Abstract: An agitator of impeller shape includes an agitator hub with a plurality of radially extending arms for attachment to a drive shaft for the mixing of substances in vessels, such as substances that tend to material build-up, incrustation and/or incipient polymerization. The hub is totally closed by welding a cap over the end of the hub. At least one of the agitator arms is formed of two components, a shorter stub arm attached to the hub and longer main arm. Both components are formed of a pair of parallel, spaced apart tubes connected by a pair of webs. Each tube includes a bushing for retaining a centering bolt to attach the main portion to the stub portion. The two components are then welded together and polished to remove any gaps and sharp edges.

Abstract: An apparatus and method for the continuous thermal sterilization of packings on rotating or reciprocating shafts to prevent the entry or exit of microorganisms, wherein the thermal sterilization of the packings results from a flow of steam condensate about the packings, characterized in that at least one part of the steam condensate is circulated in a closed cycle. As a result of circulating in a closed cycle, the required quantity of steam is reduced and energy losses are decreased. The apparatus and method are particularly useful for installations carrying out biological processes.