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

Author / Editor: Michael Krüger / Dominik Stephan

The market for ultra-pure water systems continues to grow. But for elastomer seals contact with ultra-pure water represents an extreme situation. This adds up to a major challenge for the manufacturers of sealing systems. The present article tells you what kind of sealing materials are capable of dealing with this situation.

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There is hardly any other sector where the requirements for modern high-performance sealing systems have risen so sharply in recent years as in the pharmaceuticals and foodstuffs industries (the picture shows a filling plant in foodstuffs production). (Picture: iStockphoto.com/graphixel)
There is hardly any other sector where the requirements for modern high-performance sealing systems have risen so sharply in recent years as in the pharmaceuticals and foodstuffs industries (the picture shows a filling plant in foodstuffs production). (Picture: iStockphoto.com/graphixel)

Especially in the pharmaceuticals industry and in biotechnology, demineralised water and Highly Purified Water or even WFI (Water For Injection, i.e. completely demineralised ultra-pure water) are increasingly coming to be seen as a standard requirement.

WFI stresses and damages materials because it tries to withdraw the minerals from the contact substances. It is even capable of making concrete porous and useless in a short space of time. Demineralised water is a preliminary stage of WFI, and is likewise used in production, but it is not quite so aggressive as WFI. Both media subject elastomer substances to extreme stress. Only few sealing materials are resistant to long-term contact with these media, while at the same time having the FDA and USP Class VI approvals that are required for systems of this kind.

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This is why users and designers are increasingly calling for documentation of the application-specific suitability of the materials, as well as certificates or definite statements about certain resistance properties of the sealing substances used. What is more, quite apart from general resistance to media, sealing substances must often also be suitable for use with current CIP and SIP (Cleaning In Place/Sterilisation In Place) procedures. The interaction between the media that are to be sealed and the sometimes very aggressive disinfectants or cleaning agents, or the scalding water vapour used in the sterilisation process (which may reach a temperature up to 149 °C), likewise subjects the materials to extremely testing conditions. Many elastomer seals cease to function in the long term. More frequent maintenance intervals and repairs, or even production stops, are the costly consequence.

Rising Requirements for Sealing Systems

The requirements for elastomer sealing systems in the foodstuffs and pharmaceuticals industries are becoming ever more complex. As a result of the increasing reduction or even abolition of conservants, impurities that occur in pipelines, valves, pumps and the like in the course of the production process need to be removed with more and more effective cleaning agents based on the CIP approach.

At the same time production cycles are being shortened in the interest of increased productivity, and cleaning processes likewise have to be cut short. Cleaning now tends to be carried on using even more aggressive CIP media. C. Otto Gehrckens (COG) has developed two substances specially for this area of applications: the EPDM substance AP 302 and the FEPM substance Vi 602, both of them approved in accordance with the requirements of FDA 21 CFR § 177.2600 and USP Class VI, Chapter 88. In the USP trial the substances were successfully tested in the highest class, at a temperature up to 121 °C, and not, as is generally the case on the market, just up to 70 °C. In addition, the EPDM compound meets the criteria of 3-A Sanitary Standard Class II.

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