Pressure Relief Valve

  When the pressure inside the equipment or pipeline exceeds the set pressure of the pressure relief valve, the pressure relief valve automatically opens to ensure that the medium pressure inside the equipment and pipeline is below the set pressure, protecting the equipment and pipeline and preventing accidental losses.

   working principle: 

The pressure relief valve is composed of needle valve I, pressure gauge 2, main valve 3, pilot valve 4, and connecting pipe and other components. It is a type of hydraulic control valve. The main valve is divided into upper and lower parts by a diaphragm. The lower chamber of the diaphragm is the water flow channel, and the upper chamber is the control chamber, which controls the opening and closing of the main valve disc. The pilot valve itself is a pressure relief valve, which also has a control room and a water flow channel. The opening and closing of the valve disc is controlled by the control room. Needle valve, also known as throttle valve, controls the flow of water in the connecting pipe. During the operation of the fire water supply system, the direction of water flow in the main pipeline is from left to right, and the control water enters the pilot valve control room. When the pressure of the water is less than the set pressure relief value, the thrust of the pilot valve spring is greater than the pressure of the water, and the pilot valve disc is in the closed state. The other way controls the water to enter the upper chamber of the main valve through the throttle needle valve, generating a static pressure. The pressure in the upper chamber is equal to the pressure in the raw flow channel. Due to the fact that the upper plane of the main valve disc is greater than the lower plane, the pressure of the upper chamber on the disc is greater than the push of the water on the main channel, causing the main valve to be in a closed state. If the water flow pressure in the main pipeline increases and exceeds the set pressure relief value, the water flow pressure entering the conduit control room through the control pipe increases, and the water pressure is greater than the spring thrust. At this time, the pilot valve is opened and the pressure relief begins on the main valve. Due to the control of the throttle valve, insufficient water replenishment caused a decrease in pressure in the upper chamber of the main valve, resulting in bone marrow ice under the same valve. The flow thrust is greater than the upper chamber pressure, the valve disc rises, and the main valve opens quickly to release pressure. Due to the instantaneous completion of the above process, the indoor fire water supply system will not cause harm in the event of overpressure. If the water flow pressure in the main pipeline continues to increase, the opening amount of the pilot valve will also increase. This will increase the pressure difference between the upper and lower chambers of the main valve, and the opening amount of the main valve will also increase, resulting in faster system pressure relief. On the contrary, if the water flow pressure in the main pipeline decreases (such as when the number of indoor fire hydrants used increases or the number of nozzles opened increases), the pressure in the control room of the pilot valve decreases accordingly, and the opening amount of the pilot valve decreases. The pressure in the upper chamber of the main valve increases, and the valve disc of the main valve closes smaller, stabilizing the water flow pressure in the main pipeline at the system design.