Air volume control dampers enable regulation of supply or exhaust air volume in ventilation systems. Constant air volume control damper maintain a constant air volume regardless of the pressure and do not use any additional power source for functioning. Constant air volume is enabled through a balance between the aerodynamic force and force of closing mechanism spring unaffected by air pressure changes inside the system. Depending on project requirements it can be controlled over temperature, quality, occupancy or some other sensor. Data about measured differential pressure is transferred to the motor mechanism where it is being compared with reference signal. Depending on the difference, mechanism is opening or closing the damper and assures the optimal air volume in the room. Rectangular and round air volume control dampers are available.