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Swagelok Quebec Group

Your Authorized Swagelok Sales and Service Center

API Plan 72 Buffer Gas

API Plan 72 supplies a buffer gas from an external source between the inboard and outboard seals. For reliable operation, gas seals require a constant supply of clean, dry gas, typically nitrogen. The seal support panel contains a coalescing filter to remove any moisture and particulate present in the supply of plant nitrogen. The clean, dry nitrogen dilutes process leakage from the inboard seal and sweeps it to a collection system. For condensing leakage, a Plan 75 is used as the collection system; for non-condensing leakage, a Plan 76 would be used for the collection of primary seal leakage. A pressure regulator on the panel regulates the nitrogen prior to entering the seal chamber. Nitrogen pressure should not be more than 10 psi (0.68 bar) and is typically regulated

plan 72 


  • Supplies the gas seal with a clean, dry buffer gas, typically nitrogen
  • Serves as a containment seal in the event of primary seal failure

See page 51 of the Mechanical Seal Support Systems Applications Guide for additional details.


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