A water pressure reducing valve is designed to limit system outlet pressure in a fire protection system. These valves are used in standpipe systems to actively regulate outlet pressures in both static and flowing conditions, and are required for outlets of systems where static pressure could exceed 175 psi (1207 kPa). Water pressure reducing valves employ an active mechanism that compensates for variations in inlet pressures by balancing water pressure in an internal chamber or chambers. Approval specifications require that a 3⁄8 inch or larger pressure relief valve must be supplied for installation with every water pressure reducing valve. The pressure relief valve must have an adjustment range of 50 psi (345 kPa) or less to 200 psi (1380 kPa) maximum. Approval Specifications also require that a position indicator or pressure gauges must be provided to give a visual indication of all conditions of the water pressure reducing valve, and that means shall be provided to lock or seal the pressure reducing valve at the adjusted pressure setting.