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Swagelok Quebec Group

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API Plan 53B

API Plan 53B Barrier Liquid Pressurized by Bladder Accumulator

API Plan 53B circulates a pressurized barrier fluid between the inboard and outboard seals. The source of pressurization is a bladder accumulator. Plan 53B has the advantage of not allowing gas absorption into the barrier fluid which may allow for operation at higher pressures than Plan 53A. Barrier fluid pressure should be monitored as an indicator of seal performance. Leakage of barrier fluid will occur across the inner seal face and pass into the process. For this reason, the barrier fluid must be compatible with the process fluid and some level of process dilution be acceptable. In order to provide positive circulation through the support system and into the seal, a pumping ring is employed. Heat removal is achieved by using a heat exchanger.

plan 53B 


  • Provides additional heat removal from inner seal when required
  • Is used with a dual seal arrangement when process leakage to atmosphere cannot occu

See page 35 of the Mechanical Seal Support Systems Applications Guide for additional details.


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