This boiler pressure relief valve is used in hot water space heating boiler applications to protect against excessive pressure on all types of hot water space heating boiler equipment. It consists of an iron body construction with expanded outlet drain connections for hot water space heating boilers, non-metallic disc-to-metal seating, stainless steel spring, and test lever. It offers large discharge capacity, resists corrosive water conditions, resists sticking and freezing, and prevents water and sediment from being trapped in the seat. It is designed for emergency safety relief, not as an operating control. The pressure relief is set at 40 psi