Advantages and disadvantages of FKM vs EPDM for ‘O’ rings

By June 15, 2022News

FKM and EPDM are common ‘O’ ring materials that offer excellent thermal and oxidation resistance. However, there are some significant differences between these two polymer materials, which, depending on your application, can make or break your choice of ‘O’ ring material. Here, TRP Polymer Solutions talks us through the various advantages and disadvantages of FKM and EPDM.

Advantages
FKM: 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.

EPDM: EPDM offers excellent resistance to ozone, sunlight and weathering. Few rubbers can withstand extremely cold temperatures like EPDM. 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.

Disadvantages
FKM: FKM is known to swell in fluorinated solvents and cannot be used with molten or gaseous alkali metals. FKM is a premium product, due to its chemical makeup. So it does come with a higher price tag than other non-fluorinated hydrocarbons and low temperature grades can be especially costly.

EPDM: 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.

Applications
FKM: FKM is suitable for explosive decompression, CIP, SIP and FDA applications. It is ideal for the handling and transportation of chemicals and fuels, as well as high temperature and explosive environments, such as in the oil and gas, automotive and aerospace industries.

EPDM: EPDM’s 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.

Verdict
FKM: 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.

EPDM: For a low-cost sealing material that performs well in outdoor applications, EPDM is a good choice. This durable synthetic rubber won’t degrade under UV conditions and will tolerate prolonged contact with steam and some acids.

Read more: Advantages and disadvantages of FKM vs EPDM for ‘O’ rings

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