Plan 53A


Pressurized barrier fluid circulation system


  • Circulation is maintained by a pumping ring when equipment is energized, by thermosiphon effect when idle
  • No media leakage to atmosphere (provided system pressure is maintained)
  • Works as a Plan 52 system in the event of barrier pressure loss
  • Heat can be removed by a cooling coil in the seal pot
  • Seal life optimized by maintaining clean fluid film between the seal faces

For use:

  • Where no leakage to atmosphere is allowed; hazardous, flammable, toxic fluids
  • For dirty, abrasive or polymerizing fluids where media is unsuitable as a lubricant for the inboard seal faces




  • There will always be some leakage of barrier fluid into product – verify compatibility
  • Pressure in the seal must remain higher than pressure in the seal chamber (process) to avoid dilution of barrier fluid
  • Vent the system properly before start up
  • Inert gas can dissolve in the barrier media in certain cases
  • Barrier fluid contamination can cause corrosive degradation of equipment