This website uses cookies. Find out why they are used read our privacy policy. x
By browsing this website you agree to use cookie files, in accordance with the current browser settings.

What is a Constant Volume Flow Regulator?

Constant volume regulator CFR-PC-ABS

What is a CFR regulator?
Self-adjusting Constant Airflow Regulators also referred to as self-regulating and automatic air volume regulators without external power supply. Airflow rate is regulated by rotating damper blade or other elements that throttle airflow and are connected with spring to counteract closing torque. Closing torque depends on airspeed through the damper. Required airflow rate is set in a specific range, depending on airflow regulator size, by adjusting spring tension. constant airflow is achieved due to spring tension. The flap closes and opens in controlled range when pressure changes. 

Construction of Constant Volume Flow Regulator

Self-regulating volume regulators are set using airflow scale

How does it work?
The air is forced to pass through a predetermined space in which the plastic adjustable flap can change its position in accordance with a precisely specified airflow. Airflow is set with a screwdriver. When the air flow pressure is rising, the CAV damper automatically closes to maintain a steady airflow rate.

What is it made of?
Our model - CFR-PC-ABS - is made in PC/ABS plastics and in galvanised steel for sleeves in diameters 125 to 250 mm. A balance spring is made of stainless steel. Self-adjusting airflow regulator consists of the main body, lockable and adjustable plate and self-adjusting flap. The airflow direction is shown on the label located on the regulator’s body must be respected to ensure proper operation.

Construction of Constant Volume Flow Regulator

Construction of the CFR Constant Volume Regulator

Adjustable Constant Flow Regulator is designed to be mounted inside the ventilation duct to ensure a constant airflow within the pressure range from 50 to 250 Pa. It is used in supply and exhaust air ventilation systems and air conditioning systems. For high-pressure installations, there is a special version of a self-adjusting constant regulator - CFR-PC-ABS-HP is designed for installations with a higher pressure of 150-600 Pa. 

How to install it?
The CFR-PVC constant flow regulator is installed inside the spiral duct – both in vertical and horizontal system arrangements to obtain a constant airflow in low-pressure ventilation systems (rated between 50 and 250 Pa). When mounting in the horizontal position, follow the inscription "DOWN"("BAS") on the front of the regulator. The airflow regulator should be installed at a distance equal to at least 3 times the duct diameter from the air supply vent and at a distance equal to at least 1 time the duct diameter from the air exhaust vent.

Installation of CAV regulator in spiral ductwork

CFR-PC-ABS regulators are installed inside the spiral duct.
The volume regulators are equipped with seals that ensure the airtightness of the connection.


  • Cost-efficient (the lack of actuator, reduces the price of self-regulating dampers comparing to motorized air flow regulators).
  • External power supply is not required.
  • Quick and easy assembly.
  • Simple setting - calibration using a screwdriver.
  • Fire retardant plastics classified M1.
  • Compatible with rigid metal ductwork.
  • Bidirectional solution, meaning the valve can be flipped to change from exhaust to supply.
  • Available in various diameter sizes.
  • Airflow can be adjusted on site.
Air flow regulators catalogue
Air flow regulators for ventilation installations
download PDF file »