You have probably seen both Teflon™ and Viton ® (FKM Fluoroelastomer) rubber mentioned when looking at o-rings and gaskets. They are both considered premium materials to be used in seals, so what are the differences? Let us start by taking a look at their composition.
Both materials are fluorinated to improve chemical resistance. Viton ® (FKM Fluoroelastomer) gasket material is a partially fluorinated elastomer, while Teflon™ is a synthetic fluoropolymer of tetrafluoroethylene. What does that mean? They use different chemical formulas to make materials with similar, but different applications.
Let us examine some of the differences.
Viton ® (FKM Fluoroelastomer) rubber is designed to withstand temperatures that range from -15 degrees Fahrenheit up to 437 degrees. It can withstand temperatures up to 600 degrees for limited amounts of time.
Teflon™ has a wider range of temperature usage. It can withstand temperatures down to -250 degrees Fahrenheit and up to 450 degrees. The top end temperature difference is nearly the same, but the low end temperatures make Teflon™ more suitable for extreme cold applications.
Teflon™ has an extremely low coefficient of friction. In layman’s terms, it is slippery. Teflon™ also has good wear resistance.
Viton ® (FKM Fluoroelastomer) Rubber does not have the low coefficient of friction like Teflon™, but is equal or superior in wear resistance. It is considered superior in compression set resistance, resilience, and permeation resistance. What does all of that mean? It means it bounces back into shape more consistently, it stands up to wear well, and prevents chemical from soaking into it.
Where are the two materials commonly used?
Both materials are used in o-rings, gaskets, and seals, but where they get used is what separates the materials.
Viton ® (FKM Fluoroelastomer) Rubber is used for vacuum seals, in applications with acids, lubricants, petroleum fuels and oils, silicone oils, and with many varieties of chemicals.
Teflon™ is used in applications which need chemical resistance, fuel resistance, and a low coefficient of friction.
As you are starting to see, there is a lot of crossover between the two materials in applications, but cost is often the determining factor. Viton ® (FKM Fluoroelastomer) rubber is less expensive than Teflon™ making it the preferred choice when it can be used. But, let us continue examining the differences a little more.
Viton ® (FKM Fluoroelastomer) Rubber cannot be used for certain chemicals. A few examples include ketones, brake fluids, ammonia, acetone, or low molecular ethers. It is not recommended for use in hot water and steam applications, unless you choose specially formulated versions of Viton ® (FKM Fluoroelastomer) made for those purposes.
Teflon™ fails when it comes to working on equipment which might have burrs or need to be stretched to fit. Teflon™ o-rings and seals tear or break more easily in these situations.
What are some common applications for both types of seals? This is a great way to compare the materials in real life.
Viton ® (FKM Fluoroelastomer) Rubber is used for seals in the chemical processing industry. The aerospace industry relies on Viton ® (FKM Fluoroelastomer) seals in a variety of applications including in fuel delivery systems. The oil and gas industry use Viton ® (FKM Fluoroelastomer) seals extensively. One of the largest uses of Viton ® (FKM Fluoroelastomer) rubber is the automotive industry where fuel and oil systems rely on o-rings and seals made from Viton ® (FKM Fluoroelastomer).
Teflon™ seals are found extensively in the chemical processing industry, also. You will find them in chemical storage seals and gaskets in handling equipment.
How do you determine what is the best choice for your seals?
That is not always easy to determine. Teflon™ and Viton ® (FKM Fluoroelastomer) Rubber seals can often be used interchangeably in many industries. Viton ® (FKM Fluoroelastomer) wins in many of these applications due to its lower cost. Teflon™ is superior resistance to low temperatures and ability to resist a higher range of chemicals helps it keep a good market share in the industry, also.
When determining your needs, first evaluate the temperature guidelines. If you are running in a refrigerated environment look at Teflon™ as the preferred choice. Next compare the chemical resistance needs for your seals. If Viton ® (FKM Fluoroelastomer) meets both your temperature and chemcial resistance needs it will be the better choice. It is easier to work with, lower in cost, and is less prone to breakage due to stretching or nicks in the material.
Both Teflon™ and Viton ® (FKM Fluoroelastomer) are high-quality materials which have cemented their places in industry. While there are many similarities between the two materials, their differences are what will help you decide which is right for you.