Ductwork Constant Air Volume Valve Cav for Ventilation System Flow Control

Regular Options:

CAV valve Used for Cleanroom HVAC & Ventilation System

** for maintaining a fixed airflow rate

A mechanical constant air volume valve, designed for maintaining a fixed airflow rate. It operates without the need for a DDC controller or actuator. This is a pressure-independent type of constant air volume terminal.

This device saves on-site commissioning time and is suitable for both new construction and renovation of air conditioning and ventilation systems.

Valve Body Characteristics

*   The constant air volume valve utilizes a flanged connection to the ductwork.

*   Compact design with low-pressure loss.

*   Factory-set value is displayed on the unit.

*   During ordering, specify the required airflow rate; each unit is individually calibrated and adjusted at the factory.

*   Material:

• Valve body- galvanized s
• Blade & Shaft - galvanized
• Shaft sleeve - polytetrafluoroethylene.
• Airbag - Polyurethane.

** Working Principle

Core Principle

A Constant Air Volume (CAV) valve is a “pressure-independent” device designed to maintain a “pre-set, constant airflow rate” regardless of fluctuations in the duct pressure upstream or downstream of the valve. It achieves this through a self-contained, mechanical control system that automatically adjusts an internal damper to compensate for these pressure changes.

Detailed Mechanism

The operation relies on a mechanical system typically composed of a “spring-loaded diaphragm” or a weighted lever, connected to an internal damper.

1.  Equilibrium at Setpoint: Under normal conditions at the desired airflow, the forces within the valve (e.g., the spring force) are in equilibrium, and the damper remains in a fixed position.

2.  Response to Pressure Increase: If the duct pressure increases, the heightened airflow attempts to force the damper closed. This action is sensed by the diaphragm or lever, which compresses the spring or moves against the counterweight. This movement automatically adjusts the damper towards a more closed position, increasing resistance to restore the original airflow.

3.  Response to Pressure Decrease: Conversely, if the duct pressure drops, the reduced airflow causes the spring to expand or the counterweight to readjust. This pulls the damper towards a more open position, reducing resistance and allowing the airflow to return to its setpoint.

In essence, the valve acts as an intelligent, self-correcting orifice. Any pressure change disrupts the internal force balance, triggering an immediate, proportional adjustment of the damper to maintain a constant cross-sectional area for airflow, thereby ensuring a consistent volume.

** Applications  in the duct of ventilation or air-conditioning systems for below industries:

- Pharmaceutical and biotechnology facilities.  

- Semi-conductor and chips processing and manufacturing plants.  

- Laboratories handling hazardous substances.  

- Hospital and medical ventilation system.

- Food and beverage production areas requiring odor control.