Gas sealing assembly

Claim 1

In a machine for handling gas including a stationary body, with a higher-pressure side and a lower-pressure side, a shaft extending through the body, and a respective bearing supporting the shaft at each side, each bearing being arranged at a spacing from the body, a sealing assembly comprising: a respective casing at each of the higher-pressure and lower-pressure sides of the machine and fixed with respect to the stationary body, each casing enclosing a portion of the shaft between the body and the respective bearing and each casing having annular chambers which are open towards the respective shaft portion, including a first chamber, a second chamber which is disposed between the first chamber and the respective bearing, a third chamber between the first and second chAmbers, a fourth chamber between the second chamber and the respective bearing, the casing at the higherpressure side of the machine also including a fifth chamber between the first chamber and the body of the machine; means for introducing a barrier-action gas under pressure into the first chambers; means for introducing an inert gas under pressure into the second chambers; means connected to the third chambers for producing therein a pressure which is lower than the pressure in the first and second chambers; a conduit connected to the fourth chambers and open for discharge at a position remote from the machine; and means for introducing into the fifth chamber gas being handled by the machine, from the lower-pressure side of the machine.