FAQ

PP ducts primarily use two connection methods: spigot connection and flange connection. Spigot connection involves inserting one end of the duct into the socket of another duct or fitting, sealed with sealant or a gasket, offering easy installation and suitability for medium and small diameters. Flange connection involves welding flanges at both ends of the duct, connecting the two flanges with bolts and adding a sealant pad, providing excellent sealing performance and secure connection, ideal for large diameters and applications requiring frequent disassembly. The specific connection method should be selected based on diameter, pressure, and maintenance needs. Before installation, check if the pipe ends are flat and, if necessary, use sandpaper to smooth them for easy insertion.

The specifications of the PP elbow should match the specifications of the paired PP ducting to ensure dimensional compatibility during spigot-and-socket connection. When selecting, first determine the duct diameter and cross-sectional shape: round ducts require round elbows, and square ducts require square elbows. Xicheng Environmental offers a wide variety of PP elbows with comprehensive specifications, covering standard small diameters to large diameters, all directly compatible with the same-specification PP ducting. For non-standard size ducts, custom-made elbows can be provided to ensure reliable connection and sealing.

The welded seams of PP processed ducts use PP welding technology, ensuring robust welding and excellent sealing performance. PP material exhibits excellent hot welding properties, with weld strength reaching a high proportion of the base material strength. Under normal operating conditions, the welds will not crack or leak. Welding quality depends on the welding process and the technical proficiency of the operators. Xicheng Environmental possesses a professional PP welding processing team and a rigorous quality inspection process to guarantee that every weld is firmly sealed. Large-diameter ducts are further reinforced with flange stiffeners and reinforcement ribs to enhance structural strength and ensure long-term stable operation.

The selection primarily requires the following parameters: First, the nature of the exhaust gas, including pollutant composition, concentration, and acid-base type; second, the treatment air volume, measured in cubic meters per hour; third, the exhaust gas temperature and humidity; fourth, the on-site installation space, including height and footprint limitations; fifth, the required purification efficiency and applicable emission standards; sixth, material preferences. Providing these parameters allows for matching the tower diameter, tower type, and circulating water pump. Standard tower diameters cover φ800 to φ3000, with non-standard designs available for special conditions. If flammable and explosive exhaust gas is involved, the gas composition and explosion-proof requirements must also be specified.

The activated carbon adsorption tower can adsorb and recover waste gases from organic solvents such as benzene, alcohols, ketones, esters, and gasoline, and is suitable for organic waste gas treatment and VOCs control. Xicheng Environmental Protection adopts a drawer-type design, making loading and replacing carbon more convenient.

This is determined by the inherent properties of the metal material itself. The stainless steel exhibits significantly higher heat resistance temperature compared to plastics such as PP. When exposed to higher inlet temperatures, it does not soften, collapse, or deform, maintaining stable structural dimensions. The tower body, welded as an integral unit, possesses strong rigidity and can retain its shape and seal under thermal expansion and contraction as well as long-term high-temperature airflow. Its fire resistance performance also surpasses that of plastic towers, making it suitable for placement near production line heat sources. The specific maximum inlet temperature it can withstand depends on material grade, plate thickness, insulation, and the material of the packing demister. This requires technical personnel to calculate based on actual flue gas temperature, while also considering the temperature resistance of the absorption liquid and internal non-metallic components during selection.

Need to provide the following parameters: airflow rate, VOC components and concentration, waste gas temperature and humidity, whether it contains acid-base mist and dust, required purification efficiency and emission standards, installation location (indoor or outdoor) and available space, flame retardancy level requirements for the housing and ductwork, and the orientation and size of the inlet and outlet ports. The airflow rate determines the cross-sectional area of the housing and the number of drawers, the components determine the type and loading amount of activated carbon, and indoor installation determines the V0 flame retardant configuration and external dimensions. After providing the parameters, the manufacturer designs based on the residence time and carbon layer thickness, and provides matching V0 flame retardant ductwork, dampers, and monitoring instruments.

Dry adsorbents are suitable for treating acid gases at room temperature with relatively low humidity; excessively high gas temperatures may affect adsorption performance and the lifespan of the housing material, while high humidity and liquid presence can cause the adsorbent to dampen, cake, and increase resistance. Before entering the adsorption chamber, high-temperature gas should be cooled, and high-humidity or foggy gas should be dehumidified and de-fogged. Although the equipment has no anti-freeze requirements (dry operation is not afraid of freezing in winter), condensation and rain should be avoided, and rain protection should be ensured for outdoor installation. The specific temperature and humidity applicability range should be confirmed with the manufacturer and designed according to the exhaust gas conditions.

Through transparent soft connections, you can observe whether there is obvious water mist entrainment, liquid droplet flow, dust accumulation, and liquid accumulation inside the pipe, thereby determining whether the upstream demister is carrying water, whether the pipeline is blocked, and whether the fan inlet conditions are normal. Transparent soft connections are installed at the outlet of the spray tower, after the demister, and at the fan inlet. During inspections, no holes need to be drilled or the machine needs to be shut down to monitor the internal status, which helps to promptly identify water carryover, dust accumulation, and liquid accumulation issues. Transparent soft connections expose the operational status visually, which is helpful for judging demister effectiveness and pipeline flushing timing. However, transparent soft connections can only serve as an intuitive operational observation window and cannot replace professional detection instruments such as differential pressure and flow meters. Accurate judgment still relies on instrument data. When the transparent material yellows due to aging, the observation effect decreases. It should be cleaned or replaced promptly to maintain a clear view.

Normal regulating valves have a designed gap between the valve disc and the valve body, resulting in air leakage even when fully closed. This is a normal characteristic of regulating valves and should not be measured by the same standards as sealed valves. If the process requires tight closure, isolation for maintenance, or prevention of gas backflow, a sealed valve with a soft seal on the valve disc edge should be selected. For existing valves that do not close tightly, check in sequence: whether the seal on the valve disc edge has aged or detached, whether the valve shaft is loose causing the valve disc to be misaligned, whether there are foreign objects stuck inside the valve body, and whether the valve disc is deformed. After cleaning or replacing the seals, re-adjust the valve disc stroke and limit. For manual valves, ensure the locking mechanism is effective; for electric valves, verify the actuator stroke and the closed position signal. If the gas tightness requirement is still not met after treatment, replace it with a sealed valve. Do not force a normal regulating valve closed by increasing operating force.

Indoor exhaust gas treatment equipment should use PPs flame-retardant panels and be equipped with flame-retardant welding electrodes, with flame-retardant performance of the materials meeting building fire protection requirements. Equipment layout must comply with fire separation distances, fire lanes, and equipment room specifications. The electrical components of the Matching Fans and pumps must meet protection requirements. Fire dampers and seals must be installed at the tower and duct penetrations through fire compartments according to fire design. While the wet operation of spray towers has a low fire risk, the PPs materials and chemicals used during maintenance still require management. The equipment room should be equipped with drainage, ventilation, and flushing facilities. Flame retardancy of the equipment is only one aspect of fire safety. The tower area must also be equipped with fire dampers, compartment seals, and fire extinguishing facilities in accordance with building fire protection requirements. The overall fire protection design and construction must be completed by professional units.

Yes. PPs sheets can be cut using woodworking circular saws, handheld cutters, and engraving machines. On-site construction involves cutting to measured dimensions, followed by splicing and welding using handheld hot-air welding guns. The processing method is largely consistent with workshop production. When cutting, use fine-toothed blades and control the feed speed to minimize edge chipping and burrs. The cut edges should be leveled with a scraper before welding. The on-site processing environment should be kept dry and well-ventilated. Clean the sheet surface of oil, dust, and moisture before cutting and welding to ensure weld fusion quality. During winter construction, the ambient temperature should not be too low, as this can reduce the sheet's toughness, making it prone to cracking during bending and curling. It is advisable to warm the sheets indoors first. Welds made on-site also require visual inspection, with load-bearing and sealing areas subjected to welding inspections according to workshop standards.

When the width of a single plate is insufficient for large-diameter tower bodies and wide-section ducts, multiple plates need to be spliced and welded before rolling; proper splicing adopts double-sided welding or groove welding, ensuring thorough fusion of the electrode with the base material, followed by leak detection after welding; qualified splices exhibit equal strength to the base material and are leak-proof, with key equipment also capable of adding reinforcing strips outside the welds; splicing quality depends on groove preparation, welding temperature, and welder operation, making it effective to select a manufacturer with processing experience to avoid potential leakage hazards.

The valve position feedback reflects the mechanical angle of the valve disk, not the linear airflow. The valve opening and airflow are influenced by network pressure, fan operating conditions, and other branches, exhibiting a nonlinear relationship, with airflow changes particularly sensitive in the small opening area. For precise airflow display or control, install airflow sensors on the pipeline or select venturi valves with airflow measurement, allowing the controller to close the loop based on actual airflow measurements rather than just valve position estimation. During commissioning, measure the airflow at each valve position and establish a relationship curve to improve control accuracy.

Must meet both corrosion resistance and flame retardancy. Seals are critical components for check valves to achieve sealing, directly contacting corrosive gases; if flame retardancy is prioritized over corrosion resistance, seals will swell, harden, and fail due to acids, alkalis, or solvents; conversely, if only corrosion resistance is considered without flame retardancy, they become combustible parts in the flame retardant system. When ordering, provide exhaust gas composition, concentration, and temperature, and the manufacturer will select an elastic seal material that meets both media compatibility and flame retardancy requirements, while material certificates should be obtained for spare part replacement using the same material specifications.

The cylindrical drum features uniform stress distribution, material savings, smooth inner wall for easy cleaning, and no stirring dead zones. It offers the lightest structure and most material-efficient design for the same volume, making it suitable for spaces that allow for independent placement. The square drum has a compact planar layout, enabling multiple drums to be placed side by side with minimal floor space. Its top platform facilitates the installation of mixers, dosing pumps, and pipelines, making it ideal for tight spaces in dosing rooms with multiple drums arranged in parallel. However, the square drum requires more reinforcing ribs and thicker wall panels to withstand liquid side pressure. When selecting, consider the dosing room layout, single-drum capacity, mixing requirements, and equipment installation needs. Large-capacity storage drums are preferably cylindrical, while complete dosing systems often use square drums in multi-drum configurations. Regardless of the shape, ensure the drum strength, foundation load-bearing capacity, and corrosion resistance meet requirements, while also leaving space for maintenance, dosing, and liquid level observation.

Required, especially for large diameters and horizontal branches. The main function of the branch connection weld in a tee is to ensure sealing and diversion. It should not bear the cantilever weight of the branch or operational vibration for long periods. Horizontal branches should be equipped with support brackets near the tee, while vertical pipes should have fixed brackets to transfer the weight and thermal expansion stress of the branch to the brackets, preventing stress concentration at the tee weld that could lead to cracking. When heavy components such as valves and actuators are installed on branches, independent supports must be provided on both sides of the valves to prevent the weight from pressing on the tee and pipes. The type and spacing of support brackets should be determined based on the branch diameter, wall thickness, and medium, with denser arrangements required for large-diameter plastic pipes. The installation sequence should prioritize fixing brackets first, followed by welding and connection, to avoid misalignment and additional stress caused by welding in a suspended state. Regular inspections should be conducted after operation to check for deformation in the tee welds and brackets.

Wall thickness is determined comprehensively by duct diameter, internal/external pressure difference, installation span, and whether reinforcement is required. Larger diameter, higher negative pressure, and wider support spacing require greater wall thickness, with reinforcement rings used if necessary. While industry typically uses empirical tables to select wall thickness based on diameter and pressure, critical projects must rely on design calculations. Avoid using excessively thin plates on large-diameter, high-negative-pressure sections to prevent collapse, vibration, and noise; however, full-thickness reinforcement is unnecessary and wasteful, with segmented configuration being the most rational.

Conventional flame-retardant PP boards are made by adding flame-retardant components to polypropylene, with the main material still being polypropylene. Their corrosion resistance to common acids, alkalis, and salt gases is comparable to that of standard PP, meeting conventional corrosion-resistant ventilation requirements. However, the added components may affect the material's tolerance to certain strong oxidizing media or special solvents. When encountering chromic acid mist, concentrated nitric acid, strong oxidizing agents, or special organic substances, the medium composition, concentration, and temperature should be actively specified. Material selection should be made by the manufacturer or based on corrosion resistance data, and corrosion compatibility tests may be required when necessary. It should not be assumed that flame-retardant materials are inherently resistant to all media. For conventional acid-alkali ventilation, they can be used with confidence. For complex compositions or strong oxidizing conditions, the corrosion resistance table should be checked or a more corrosion-resistant material should be used to ensure the valve remains corrosion-free over the long term.