Kunkle 171

Carbon steel non-code liquid relief valve with a stainless steel seat and disc and a pressure-tight hood. The baseline model of the line: 1 to 400 psig and −20°F to 550°F, FNPT 1/2″ through 2″, relieving 1 to 374 GPM at 25% accumulation. The A216-WCB body gives considerably more pressure and temperature headroom than the cast iron 71S while costing less than the all-stainless 171S. Trim is stainless throughout — A479-316 nozzle (A351-CF8M at 1-1/2″ and 2″), A743-CF8M disc, A313-316 spring. Non-code: no ASME stamp, no National Board certification. Maximum back pressure 50 psig. For a manually testable valve, specify the 171P; for corrosive or sanitary service, the 171S.