Principle of Fire Protection Pressure Reducing Valve
When water flows through the valve, water flows into the main valve control chamber through the needle valve, and the outlet pressure is imposed on the pilot valve through the guide duct. When outlet pressure is higher than the set pressure of the pilot valve, the outlet pressure does not rise any more; when the outlet pressure of the valve reduces to the set pressure of the pilot valve, the pilot valve opens, water is discharged out of the control chamber. Because the water discharged from the pilot valve system is more than the water inflow, the pressure in main valve control chamber reduces. The inlet pressure forces the main valve open. In a stable state, the water inflow and discharged water of the control chamber are equal. The opening of the main valve keeps constant, with stable outlet pressure.