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API Plan 22


Product recirculation from pump discharge through a Y strainer, a flow control orifice and a heat exchanger to seal chamber.


  1. Improves pressure margin over vapour pressure.
  2. Improves temperature margin to meet secondary sealing element limits, to reduce coking or polymerizing and to improve lubricity.
  3. Self venting plan.
  4. Provides sufficient pressure difference to allow proper flow rate.


  1.  For high temperature applications with slightly dirty liquid.


  1. Always ensure that the orifice is placed after the Y strainer.
  2. Always ensure that cooler is placed after the orifice. 
  3. Check pressure difference between discharge and seal chamber.
  4. Cooler duty is leading to fouling on waterside.
  5. This plan is normally discouraged due to non-reliability of Y strainer.

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