Pressure Sustaining – Relief Function Angle – 7SPF
The Pressure Sustaining function positions the valve to maintain a minimum supply (upstream) pressure into the Main Control Valve. The pilot senses the supply pressure and opens on the supply pressure and opens the main valve until it reaches the pilot setting. The Main Control Valve then opens and supply demand into the system. Should the supply pressure reduce to the pilot setting, the pilot will close the Main Control Valve partially to maintaining a constant supply pressure. The Pressure Relief function relieves any excess pressure from the system. The pilot setting will be higher than the system setting, but within the safety pressure for the system. Should the system pressure increase, the pilot opens the main valve, relieving the pressure. Speed controls are fitted to allow the valve to open instantaneously and close slowly to prevent any pressure surges.