This 3/4 in calibrated pressure relief valve is used in commercial, residential and industrial applications to protect against excessive pressure in systems containing water, oil, or air. It consists of a bronze body construction with NPT threaded male inlet and NPT threaded female (drain) outlet connections, stainless steel spring, brass bonnet, Buna-N disc, and Buna-N O-ring. It has a calibrated adjustment feature for setting the valve to the required relief pressure, and is ideal for by-pass thermal expansion pressure relief (not ASME approved). It is for use in fire protection systems. The maximum pressure is 300 PSI (20.67 bar). The adjustable pressure range is 100 to 300 PSI (3.45 to 12.06 bar).