During granulation in tablet and powder production, vacuum dryers are used which rotate relatively slowly (approx. 5 – 30 min). In addition, their stirrer shaft changes the direction of rotation at short intervals. In most cases, these systems are operated with deionised water as a sealing medium for the double mechanical seal used.

Under these conditions, conventional, liquid-lubricated double mechanical seals squeal. This is an indication of the increased wear on the seal faces and the associated reduced service life and also a considerable noise nuisance. CHETRA's specially developed Active Lub System prevents this lack of lubrication by supplying the optimum amount of liquid via appropriate feed zones and channels. The innovative Active-Lub System extends the service life of the mechanical seal.

During the production changeover at the premises of an internationally active pharmaceutical group, a vacuum filter dryer was to be used to produce a new drug that removes excess iron from the body. For this production process a special adaptation of the mechanical seal was required.

CHETRA designed a gas-lubricated double mechanical seal (Type 577 G) with a bellows to absorb the axial movement: fully CIP and SIP capable using FDA-approved materials and "iron-free" steel parts in special alloy. In addition, the mechanical seal was adapted exactly to the existing conditions, so that a problem-free conversion to the new seal was possible.