The practical and versatile pressure relief valve is used to maintain and balance the actual air pressure in the cleanroom and controlled  environment. Its working principle is: when the air pressure in the cleanroom exceeds the standard air pressure, the pressure relief valve automatically opens; and when it is lower than the standard air pressure, the valve returns to the closed state, thus playing a role in balancing the air pressure.  It can prevent noise and possible bursting caused by the squeeze of air pressure in the cleanroom.