Pressure relief valves are installed to maintain a certain indoor static pressure and achieve a positive pressure in air conditioning rooms without energy consumption, providing automatic control.

It is a one-way adjustable air volume device, which adjusts the opening degree based on static pressure difference and balances the air pressure by the position of a heavy hammer. The air volume through the residual pressure valve is generally between 100-1200 m³/h, maintaining a pressure difference of 5-40 Pa.

The pressure relief valve has excellent adaptability to abrupt static pressure changes. It is generally recommended to be installed on the downwind side of the exterior wall between cleanrooms with different static pressure differences, and should not be placed in areas that would significantly affect the indoor air flow on the downstream side. The device consists of an outer frame, a valve plate, and a counterweight, with the valve plate opening angle at 45°. It is widely used in clean rooms or clean workshops to maintain a positive pressure difference between the indoor and outdoor environments, allowing excess indoor air to be expelled and preventing outdoor air from intruding.