduce bending moments and vibrations at the joint, extending the service life of welds. During installation, brackets should be fixed first, followed by welding the joint, to prevent misalignment and additional stress caused by welding under suspended pipeline conditions.

Yellowing and blackening of the plate indicate over-heat carbonization, suggesting the welding torch temperature setting is too high, or the welding tip remains stationary at the same position for too long, or the welding speed is too slow. Overheating of polypropylene leads to decomposition and carbonization. The carbonized areas become brittle, strength decreases, and the weld develops porosity, which cannot be salvaged through re-welding. It is necessary to completely remove the carbonized layer and re-weld. The temperature setting should be reduced, and the welding tip and electrode should move uniformly along the weld to ensure even heat input, avoiding prolonged heating at localized points. For thick plate welding, multi-layer multi-pass welding is recommended, controlling inter-pass temperature rather than single high-temperature, long-duration baking. Preheating can be applied when the ambient temperature is low or the plate is thick, but the preheating temperature must also be uniform, avoiding localized baking.

The valve body itself is generally not directional, but the valve disc opening direction should follow the airflow direction or avoid the dusty side to reduce dust accumulation and airflow impact on the valve disc; the handle and scale should face the operation passage for easy observation of the opening degree and rotation operation. The valve shaft should be installed horizontally to ensure uniform distribution of the valve disc's self-weight, avoiding uneven weight distribution that could cause the opening degree to change automatically. During installation, the two ends of the valve body should be coaxially aligned with the air ducts, and avoid forcing alignment to prevent deformation of the valve body under stress. The flange connection should be tightened diagonally and evenly, and during welding of the spigot connection, avoid scorching the valve disc and sealing components. Sufficient space should be left around the valve position for operation and maintenance, with no pipes or supports obstructing the handle's rotation range. After installation, manually open and close the valve several times to confirm smooth rotation and accurate opening indication before proceeding with commissioning.

The number of observation windows is determined based on the height of the tower and internal layers, with the principle of ensuring that each critical process section is within the visible range. A common practice is to set one observation window per layer for spray nozzles, to observe misting and liquid film formation. Observation points are installed at the middle and upper/lower sections of the packing section to check for blockages, bypassing, and liquid levels. One observation window is typically installed in the demisting section to monitor water carryover at the outlet. Observation windows may also be required for the sump or recirculation liquid section to observe liquid level and water quality. Small and medium-sized towers usually require several observation windows to meet inspection needs, while tall towers should have them appropriately increased based on layers. Excessive observation windows can increase the number of openings in the cylinder and potential air leakage points, weakening the cylinder's strength. They should be reasonably arranged to avoid redundancy while meeting observation requirements. When determining the location, it's also necessary to consider inspection pathways and the standing height of operators to ensure the observation windows are truly convenient to use.

Failure to open is often due to incorrect installation direction, valve shaft jamming, valve disc being stuck by foreign objects, or crystallization at the shaft seat; failure to close tightly is often due to foreign matter between the valve disc and seat, damaged seal ring, valve shaft not in horizontal position, valve disc deformation, or rusted rotating shaft; during troubleshooting, shut down and open the maintenance port, clean the jamming objects and crystallization, check the valve shaft horizontal degree and rotation flexibility, replace aging seal ring and damaged shaft sleeve. Corrosion-resistant check valves should regularly inspect the valve disc status during fan maintenance, clean the dust and crystallization before putting back into service.

The closing of the gate disk and seal in large-diameter closed valves requires significant force, making direct operation with a straight handle very labor-intensive. Typically, a handwheel screw or worm gear with eccentric pressing mechanism is used to achieve speed reduction and force multiplication, allowing a single person to complete opening, closing, and pressing. If the large-diameter valve also requires remote control or frequent operation, an electric closed valve should be selected, where the actuator provides the closing torque and achieves interlocking. During selection, provide the size, air pressure, and installation location, and the manufacturer will configure the corresponding specifications of the pressing mechanism and operation method. When operating, apply force slowly in the specified direction and lock in place. Avoid using a force pipe to violently turn the handle, as this may damage the locking mechanism, bend the valve shaft, or damage the seal. Regularly inspect the wear and lubrication status of the handle, screw, and locking components. Address any sticking issues promptly to ensure reliable closing in emergency situations.

The plastic Raschig rings themselves are acid and alkali resistant and insoluble. Under normal operating conditions, there is no fixed replacement period. Whether to replace them depends primarily on the actual condition of the packing. When the packing is heavily broken, deformed, crystallized, severely blocked by sludge, and the effective specific surface area decreases, leading to a continuous increase in tower resistance and a reduction in purification efficiency, and cannot be restored after rinsing, it should be replaced in batches or as a whole layer. Strengthening the filtration of the circulating liquid, controlling dust and crystalline materials entering the tower, and regularly rinsing the packing and water tank can significantly extend the service life of the packing. Daily records of changes in tower resistance, circulating liquid turbidity, and outlet concentration should be kept as a basis for determining cleaning and replacement. During replacement, remove the old packing, inspect the support grating and spray nozzles, and then refill according to specifications. For towers with varying degrees of aging and blockage, the most severely affected sections can be replaced first to gradually restore overall performance.

PP is acid and alkali resistant, water-absorbent, and rust-proof, offering a longer service life in indoor corrosive environments. Aging primarily results from ultraviolet exposure and prolonged high temperatures. In indoor workshops without direct sunlight and normal temperatures, aging occurs slowly, allowing the platform to be used for extended periods. When installed outdoors or near heat sources, the material gradually becomes brittle and its strength decreases. In such cases, UV-resistant materials should be selected, shading treatment should be applied, and the platform should be kept away from high temperatures. During daily use, platforms with surface cracking, broken reinforcement bars, worn-out anti-slip protrusions, or significant deformation should be replaced promptly. Standardized panels make individual disassembly and replacement convenient without requiring the removal of entire sections. Establish an inspection system, focusing on checking panels in heavy-load areas, corners, and near support structures. Detecting aging signs early and replacing affected panels can prevent damage during foot traffic, ensuring safety.

When the valve disc operates at a small opening, high-speed airflow passing through the valve disc edge generates strong pulsation and eddy currents. If the valve disc stiffness is insufficient or the valve shaft clearance is excessive, it may induce valve disc vibration and noise, leading to fatigue damage of the shaft seat and valve disc over time. The solution involves using reinforced or double-layer structures for the valve disc to enhance stiffness, thickening the valve shaft, employing bearings to reduce clearance, and avoiding prolonged operation of the valve at very small openings. System regulation should preferably use fan frequency control to replace valve throttling, fundamentally reducing the pressure differential across the valve and vibration. During selection, provide the air pressure and regulation range, allowing the manufacturer to strengthen the rotating components and valve disc accordingly. For valves already experiencing vibration, appropriate measures include reducing the pressure differential across the valve, increasing the opening, or replacing the valve disc with higher stiffness and a bearing-supported shaft seat.

Cannot directly connect, as the rectangular flange and circular pipe opening have different shapes, making it impossible to achieve a sealed fit. Rectangular square air valves can only be connected to rectangular ducts and rectangular pipe fittings via square flanges. When connecting to round pipes, add square-to-round transition joints at one or both ends of the valve, then connect to round pipes or circular equipment. When ordering, specify whether the valve ends are square or round. If a round-to-square configuration is required, custom-made square-to-round transition air valves can be ordered. One-piece molding results in smoother surfaces and less air leakage compared to on-site assembly. On-site use of diameter reducers or rigid/soft connections for square-to-round cross-sections can cause flow deviation, air leakage, and additional resistance, which is not recommended. When arranging, clearly define the sequence of square-to-round conversions, soft connections, and air valves, and verify the flange standards of each section to ensure a successful one-time connection on-site.

First, confirm whether the actuator has reached the fully closed position and whether the limit is correct, then check if all vanes are synchronized, if the edge sealing strips have fallen off or aged, and if there are any Miscellaneous items stuck between the vanes or between the vanes and the side walls. When the multi-vane valve is closed, the edges of the vanes should interlock with each other and make contact with the side wall. Adjusting the length of the linkages can correct the closing angle of the vanes. For applications requiring high gas tightness, directly order the sealed electric multi-vane valve equipped with circumferential sealing strips and side sealing. Ordinary electric square valves are primarily used for on-off and regulation, and do not guarantee zero leakage.

Airflow reduction is typically caused by increased system resistance, with the most common cause being the blockage of the packing layer by salt crystallization, dust, and sludge. The next most common causes are fouling and blockage of demisters, nozzle blockage leading to increased liquid carryover resistance in the tower, and liquid accumulation in ducts. Check the pressure drop and blockage locations section by section: clean or replace the packing, clean the demisters, clear the nozzles, drain the sediment from the sump, and enhance pre-treatment dust removal and circulating liquid filtration. Fan belt slip and impeller scaling can also reduce airflow, requiring simultaneous inspection of the fan. Establishing a regular flushing and pressure drop monitoring system can detect blockages before a significant drop in airflow occurs.

The square-to-round transition is constructed by welding multiple twisted panels together. The longitudinal seams and the transition ring seams between the square ends and round ends are the primary areas prone to air leakage, with common causes including incomplete welding at seams, lack of penetration, flange deformation, or improper gasket sealing. During processing, ensure accurate unfolding and cutting, continuous full-welding of panel seams after alignment, reinforced flat surfaces on square flanges, and uniform roundness on round ends. During installation, ensure gaskets on both flanges are intact and bolts are tightened diagonally evenly. After installing the negative pressure system, conduct air leakage checks, focusing on twisted panel seams and the square-to-round transition areas. Mark any detected leaks, then perform backwelding or replace gaskets after pressure relief. With accurate cutting, full welding, and flat flanges, the square-to-round transition can achieve sealing performance comparable to standard ductwork.

Yes. Multi-sphere media features large voids and moderate liquid retention, providing ample surface area for microbial attachment both internally and externally. The voids ensure smooth gas passage, making it a common choice for biological carriers in bio-washing and bio-filter odor removal equipment. When used in biofilm processes, select media with surfaces conducive to attachment, material resistant to aging and biological corrosion, while ensuring uniform nutrient supply, temperature, and spray distribution to achieve consistent biofilm coverage across the bed. During operation, control biofilm thickness by adjusting spray volume and performing regular rinsing to prevent blockage and anaerobic conditions caused by excessive film buildup. The packing height of the media and gas-liquid residence time must meet odor load and compliance requirements, with pre-treatment needed if inlet concentrations are excessively high. The decision to use multi-sphere media should be based on the residence time, volumetric loading, and attachment method of the biological process.