1. Mechanical pressure relief valve: This is a more common type. It works based on the mechanical structure principle of the spring and the valve disc. When the pressure inside the box reaches the preset opening pressure, the spring is compressed and the valve disc opens for exhaust. The mechanical pressure relief valve has a relatively simple structure and high reliability.

   
   

2. Electromagnetic pressure relief valve: The opening and closing of the valve are controlled by electromagnetic force. When the control system detects that the pressure inside the box exceeds the set value, an electrical signal is sent to the electromagnetic pressure relief valve to make it open for exhaust. The electromagnetic pressure relief valve has a fast response speed and relatively high control accuracy.

3. Proportional regulating valve: It can precisely adjust the opening of the valve according to the pressure signal in a certain proportion, so as to achieve precise control of the exhaust volume. It can more finely adjust the pressure inside the box.

4. Pilot-operated pressure relief valve: It consists of a pilot valve and a main valve. The pilot valve senses the pressure change. When the pressure reaches the set value, the pilot valve acts to open the main valve for exhaust. The pilot-operated pressure relief valve is suitable for the exhaust control scenarios with large flow and high pressure.