PP Fire-Resistant Analog Air Valve

Product Model	PPs Analog Control Damper
Category	PP Machined Products
Reference Price	Price on request

Hot Customizable for Working Conditions 10 Technical Parameters

Product Overview

The PP Flame-Retardant Analog Damper is a PP flame-retardant damper equipped with an analog调节type electric actuator. Unlike switch-type electric dampers that can only open or close fully, it can receive continuous electrical signals from the control system, stabilizing the vane at any angle between fully closed and fully open, and feeding back the current position to the control system. This enables continuous, precise, and automatic regulation of airflow, making it the end-execution component for variable air volume (VAV) ventilation and intelligent exhaust systems.

In laboratory VAV fume hood systems, changes in the sash opening alter the exhaust area, requiring real-time airflow adjustment to maintain safe face velocity. In workshop negative pressure control, fan frequency modulation, and multi-circuit airflow balancing, dampers also need to operate continuously based on sensor signals. Analog dampers receive standard signals (commonly 0-10V voltage or 4-20mA current signals) from the controller. The servo circuit inside the actuator compares the target position with the actual position and drives the motor in forward or reverse direction, allowing the vane to precisely track the target opening.

The PP flame-retardant analog dampers supplied by Xicheng Environmental Protection are available in formed circular and plate-welded rectangular multi-leaf designs. The PP valve body is self-extinguishing and acid/alkali-resistant. The actuator is equipped with position feedback and a manual mechanism, and can interface with face velocity controllers, differential pressure sensors, PLCs, and building automation systems. It is suitable for corrosion-resistant exhaust systems in laboratories, chemical plants, and semiconductor facilities requiring precise ventilation control.

Working Principle

The core of an analog damper is position closed-loop control. The controller calculates the required damper opening based on the deviation between the setpoint (face velocity, differential pressure, or airflow) and the measured value, using a control algorithm, and outputs the corresponding analog signal. The actuator converts the signal into a target angle while internally measuring the actual angle of the output shaft using a potentiometer or encoder. When the two angles differ, the motor drives the vane through a reducer until the actual angle matches the target angle, achieving precise vane tracking.

Changes in vane angle alter the pipeline flow area and local resistance, thereby adjusting the branch airflow. In VAV fume hood systems, when the sash is opened wider, the controller commands the vane to open wider and increase exhaust airflow. When the sash is closed, the vane closes to reduce airflow, maintaining the face velocity at the sash opening within a safe range. This ensures pollutants are contained while avoiding unnecessary airflow waste. The PP valve body is corrosion-resistant and flame-retardant, with corrosion-resistant shaft seals and bushings ensuring smooth, non-sticking, and airtight operation of the vane in corrosive gases during long-term small-angle reciprocating adjustment.

Structural Components

Analog dampers consist of a PP valve body, vane (or multi-leaf vanes), shaft, shaft seat seal, analog regulating actuator, mounting bracket, and interfaces. The valve body is a formed cylinder or plate-welded rectangular frame, with the vane fixed to the shaft. Rectangular dampers use a multi-leaf联动 structure. The shaft's extending end connects to the analog actuator, which is mounted on the outside of the valve body via a bracket.

除了电机和减速机构外，模拟量执行器内部还包含位置检测元件、伺服控制电路板和反馈电路，具有控制信号输入和阀位信号输出端子，常见信号为 0-10V 或 4-20mA，部分型号支持总线通信。执行器带手动释放机构和开度刻度，调试和断电时可手动操作。阀体两端采用承插或法兰连接，阀瓣边缘可加装密封条以提高小开度时的调节线性度和关闭气密性。

Specification Model Table

The following table compares the functions of analog dampers and switch-type electric dampers. Signal standards must be specified during selection.

Item	Analog Regulation Type	Switch Type
Position	Any opening degree	Full open/full close
Input Signal	0-10V / 4-20mA	Switching signal
Position Feedback	Continuous feedback	End-of-travel contacts
Application	VAV negative pressure control	Start/stop interlock isolation

Product Features

The PP flame-retardant analog damper can continuously and precisely adjust airflow with closed-loop feedback, making it the core valve for VAV and intelligent corrosion-resistant exhaust systems. Key features include:

PP flame-retardant valve body, self-extinguishing and acid/alkali-resistant
Receives standard analog signals, enabling continuous vane adjustment at any opening degree
Internal position closed-loop for precise positioning and position feedback
Automatically maintains face velocity and negative pressure stability with sensors
Available in circular and rectangular multi-leaf designs, compatible with VAV
Actuator with manual mechanism for operation during commissioning or power outages
Reduces unnecessary exhaust, lowering fan and air conditioning energy consumption

Body Material	Flame Retardant Polypropylene (PPs)
Body Type	Formed Round / Plate-welded Rectangular
Drive Type	Analog Electric Actuator
Control Signal	0-10V / 4-20mA
Valve Position Feedback	Analog continuous feedback
Adjustment Characteristics	Continuous regulation at any opening
Flame Retardancy	Self-extinguishing
Corrosion resistance performance	Acid and Alkali Salt Resistant
Manual operation	Actuator with manual mechanism
System Integration	Controllers / PLCs / Building Automation

Application Industries

Lab VAV fume hood face velocity control
Chemical lab exhaust main duct pressure differential VFD linkage adjustment
Biosafety lab room negative pressure gradient control
Semiconductor plant exhaust branch duct airflow automatic balancing
Chemical workshop localized exhaust adjustment based on pollutant concentration
VFD system terminal analog valve actuation
Corrosion-resistant exhaust volume regulating valve for BMS integration

Typical Process Locations

Analog dampers are installed on PP corrosion-resistant ducts requiring continuous airflow control, most commonly at the exhaust ports of VAV fume hoods or on top of the cabinets. The valve actuator connects to the fume hood face velocity controller, with cabinet door displacement or face velocity sensor signals input to the controller. The controller outputs an analog signal to drive the dampers. On room exhaust branch ducts, analog valves work with room pressure differential or airflow sensors and VFD fans to form a closed loop, maintaining stable exhaust volume and negative pressure.

When integrating with BMS systems, ensure unified signal standards and ranges. Control signals and valve position feedback should use shielded cables with proper grounding to avoid interference from power cables causing vane vibration. During commissioning, first calibrate the vane's full open/close positions against signals, then perform closed-loop tuning with the controller. Verify the vane's followability and stability to signals, confirm face velocity remains within design specifications across different cabinet door openings, and finally document the valve position vs. airflow relationship curve.

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.

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.

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.

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.

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.

Yes. Maintain a certain length of straight pipe section before and after the valve, avoiding immediate proximity to flow disturbance components such as elbows, tees, and diameter reducers, otherwise, airflow turbulence at the vane will affect airflow measurement and regulation stability, and also increase noise. For systems requiring high airflow control accuracy, the valve installation location and straight pipe section length should comply with automatic control design requirements. Additionally, reserve maintenance space near the actuator, use shielded wires for control signal lines and connect them according to polarity, and verify that the signal range matches the actuator settings before power-on.

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