Holland Offers a Broad Variety of FDA Approved and USP Class VI Gaskets
One of the most common questions we get day in and day out is related to sanitary gasket material choices in some form or another. Every day we will have a customer call in and say, “Can I get price and availability of 25ea 1 1/2” gaskets”?”. Our customer service team, well-trained as they are, patiently ask, “Well what material would you like?”. Their response many times is silence and generally doesn’t exude confidence. If technically savvy users don’t always know why they use a specific gasket material, that’s just what they’ve always done. This post will give an overview of the most common sanitary gasket materials and the pros and cons of each material.
Nitrile Buna Rubber (U) – Buna rubber is by far the most common and economic food grade gasket material. Designated by a red dot, Buna is only recommended to intermittent temperatures of 240 F and continuous temperatures of 210 F. Most Buna rubbers do not carry Class VI compliance. While inexpensive, applications for Buna abound. They are great from use on ambient or potable water lines, and have good chemical compatibility with most moderately aggressive chemicals.
Fluoroelaster (FKM) – Also known as Viton, there are many different formulations and classes of Viton. Featuring yellow and white dots, FKM is an excellent choice in both CIP and SIP applications. While they aren’t as well suited for ultra-aggressive chemical applications, FKM handles oils, alcohols, acids, and alkalis with ease. Most are USP Class VI compliant and have max intermittent and continuous temperature s 410 F and 380 F respectively.
Platinum Cured Silicone (PX) – A favorite among pharmaceutical users, platinum cured silicone gaskets also exhibit silicone’s trademark low extractables and leachables profile. Platinum cured silicone gaskets have excellent high temperature properties. With chemical resistance to a variety of common chemicals, including acids, bases, and steam, the primary drawback is cost- likely the reason we see these primarily used in only ultra-high purity applications.
Ethylene-Propylene Diene Monomer (EPDM) – Along with FKM, EPDM is among the most commonly used elastomers for sanitary gaskets. Marked with green dots, EPDM offers excellent chemical resistance along with good thermal properties and attractive price point that make it a common elastomer choice in both pharmaceutical, personal care, and food applications. The biggest drawback to EPDM is the materials vulnerability to oil based products. Oil based products causes swelling and deformation of EPDM which can compromise the seal.
Polytetra Fluroro Ethylene (Teflon) – PTFE is worth mentioning in this post mostly for what it is not- an elastomer. PTFE is a plastic and exhibits little elasticity and memory. Due to the lack of “squish factor”, or compression, this leads to difficulty sealing, especially in larger sizes. That being said, the chemical compatibility and temperature ranges of PTFE are unmatched.
While there are additional polymers used in sanitary gaskets- what we call “designer elastomers”- such as Tuf Steel, Viton GF, Viton ETP, and Tuf Flex, the above provides a good summary of the elastomers we get questions about everyday. For help selecting a gasket material for your next sanitary application, contact a Holland Sales Engineer today.