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Choosing the right &#;O&#; ring material can be the difference between a durable and reliable seal or one that very quickly fails, leading to costly unexpected downtime. FKM and EPDM are two common seal materials noted for their reliability. But what is the difference between FKM and EPDM? TRP Polymer Solutions explains all in this FKM vs EPDM comparison.
FKM and EPDM are both exceptionally durable materials, offering excellent thermal and oxidation resistance. However, there are some differences between these two types of polymer, as we outline below.
Fluoroelastomers (FKM) are characterised by their strong carbon-fluorine bonds, which give them the advantage of exceptional chemical, thermal and oxidation resistant properties. FKM also offers a wide operational temperature range of -45 °C to +204 °C, has good mechanical properties, and its density gives a high-quality feel. Find out more about the chemical structure of FKM here.
FKM is suitable for explosive decompression, CIP, SIP and FDA applications. It is ideal for applications involving the handling and transportation of chemicals and fuels, as well as high temperature and explosive environments like in the oil and gas, automotive and aerospace industries.
On the downside, FKM is known to swell in fluorinated solvents and cannot be used with molten or gaseous alkali metals. FKM rubber is a premium product, due to its chemical makeup and subsequent chemical resistance. So for that reason it does come with a higher price tag than other non-fluorinated hydrocarbons and low temperature grades can be especially costly.
Choosing the wrong grade of FKM can lead to rapid failure, which is why it is imperative to seek advice when considering FKM for an application.
Ethylene-propylene diene monomer (EPDM) is a durable and versatile synthetic rubber. Offering excellent resistance to ozone, sunlight and weathering, EPDM is a particularly useful material for outdoor applications. Few rubbers can withstand extremely cold temperatures like EPDM does. With an operating temperature as low as -50 °C (with highs of +150 °C), EPDM is a solid choice in sub-zero temperatures.
EPDM compresses well and is highly resistant to tears, abrasion and steam. Its all-round durability has seen it employed across a wide range of applications, including &#;O&#; rings, automotive cooling systems, and as insulation in freezer room seals. Although EPDM offers good resistance to dilute acids, ketones and alkalis, it does not fare so well fuels, oils and non-polar solvents. It certainly wouldn&#;t be a suitable choice for petro-chemical applications.
For a low-cost sealing material that has all the characteristics needed to perform in outdoor applications, then EPDM is a great value choice. This durable synthetic rubber won&#;t degrade when exposed to UV and will even tolerate prolonged contact with steam and some acids.
However, if your application demands the highest standards of chemical, thermal and oxidation resistance &#; and budget is not your primary concern &#; FKM is a premium product that will more than repay your investment.
We hope this FKM vs EPDM comparison has given you a better idea of each material&#;s advantages and disadvantages. We must stress that the best way to select the most appropriate material for your application is to speak to an expert who can talk you through the various material grades and match you with the ideal solution.
TRP Polymer&#;s technical experts have many years of experience developing and specifying high performance sealing materials and are only too happy to offer their guidance and advice. Speak to one of our experts today on or .
Are you interested in learning more about FKM Oil Seal? Contact us today to secure an expert consultation!
October 27, &#; by Eastern Seals
O-rings can be used in many applications as they are manufactured from a wide range of materials. O-rings are usually made from rubber, or more specifically, polymers / elastomers. These polymers are usually cured by vulcanisation which results in strong, durable and more elastic rubber materials.
Because of the wide range of materials available, it can be difficult to determine which is the most suitable for a project. It&#;s important to remember that different materials have different properties; For example, some are more elastic and others are more tear resistant in addition to other key qualities.
Viton® / FKM and NBR are two of the most commonly used elastomers for sealing applications, and for good reason. Both of these materials are suitable for general purpose applications. They offer excellent compression set resistance, and both are designed to resist most oils and lubricants, especially petroleum-based lubricants. Additionally, moderate temperature applications between -15°C and 110°C are served by both compounds, making either material a very good choice for general industrial use.
However, for more specific applications, the decision on material becomes much more important. Viton®/ FKM and NBR compounds have several very crucial differences that make them well-suited to certain applications. While both Viton/ FKM and NBR seals act as very good sealing options at moderate temperatures, Viton®/ FKM is far superior for high temperature applications.
Standard Viton®/FKM compounds can provide continuous sealing at temperatures up to approximately +205°C.
Standard NBR on the other hand is only effective for continuous sealing at temperatures up to +110°C (with short term sealing at 130°C.)
At temperatures below -20°C, standard Viton/FKM seals are less effective as they become quite hard and inflexible. Special Viton® / FKM compounds can provide low temperature capabilities of -40°C.
Standard NBR will operate successfully at -35°C (However, some special NBR compounds can provide effective sealing down to temperatures of -55°C,)
In addition to temperature, other application conditions differentiate these two compounds. Viton® /FKM has a wide chemical resistance range, which makes it ideal for most applications involving oils, fuels, and mineral acids. Viton®/FKM also offers excellent resistance to oxidation, ozone, UV exposure, weather, fungus and mould. Although NBR also supports some of the same chemical resistances, it is much less universally resistant than its Viton®/FKM counterpart, suffering degradation from weather and ozone exposure. For most circumstances, however, this may not be an issue. NBR also offers the benefit of superior abrasion and tear resistance making them better suited for more heavy duty industrial applications.
Both of these elastomers are suited for an extensive list of diverse applications, and they serve as excellent general purpose seals. Nevertheless, to optimise your choice in seals it is essential to consider the advantages and disadvantages of both materials.
Eastern Seals also supply a wide range of specialist grade Nitrile and Viton® / FKM seals. These include NORSOK approved materials, metal detectable seals, FDA approved compounds and low temperature grades.
For more information, expert consultation or a quote on Viton® / FKM or Nitrile seals, please contact our technical Sales team. Call +44 (0) or .
Contact us to discuss your requirements of NBR Oil Seal. Our experienced sales team can help you identify the options that best suit your needs.