Emerson Fisher 3/4 in. MNPT External Relief Valves for ASME Containers - 250 PSIG

Emerson Fisher
3/4 in.
Start-to Discharge Pressure:
250 PSIG
Flow Capacity:
2223 SCFM
0.40 LBS
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UL Listed external relief valves used on ASME containers. The relief valve is held close by the spring force seating the rubber valve disc against the orifice. When the tank pressure exceeds the spring force, the valve disc lifts off the orifice allowing gas to discharge through the valve to the air. When the tank pressure decreases enough, the spring force closes the valve disc back against the orifice stopping further discharge. All working parts of theses valves are outside the container connection so they must be protected against mechanical damage.


  • Space Saving Construction: Small relief valve size allows installation where space is limited
  • Economical: Low initial cost, easy installation, and high capacity per dollar invested reduces total cost of having relief valve capabilities in your system
  • Durable: Brass body construction and stainless steel spring reduce susceptibility to corrosion damage and the preset, pinned spring retainer prevents relief valve setpoint tampering


  • Container Type: ASME
  • Container Connection: 3/4 in. MNPT
  • Start to Discharge Pressure: 250 psig (17.2 bar)
  • Flow Capacity: 2223 SCFM (3777 SCMH AIR)
  • Maximum Allowable Relief (Inlet) Pressure: 420 psig (29 bar)
  • Temperature Capabilities: -20 to 160°F (-29 to 71°C)
  • Body, Poppet & Spring Retainer: Brass
  • Disk: Nitrile (NBR)
  • Spring and Retainer Pin: Stainless Steel


Product Manual (PDF Download)
Product Bulletin (PDF Download)