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The EHEDG (European Hygienic
Engineering & Design Group,
Brussels) is a joining together of experts from the equipment manufacturers
and the food industry who jointly developed design criteria for the
hygienic design of apparatus and components for food production.
CHETRA®
Mechanical Double Seals, Style 541 S/L are utilised for the
dynamic sealing of the shaft of Agitator vessels in the food- and pharmaceutical
industry and are laid out for CIP- and SIP-processes.
The
Chair of Process Engineering (Lehrstuhl für Maschinen und
Apparatebau) of the Technical University Munich in Weihenstephan
is the German accreditation body for hygienic testing in accordance
with EHEDG criteria, whom we asked to verify the design of the mechanical
seal style 541 S/L with regards to its hygienic design. For this purpose,
a mechanical seal style 541 S/L-050 (refer drawing) was provided.
Result of the Verification
Basically
it can be stated, that the design of the Mechanical Seal is in accordance
to the recommendations of the EHEDG corresponding to hygienic design
criteria. Especially the product contact area is designed to be easily
cleanable. Also the barrier flush-chamber shows no inadequacies with
regards to hygienic design.
Summary
The
subject appraisal showed that the double-Mechanical Seal, Type 541S/L
manufactured by CHETRA GmbH, Garching-Hochbrück, meets all the
hygienic criteria for easy cleanability (Hygienic Design Criteria).
The underlying EHEDG documents no. 8 and no. 25 are reflecting the current
state of the art.
The
mechanical seal is hygienically designed without any crevices and recesses.
Due to the avoidance of dead areas and the good surface finish, product
residuals are prevented. All construction materials used for the mechanical
seal are approved for the contact with food and have a higher corrosion
resistance, as well as a better temperature resistance. The double mechanical
seal could be used for aseptic applications because of the flushing
chamber.
Note:
Above is an excerpt of the verification of the mechanical
seal regarding cleanability according to EHEDG criteria. Detailed information
is given in the 12-page report (No. 89/24.08.2004) of Sept. 28/2004.
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