A water relief valve is designed to relieve excessive pressures in a water supply system. It is also used in the discharge line of a fire pump to limit the pressure developed by the pump. Approval specifications require that a valve, set to operate at 100 psi (690 kPa), will discharge the full rated pump capacity without permitting the pressure to rise above 125 psi (860 kPa). It is designed to permit the removal of all working parts without removing the valve from its pipe connections. Sufficient clearance of all moving parts prevents sticking and avoids faulty operation.