Plan 21


Product recirculation from discharge through flow control orifice and heat exchanger to seal chamber


  • Can improve vapor pressure margin
    Cools the seal environment to reduce coking or polymerizing and improve lubricity
  • Self venting plan

For use:

  • For high temperature applications, such as water greater than 175°F, hot hydrocarbons, etc.
  • With hot, non-polymerizing fluids


  • Cooler must be placed after the orifice
  • Verify pressure differential between discharge and seal chamber
  • Cooler must be regularly de-scaled on water side
  • Potential plugging on process side if fluid viscosity increases rapidly
  • Can be very expensive in energy costs if process temperature must be maintained