The SV-Series valve is a normally closed valve that opens when current is supplied from the battery through a magnetic switch. Temperature, level, or pressure Switchgauge instruments installed on the engine and pump or compressor, trip the magnetic switch, breaking the circuit from the battery which closes the valve and stops the engine. The standard SV-12 valve operates on 12 volts DC, has a 1/4 NPT inlet and outlet, and a full 3/16 in. (5 mm) orifice. The standard SV valves open against 30 psi (207 kPa) [2.07 bar] inlet pressure.