Sealing arrangement for rotatably mounted shafts

Claim 1

Sealing arrangement for a shaft rotatably mounted in a housing, and operable in abrasive media, comprising: a main seal and an auxiliary seal fitting around the shaft and extending between respective surfaces associated with said shaft and said housing, a chamber formed between the main and auxiliary seals by housing and shaft parts, said chamber being located at the side of the main seal closest to the auxiliary seal, a feed opening for continuously communicating a pressurized environmentally harmless separating medium to said chamber, an outlet opening in said chamber for the separating medium, and pressure medium supply means for supplying said environmentally harmless separating medium to said feed opening under pressure, said pressure medium supply means and the dimensions of the feed and outlet openings being correlated to one another to assure that a certain amount of the separating medium continuously escapes from the chamber through the auxiliary seal during operation of the shaft to prevent ingress of the surrounding abrasive media into the chamber, and wherein said outlet opening is provided at the point in the chamber which is lowest in the operating position of the sealing arrangement whereby pollutants which are in the chamber can be flushed from the latter.