Viton® GF and ETP have broad resistance to chemicals and fluids that are often used in food flavorings.
At Holland, we have been selling sanitary process fittings into the high purity equipment market for over sixty years. By far and away the most popular sanitary union is the Tri Clamp flange. We have spent numerous posts discussing this union. We’ve also spent a great deal of time discussing materials and material selection in difficult applications. This is a topic we will revisit today, discussing some specialty Viton ® sanitary gaskets designed to deal with problematic conditions often presented in pharmaceutical and food applications.
Historically, pharmaceutical and food manufacturers have often used EPDM or silicone gaskets. Reasoning behind material selection has varied. EPDM provides excellent resistance to steam, while silicone is very resistant to a wide variety of cleaning fluids used in CIP cycles. Silicone, however, is not good in steam applications and EPDM struggles not only with fats and oils, but also common cleaning fluids.
As an alternative to EPDM, bisphenol-cured types of Viton® hit the market and made a name for itself in high purity process applications for their good thermal properties and wide ranging resistance to chemicals, especially fats and oils. These bisphenol-cured elastomers are superior to diamine-cured types of fluoroelastomers (FKM), but still had relatively poor resistance to CIP chemicals compared to silicone and didn’t perform quite as well as EPDM in steam applications. To combat these problems, DuPont™ has introduced Viton ® GF-600s and Viton® Extreme ETP-600s. Holland has access to standard Tri clamp gaskets in these materials through our business partners, Newman Sanitary Gasket.
Viton® GF-600s is a high-fluorine, peroxide-cure type of Viton®. Fluorine, an extremely reactive halogen with seven valence electrons, forms very strong ionic bonds especially with carbon (in organic chemistry it is actually referred to as the “strongest” bond due to the high electronegativity of fluorine). The higher levels of fluorine gives vulcanizates excellent steam resistance and superior resistance to a wide range of CIP chemicals.
Viton® Extreme™ ETP-600S is another unique fluoroelastomer that exhibits superior steam resistance and distinguishes itself from other elastomers by offering resistance to an exceptionally broad variety of chemicals including aliphatic and aromatic hydrocarbons, acids, bases, alcohols, and even low molecular weight ketones, esters, and aldehydes. These properties are very important in pharmaceutical applications where extractable and leachable contents are critical.
So what does this all mean and when should I use these two materials in my sanitary gaskets? Well, if you have an application where you SIP, or steam in place, you may want to consider Viton® GF-600s. Both GF-600S and ETP-600s have shown excellent retention of tensile properties with steam aging, outperforming even EPDM. Viton GF® offers a great alternative to Teflon in these thermally aggressive applications and still gives you the benefit of an elastomer gasket.
You will also see the benefits of these fluoroelastomers in CIP applications. We see significantly lower swell volumes in Viton® ETP and GF when treated with common acid detergents such as CIP 220 and Chematic 91 than we see in EPDM. In fact, ETP and GF perform comparably to silicone in these applications. Similar results are seen when looking at tensile properties of ETP and GF after treatment other organic acids, especially when compared to bisphenol-cured Viton®.
Another benefit to Viton® GF and ETP are the broad resistance to chemicals and fluids that are often used in food flavorings. When immersed in different soft drink flavoring concentrates for one week, GF and ETP significantly outperformed bisphenol cured Viton® and EPDM. In fact, Viton® ETP can be considered just below Kalrez® in performance.
Expanding on this, ETP and GF also have exceptionally low extractables and leachables, especially when compared to bisphenol cured fluoroelastomers. In order for bisphenol cured elastomers to properly cross link, a metal based acid acceptor, such as magnesium oxide and calcium hydroxide must be used, often at levels of about 6-9% weight of the total compound. GF and ETP do not require the addition of these materials and can be formulated in a manner that results in considerably lower levels of extractable metals when soaked and tested in WFI. Remember, WFI is extremely pure, ion hungry, and very aggressive. Extractable levels are lower than even EPDM, Platinum cured silicon, and PTFE sanitary gaskets.
To conclude, the sterilization processes used by pharmaceutical and food manufacturers commonly use steam, aggressive cleaning solutions, or a combination of both. These aggressive conditions are very demanding on the sealing materials used in these environments.
While EPDM provides excellent steam resistance, it is susceptible to attack by cleaning fluids. Silicone gives good resistance to a variety of cleaning fluids, but has relatively poor steam resistance. PTFE gives us good steam and chemical resistance, but doesn’t seal well.
Viton® Extreme ETP-600S and Viton® GF-600s have both been proven to give an outstanding combination of steam and chemical resistance while retaining the sealing properties of traditional elastomers. Additionally, they have excellent resistance to chemicals and fluids used as food flavorings and have significantly lower total organic carbon and total metals extractables.
They are USP Class VI and FDA CFR Title 21 approved. In partnership with Newman Sanitary Gasket, Holland is able to offer both materials in standard Tri clamp sizes ½”-4” and flanged sizes up to 10”. Contact Holland today for more information about our exciting range of fluoropolymer offerings.