The Surge Relief Angle Valve (SRA) is an elbow body style surge relief valve that is held normally closed by a compression spring or system of nested springs. They are available in sizes 2-16″ (50-400mm) and with pressure relief ratings up to 200 psi (1380 kPa). SRA Valves are available in ductile iron with seats of Acrylonitrile-Butadiene (NBR), Terpolymer of Ethylene, Propylene and A Diene (EPDM) or Fluoro Rubber (FKM).
Surge Relief Angle Valves are designed to prevent damage from water hammer in the system by opening when the system pressure exceeds the set shut-off pressure of the valve disc. As the disc opens, the surge pressure rise that caused it to open is spilled and dissipated through the open valve. When system pressure drops below the set shut-off pressure, the valve disc slowly closes against the oil contained in the cushion chamber and cylinder. Surge Relief Valves are designed with a smooth flow and minimal obstruction to flow for efficient surge relief.
Pressure surges occur when fluid velocity changes. APCO Surge Relief Valves limit the surge pressure magnitude commonly associated with sudden pump shutdown in fluid piping systems.
The surge relief valve is typically installed downstream of the check or pump control valves on the pump discharge header with the valve inlet connected to the side outlet of a tee and the valve outlet piped to the sump.
The normally closed surge relief valve opens quickly when the system pressure rises above its adjustable relief pressure setting allowing fluid to be discharged from the system through the open surge relief valve to atmosphere. While the surge relief valve is open, the system is no longer contained, fluid compression is limited and surge pressure is controlled. The valve will remain open as long as the system pressure exceeds the valve’s relief pressure setting. The valve will slowly begin to close at an adjustable rate as the surge pressure subsides and the system pressure falls below the valve’s relief pressure setting.