Murphy offers two types of diesel fuel line valves: check valves and pressure relief valves.
The CKV series check valves are in-line, one-way valves that prevent fuel from being siphoned back into an injector or injection pump which could delay a shutdown.
There are two types of check valves: CKV2336 and CKV1WPS. The CKV2336 has a 1/4 NPT threaded male connection on each end for connecting to fuel line fittings or hoses. The CKV1WPS check valve is typically mounted in the fuel bypass line of the last fuel injector. The CKV1WPS features a hollow bolt connection and a barbed, 1/8 NPT connection for flex hose or fitting.
The PRV series pressure relief valves, relieve overpressure in a fuel system usually caused by closing of a solenoid fuel valve.
The PRV50 and PRV70 have a 1/4 NPT threaded connection on each end for connecting to fuel line fittings or hoses.
Murphy Check Valves and Pressure Relief Valves enhance at the operation of diesel engine shutdown valves by reducing the time required for complete engine shutdown after the solenoid valve closes. The diagram to the right shows a typical installation using CKV check valves and PRV pressure relief valves. All valves are shown closed.
Check Valves close off the fuel return line(s) to prevent fuel or air from re-entering the injection system through the bypass line(s). Models CKV2336 (3) is an in-line valve. Model CKV1WPS (2) has a 21/64 in. (8 mm) banjo fitting that attaches to the return line of the final injector. All check valves allow fuel to flow away from the injectors but close to prevent fuel from flowing in the reverse direction.
The PRV50 and PRV70 (1) relieve pressure buildup in the fuel system that can cause fuel filter canisters to burst. When the solenoid valve closes to stop the engine, the fuel transfer pump will continue to produce pressure as the engine slows down to stop. This pressure buildup, if not relieved, can cause fuel filter canisters or gaskets to leak. PRV’s are installed in the bypass line from the fuel filter(s) to the fuel return line.