Expansion Chamber


An expansion chamber is screwed into the filling/vent connection of the pump bearing case. It is used with positive face seals for bearings to keep a positive pressure in the bearing case.


Without this expansion chamber a typical pump bearing case would build up about 15 psi. (1 bar) pressure when sealed with the newer positive face seals. With the expansion chamber the pressure is held to about one psi.


This positive pressure will keep moisture from entering the bearing lubrication.

  • The rubber diaphragm is often manufactured from Buna N material or any appropriate elastomer.