Best Practices: Elastomer Sealing Systems for Ultra-Pure Water, CIP and SIP

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DÜPERTHAL Sicherheitstechnik GmbH & Co. KG

Both the EPDM and the FEPM substance have been successfully tested for WFI capability by a highly regarded pharmaceuticals firm, and have received certification to this effect from the Ecolab company, one of the leading producers of CIP media. The compounds also make a convincing impression when used in connection with SIP processes, so covering most applications in the relevant industries. The EPDM compound AP 302 has been specially designed for use with liquid or slightly fatty media. It can be used at temperatures ranging from -40 to +150 °C. If the fat content of the media used is in excess of 30 percent, use of the FEPM sealing substance Vi 602 is recommended. This also has excellent resistance to aromatic substances and etheric oils, and can be used at temperatures ranging from -10 to +230 °C.

Temperature Dependence of Elastomers

Generally speaking, designers and users need to take account of the fact that the resistance of elastomer sealing materials is going to depend on the actual temperature of use. It is quite possible for a substance to have positive resistance to the medium to be sealed in a lower temperature range, but to lose this resistance when the temperature is significantly higher.

Consequently it is difficult to make a flat and unreserved statement about the suitability of such materials. COG frequently tests its substances in close cooperation with its customers or with experienced professional companies, with the aim of achieving the most meaningful test results.

For the test with WFI, test rings were installed and tested on the existing system of a highly regarded pharmaceuticals company. The FDA-approved silicon seals that had been used in the past were being damaged in a short space of time, and had to be regularly replaced every two weeks. The tested substance Vi 602 was designed as a sterile seal and installed accordingly. The replacement interval was significantly prolonged, representing an optimisation of the system in terms of both ease of maintenance and economy.

This kind of reference test is of essential importance to users and designers, amounting to key documentation for the material, as the results of such trials reveal to the professional the fundamental suitability of the substance for the use envisaged. Consequently these tests are as a rule sufficient, and the sealing substance can be used directly without the need of further elaborate trials. But if the substance is to be used in borderline areas or with considerable deviations in relation to the test parameters, the competent advice of an applications technician is an essential recommendation.

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