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Anderson Greenwood Whessoe 4920A Pressure and Vacuum Relief Valves
Whessoe 4920A Pressure and Vacuum Relief Valves
Pilot operated valves capable of providing pressure and vacuum relief that pipe away to a closed header system


  • Pilot operation ensures accurate pressure and vacuum relief.
  • Choice of body materials.
  • Fully open at 10% overpressure, enabling setting close to MAWP/MAWV and minimizing tank emissions.
  • Leakage rate of 0.5 scfh (0.015 Nm3 /hr) or less at 90% of setpoint.
  • Modular design enables all components to be removed and replaced in-situ for quicker, simpler maintenance.
  • Optional ‘all-weather’ coating prevents frozen condensate build-up and sticking of vital components in cold weather applications.


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