API Plan 14

API Plan 14

Recirculation from pump discharge through a flow control orifice to the seal and simultaneously from the seal chamber through a flow control orifice to pump suction.

A  Flow control orifice

Seal chamber details

1  From pump discharge
2  To pump suction
3  Flush inlet (FI)
4  Flush outlet (FO)
5  Quench (Q)
6  Drain (D)
7  Seal chamber

Example seal: EagleBurgmann LEK777 single pusher mechanical seal.

P&ID according to API


  • Plan 14 is a combination of Plan 11 and Plan 13.
  • Acts as a flushing as well as a self-venting plan.
  • Cool fluid enters from Plan 11 piping, and hot fluid as well as seal chamber pressure is relieved through Plan 13 piping.
  • The flush is directed onto the seal faces.
  • Allows creation of sufficient vapor pressure margin independent of throat bushing design.


  • Generally used on vertical pumps.

Remarks, checkpoints

  • Orifice size should be at least 3 mm (1/8").
  • The flow of the flush fluid across the seal chamber must be sufficient to remove the heat and increase the pressure. Orifice size to be calculated carefully to ensure desired flush flow-rate.
  • Not applicable if difference between seal chamber pressure and suction pressure is very low. In this case Plan 13 is recommended.
  • A high-point vent must be provided in the vertical pump seal chamber (or seal gland) to ensure seal faces never see vapors.

Pump media characteristics

  • Clean, non-polymerizing fluids with moderate temperature.
  • Light hydrocarbons.

Location, function

  • Process side
  • Flushing and cooling



3CW-BB*, 3CW-FF*

* Remark: The configurations listed for each individual piping plan are to be understood as recommendations including possible utilizations which may also be applied.


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