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Swagelok Quebec Group

Your Authorized Swagelok Sales and Service Center

API Plan 53C

API Plan 53C Barrier Liquid Pressurized by Piston Accumulator

API Plan 53C circulates a pressurized barrier fluid between the inboard and outboard seals. The source of pressurization is a piston accumulator. Plan 53C is preferred for applications where the seal chamber pressure may vary during pump operation. A sensing line is typically run from the seal chamber into the piston accumulator, allowing for a constant pressure differential to be maintained. As with Plan 53A and Plan 53B, barrier fluid must be compatible with 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 an optional heat exchanger.

plan 53C 


  • Provides additional heat removal from inner seal when required
  • Is used with a dual seal arrangement when the seal chamber pressure can vary during pump operation
  • Is used with a dual seal arrangement when process leakage to atmosphere cannot occur

See page 39 of the Mechanical Seal Support Systems Applications Guide for additional details.


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