Series 740 Boiler Pressure Relief Valves are 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 a 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. Series 740 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 and shall not be used as an operating control. Pressure Range: 30 to 75psi (2 to 5 bars) with corresponding high ratings from 925,000 to 10,700,000 BTU/hr. Size Range: 3/4 to 2 in. (20 to 50mm)