WWT218803, Watts, 2 1/2 Pressure Relief, Sustaining Or Backpressure Control Valve, Thread

This 2 1/2 IN threaded pressure relief, sustaining or backpressure control valve is designed to permit flow when upstream pressure is above the adjustable set point of the control pilot, and throttle toward closed when upstream pressure falls below the adjustable set point. When installed off the main line on the branch of a tee it serves as a pressure relief valve. It is normally closed and quickly opens when upstream pressure exceeds the pilot setting, relieving excess pressure. When the valve is installed in line connecting two distribution zones, it serves as a pressure sustaining control valve. When pressure in the upstream zone falls below the pilot setting it modulates toward a closed position sustaining pressure in the upstream zone. When the valve is installed in line on the discharge of a pump is serves as a backpressure control valve. When pump discharge pressure falls below the pilot setting it modulates toward a closed position increasing backpressure against the pump.