Kunkle 537 Safety Relief Valve — 3/4″ x 1″ FNPT, 15-160 PSIG (Hot Water ASME Section IV)

The Kunkle 537 is a safety relief valve for low pressure hot water boilers, heat exchangers and generators. It serves a dual purpose: relieving the overpressure created by thermal expansion under normal firing conditions, and the overpressure in the form of water or steam created by over-firing when electrical or other controls fail. Construction is extra heavy for long life, with a top guided disc assembly carrying a resilient seal in the seating area, an isolating diaphragm that protects the working parts from corrosion caused by discharged liquid, a pivot between disc and spring that corrects misalignment and compensates for spring side thrust, and a heavy duty lift lever. This 3/4″ x 1″ FNPT variant has an orifice area of 0.533 in² and relieves 690 to 4,219 lb/h (690,278 to 4,219,103 BTU/h) at 15 to 160 psig. Set pressure range is 15 to 160 PSIG (1.0 to 11 barg) over a temperature range of -20°F to 250°F (-29°C to 121°C). The 3/4″ size has a bronze B584 alloy 84400 body; note that the 1-1/2″ and 2″ sizes are cast iron. ASME Section IV and Section XIII code service with the ‘HV’ designator, National Board certified. Specify your required set pressure when requesting a quote.

↓ Kunkle 537 Datasheet (PDF)