Kunkle Models 71S/171/171P/171S Liquid Relief Valves

Safety And Relief Products

Extra heavy, rugged construction non-code liquid relief valves with a variety of model options to meet specific applications


  • Suitable for back pressure to 50 psig (3.45 barg)[1].
  • Seats lapped for optimum performance.
  • Spherical pivot between disc and spring corrects misalignment and compensates for spring side thrust.
  • Stainless steel springs.
  • Tested and inspected for pressure setting and leakage.
  • All SS 316 model 171S suitable for sanitary applications, depending on requirements.

NOTE 1. Back pressure increases set pressure on a one to one basis, and reduces capacity. Back pressure in excess of 10% of set pressure is not recommended.

General Application

Suitable for overpressure relief, pressure regulation, by-pass relief and protection of pumps, tanks, lines and hydraulic systems containing acid, caustic, ammonia and other corrosive liquids requiring iron, steel or SS materials.

Technical Data

Connections: FNPT
Temperature range:
Model 71S: -20°F to 406°F (-29°C to 208°C)
Models 171, 171P, 171S: -20°F to 550°F (-29°C to 288°C)
Pressure range:
Model 71S: 1 to 250 psig (.07 to 17.2 barg)
Models 171, 171P, 171S: 1 to 400 psig (.07 to 27.6 barg)