PP fireproofing processed square valve

Product Model	PPs plate-welded rectangular multi-leaf damper
Category	PP Machined Products
Reference Price	Price on request

Hot Customizable for Working Conditions 11 Technical Parameters

Product Overview

The PP Flame-Retardant Square Air Damper is a square fireproof and corrosion-resistant air volume regulating damper with multiple linkage vanes, featuring a rectangular valve body formed by folding and welding PP flame-retardant plates, and integrated with multiple linkage vanes. It upgrades the valve body, vanes, and welding rods to all flame-retardant PP materials based on the PP processing square air damper, offering acid/alkali corrosion resistance and self-extinguishing properties. It is primarily used for laboratory fume hood exhaust, indoor ceiling rectangular ducts, and corrosion-resistant exhaust systems in fire-requiring areas.

Rectangular ducts in laboratory and factory ceilings are numerous and widely distributed, often located in enclosed spaces. If the duct material is flammable, fires can easily spread through the ceiling ducts and are difficult to detect. The PP Flame-Retardant Square Air Damper, when paired with flame-retardant rectangular ducts, forms a complete flame-retardant and corrosion-resistant exhaust network. The multi-vane Interconnection (linking) damper is used for air volume balancing in each fume hood and branch duct. The rectangular multi-vane structure features uniform opening and rigid vanes, making it suitable for applications requiring precise face velocity balancing, such as fume hood exhaust.

Xicheng Environmental can fabricate PP Flame-Retardant Square Air Dampers based on the cross-sectional dimensions of rectangular ducts. The number of vanes is configured according to the valve height. The square flange is matched with PP square pipes, and sealing strips can be added to the edges and ends of the vanes. The handle includes an opening lock, and it can also be equipped with electric or analog actuators to meet variable air volume control for fume hoods.

Working Principle

The adjustment principle of the flame-retardant square air damper is multi-vane Interconnection (linking). Turning the handle or actuator drives the main valve shaft, which, through a crank and connecting rod mechanism, synchronously drives all valve shafts, causing multiple vanes to rotate at the same angle. This changes the multiple airflow gaps of the rectangular cross-section, continuously regulating the air volume. When the vanes are closed, their edges overlap to seal the airflow path, and when open, they align parallel to the airflow. The synchronous movement of multiple narrow vanes ensures uniform cross-sectional opening and consistent air velocity at all points.

The flame-retardant principle is the same as that of circular PP air dampers. The valve body, vanes, welding rods, and sealing components are all flame-retardant or hard-to-burn materials, self-extinguishing and not propagating flames, ensuring the fire integrity of rectangular duct systems in ceilings and indoor spaces. In terms of corrosion resistance, PP vanes do not rust or warp when long-term exposed to laboratory acid/alkali fumes, and the Interconnection (linking) pins are made of corrosion-resistant materials, ensuring long-term synchronous and flexible operation of the multi-vane mechanism in corrosive environments. The outer wall of the rectangular valve body features reinforced ribs to resist negative pressure and prevent large panels from concaving.

Structural Composition

The flame-retardant square air damper consists of a PP rectangular valve body, multiple vanes, valve shafts, crank and connecting rod Interconnection (linking) mechanism, handle or actuator, and square flange. The valve body is formed by folding and welding four PP plates into a square frame, with longitudinal and corner seams continuously welded using PP flame-retardant welding rods, and reinforced ribs welded to the outer wall. The vanes are narrow and long PP plates, each fixed to a valve shaft and arranged parallel along the valve height.

Each valve shaft extends from the same side of the valve body and is equipped with a crank. A vertical connecting rod links them synchronously. The main valve shaft is connected to a handle, opening disc, and locking mechanism, or directly installed with an electric actuator. Sealing strips made of corrosion-resistant and flame-retardant materials can be embedded at the edges and ends of the vanes. When closed, the vanes overlap and fit against the side walls to minimize air leakage. The two ends of the square PP flange correspond to the Flange hole position (flange hole positions) of rectangular ducts. For larger cross-sectional valves, the vanes are reinforced at the edges, and the Interconnection (linking) connecting rods are located within a removable cover for easy maintenance.

Specification Model Table

The table below shows the driving modes and applicable scenarios of the flame-retardant square air damper, with cross-sectional dimensions matching rectangular ducts.

Driving Mode	Control Characteristics	Applicable Scenario
Manual Multi-Vane	Adjustment Lock	Constant Air Volume Branch
Electric On/Off	Remote Operation	Branch Ducts Requiring Isolation
Analog Electric	Continuous Adjustment	Variable Air Volume Fume Hoods

Product Features

The PP Flame-Retardant Square Air Damper is corrosion-resistant, flame-retardant, and features multi-vane uniform airflow distribution, making it a specialized valve for laboratory and ceiling rectangular exhaust systems. Its main features are as follows.

PP plates folded and welded into a rectangular valve body, self-extinguishing and acid/alkali resistant
Full flame-retardant welding rods for valve body and vanes, ensuring safety for ceiling use
Multi-vane Interconnection (linking) with connecting rods for synchronized operation, uniform opening, and precise air volume balancing
Narrow vanes with high rigidity, stable under high air pressure
Sealing strips added to vane edges for minimal leakage when closed
Square flange matched with PP square pipes, available in non-standard dimensions
Compatible with switch-type or analog actuators, suitable for VAV systems

Body Material	PPs Flame Retardant Panels
Welding Rod Material	PPs Flame-Retardant Welding Rod
Processing Technology	Sheet metal welding assembly
Section Shape	rect
Leaflet Valve Form	Multi-leaf linkage
Flame Retardant Properties	Self-extinguishing
Corrosion Resistance Performance	Acid-alkali-resistant salt
Connection method	Square Flange
Drive Options	Manual / Electric / Analog
Sealing Options	Leaflet edge soft seal
Sheet Thickness	Select by cross-section

Application Industries

Flame-retardant rectangular air damper for fume hood exhaust in chemical laboratory
Drop ceiling multi-leaf regulating damper for laboratory exhaust in teaching and research
Corrosion-resistant rectangular exhaust damper for indoor semiconductor and panel factory
PPs square duct valve for ceiling-mounted exhaust in plating workshop
Corrosion-resistant exhaust dry pipe valve for hospital laboratory and pathology
Rectangular corrosion-resistant branch line isolation damper in fire-rated compartment
Analog regulating damper for variable air volume fume hood system

Typical Installation Locations

Flame-retardant square damper is installed on PPs rectangular ducts in indoor and ceiling spaces. One damper is set on each fume hood exhaust port or floor-level horizontal branch/dry pipe in the ventilation system to balance exhaust airflow of each hood and maintain face velocity. A branch line isolation damper is installed before the floor or fire-rated compartment connects to the vertical shaft. When the damper is integrated into the ceiling or duct shaft, maintenance openings must be reserved on the side of the operating handle and linkage mechanism. For electric valves, power supply and control lines must also be reserved.

In constant air volume systems, manual multi-leaf dampers are adjusted and locked once. In variable air volume fume hood systems, analog electric flame-retardant square dampers are installed on the fume hood top or branch pipes, driven by the ventilation system face velocity controller to continuously regulate the damper vane. Rectangular ducts passing through fire-rated compartments require separate fire dampers and seals according to fire protection design. Flame-retardant square dampers cannot replace fire protection dampers. During installation, square flanges must be centered, gaskets sealed, and the valve shaft installed horizontally to ensure even vane weight distribution.

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.

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.

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.

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.

The two products serve different functions and are used in series. The flame-retardant square damper is responsible for daily airflow regulation and is made of self-extinguishing material. The fire-rated damper is installed at air duct penetrations through fire compartments, floors, and machine rooms, and is controlled to close by temperature-sensitive melting or electrical signals, featuring fire resistance and smoke prevention functions. In laboratory exhaust systems, flame-retardant regulating dampers are installed at the outlets of fume hoods, and fire-rated dampers are installed at fire compartment penetrations. Flanges are used for reliable connections between plastic ducts and fire dampers, with fireproof sealing applied. The locations of penetrations and the number of dampers are determined according to building fire protection design, and the installation is included in fire inspection after construction.

Provide rectangular valve body cross-sectional dimensions (width x height), square flange dimensions and hole positions, number of valve leaves or valve height, valve shaft direction, actuation method (manual, on/off electric, or analog electric with signal type), actuator torque and protection requirements, material flammability rating, seal strip requirements, air duct pressure and medium composition. For VAV systems, provide control method and valve position feedback requirements. Attach fume hood exhaust drawings and ceiling access panel location to ensure correct valve operation orientation.

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