RELIEF VALVES

Fire protection relief valves are safety devices designed to automatically discharge water when system pressure exceeds a predetermined limit, preventing damage to piping, fittings, and equipment. They serve as critical overpressure protection components in both standpipe and sprinkler systems. In accordance with NFPA 14, a main relief valve is installed on the system riser or at the discharge of a pressure-regulating device to protect the standpipe system from excessive pressure. These valves are typically larger, pilot-operated, and capable of relieving high flow rates to maintain system pressure within limits, especially in high-rise or pump-supplied installations.

By contrast, smaller relief valves—commonly ½-inch or ¾-inch—are installed on sprinkler systems downstream of zone control valves or within wet systems supplied by fire pumps. These direct-acting valves discharge limited volumes of water to relieve thermal expansion or minor pressure surges when the system is static. While both valve types perform pressure relief functions, main relief valves protect entire systems under flow conditions, whereas smaller valves protect localized zones or piping segments under non-flow conditions.