Kunkle Models 230/330/330s/333s Relief Valves

Safety And Relief Products

Relief valves for air and gas services with models to ASME section VIII, gas ‘UV’, National Board certified and PED certified for non-hazardous gas


  • Lightweight aluminum construction is resistant to environmental and internal corrosion.
  • Repetitively consistent opening pressure.
  • Smooth relief action.
  • Positive reseating with minimal pressure drop.
  • Soft seat option provides repeatable leak-tight performance; allows reduced maintenance costs, multiple cycles with tight shut-off and high seating integrity (Models 330, 330S and 333S).
  • Model 230 (non-code) is direct spring-loaded design with synthetic disc insert.
  • Model 330 series’ differential mechanism maintains a predetermined seat contact load.
  • Full spring load is never imparted to synthetic disc insert (Models 330, 330S and 333S).
  • Seat tightness increases as inlet pressure approaches set (opening) pressure.
  • Each valve tested and inspected for pressure setting and leakage.

General Application

These valves are suitable for use on multistage high pressure compressors, intercoolers and aftercoolers; on high pressure receivers and storage bottles, for thermal expansion relief and on breathing air pac and SCUBA recharge compressors.

Technical Data

Connections: Threaded NPT or SAE
Temperature range: -20 to 185°F (-29 to 85°C)
Pressure ranges
Model 230: 300 to 1500 psig (20.7 to 103.4 barg)
Model 330 1000 to 5500 psig (69 to 379.3 barg)
Models 330S/333S: 1000 to 7500 psig (69 to 517.1 barg)
Max. back pressure
(Model 333S): 100 psig (6.9 barg)[1]
Codes: ASME VIII and PED
1. Back pressure reduces set pressure on a one to one basis and reduces capacity. Back pressure in excess of 10% of set pressure is not recommended.