This 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 is for use in fire protection systems. 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. Series 530C 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). The maximum pressure is300 PSI (20.67 bar). The adjustable pressure range is 50 to 175 PSI (3.45 to 12.06 bar).