API Plan 53A


Pressurised barrier fluid circulation in outboard seal of dual seal configuration through a seal support system. Circulation is maintained by using pumping ring in running condition and with thermosyphon effect in stand still condition.


1. In no case will media leak to atmosphere (Provided the seal support system pressure is not lost).

2. Clean fluid film formation between the inboard seal faces gives better seal life.

3. Works as a Plan 52 arrangement if barrier fluid pressure is lost.


1. Applications where no leakage to atmosphere can be tolerated e.g. hazardous, toxic, inflammable media.

2. For dirty, abrasive or polymerizing products where media is unsuitable as a lubricant for inboard seal faces.


1. There will always be some leakage of barrier fluid into the product. Check compatibility of barrier fluid with product.

2. Always ensure that the pressure source maintains higher pressure at the seal support system so that process does not dilute the barrier fluid.

3. Vent the system properly before start up.

4. In certain cases the inert gas can dissolve in the barrier media.

5. Product quality can deteriorate due to barrier fluid contamination.

API - 53 A 4th Edition 30 secs


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