O Ring Seal Material
O-ring mechanical seals come in many styles and shapes. The o ring seal material required depends on temperature, pressure, chemical, and other environmental factors. The o ring material selection such as EPDM, Nitrile, Buna-N, Viton, FFKM are the most common materials that we supply. Applications range from garden hose couplings to critical aerospace or chemical plant duties.
Common Elastomer Materials of O Ring Mechanical Seals
Buna-nitrile is the most common elastomer used in mechanical seals. Depending on the exact compound, Buna is good for moderate temperatures, from about -35 °F to about 250 °F. Buna's chemical resistance is narrow, and it is used mostly for water-based applications. Buna is the lowest cost elastomer used in mechanical seals.
Fluoroelastomers (Viton) offer the best all-around chemical resistance value for mechanical seal applications. Fluoroelastomers can be used at continuous temperatures up to 400 °F. There are some applications — such as steam — and some specific chemicals — such as organic acids and ketones — where EPDM or Kalrez® are specified. While much more expensive than Buna, Viton is still moderately priced.
Ethylene propylene (EPDM) offers outstanding performance in steam and hot water. There are also specific chemical applications where EPDM is the best choice. EPDM is recommended for use up to 300 °F. EPDM is often priced between Buna and Viton.
FFKM offers excellent resistance to chemicals and extreme temperatures. Special compounds can operate beyond 300°C. FFKM is resistant to most chemicals including inorganic acids, alkalines, ketones, esters, alcohols, fuels, and hot water. It is ideal for applications in aggressive chemical environments.
Our Standard FFKM compound has outstanding heat resistance with service temperatures of -10°C to 310°C. Sealcon can offer direct equivalents to Kalrez, Simrez, Perlast, Chemraz, grades.
Aflas is a specialty, non-conventional fluoroelastomer. A cousin of Viton, it offers higher heat resistance and performs well in high concentrations of acids, oxidants, and alkalis. Aflas is usually somewhat more expensive than Viton.
Kalrez is usually the most expensive elastomer option available. With specialty compounds available for use with nearly any chemical, and the ability to withstand temperatures up to 600 °F, Kalrez is an amazing elastomer. O-rings often cost hundreds of dollars each, so Kalrez is only used where absolutely necessary.
There are a variety of specialty elastomers on the market, most of which compete with one of the above materials. Sometimes these are specified by a seal or pump OEM, and Infinity Pump can source these materials for you.