Series 374A Boiler Pressure Relief Valves are used in hot water boiler applications to protect against excessive pressure on all types of hot water heating boiler equipment. They have an iron body construction with forged bronze inlet connections, non-metallic disc-to-metal seating stainless steel spring, and test lever. Series 374A resists corrosive water conditions, sticking and freezing, and prevents water and sediment from being trapped in the seat. It is designed for emergency safety relief and shall not be used as an operating control.