(833) 609-0173

API Plan 72

Externally supplied buffer gas maintained at a pressure less than the seal chamber pressure.

API Plan 72


This plan uses an externally supplied, low-pressure buffer gas (usually nitrogen) that is injected into the outer seal cavity. The injection process is regulated by a control panel for optimal results.

View Product View Product

Application Notes

  • Used in Arrangement 2 dual unpressurized seals, where the buffer medium is a gas. In normal operation, the buffer gas pressure should not exceed 10 psi [0.7 bar].
  • Plan 72 may be used alone or partnered with a Plan 75 (for condensing leakage) or Plan 76 (for non-condensing leakage).
  • Forward pressure regulator should be set to at least 5 psi [0.4 bar] above the normal flare pressure.
  • Most common buffer gas is nitrogen. Ensure a reliable supply and avoid the use of bottles if possible.
  • Buffer gas can be used to sweep inner seal leakage away from outer seal into a collection system and/or dilute the leakage so the emissions from the containment seal are reduced.
  • Ensure vent port is oriented to the 12 o’clock position and the drain is oriented to the 6 o’clock position.
  • Buffer gas can act to prevent icing in cryogenic applications.


  • Reduction in fugitive emissions due to the buffer effect of nitrogen
  • Prevention of icing in cryogenic applications
  • This plan provides some cooling at the outboard seal


  • Loss of buffer gas will cause a rise in emissions

Request a Quote