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API Plan 66B


Orifice plugs in drain port restricts seal leakage in event of seal failure. Pressure increase detected by pressure transmitter.


  1. Normal leakage passes through orifice plug to drain.
  2. Excess leakage is restricted by orifice plug from leaving seal gland causing pressure increase, which is sensed by the pressure transmitter.
  3. Leakage is directed to liquid recovery system or sump.


  1. Intended for use with arrangement 1 seals where it is required to limit leakage in case of seal failure.


  1. Drain connection must be at the bottom position.