O-Ring Material Selection

There’s no material we don’t have in stock or can readily source it. From Buna to PTFE (a generic compound of Teflon™, a trademark of The Chemours Company) to Kalrez™ (a registered trademark of Dupont), we have most materials in most sizes in stock. Chemical compatibility, temperature tolerances, and hardness all play a part in what material you need for your application. Mil Spec, FDA approved, Simriz or Chemraz (economical equivalents to Kalrez), Food grade and even metal and x-ray detectable, we can supply all your needs. Mil Spec, compounds are approved to nearly every military, aerospace, ASTM, SAE, automotive, petroleum industry and commercial specification.  The most widely used are the AMS, AS, AN, M, MS, MIL and NAS specifications.  Check the Chemical Compatibility and Temperature charts and other information under Technical Information to make sure you get the best material for your application.

• Buna (Nitrile) – Buna is the most widely used O-Ring elastomer compound.
• FKM, also known as Viton™,a registered trademark name of the Chemours Company, is Fluorocarbon, a brand of synthetic rubber and fluoropolymer elastomer.
• EPR (EPM) – This is short for Ethylene Propylene rubber, and is very closely related to EPDM (Ethylene Propylene Diene Monomer). They are functionally the same thing. EPR is often recommended for steam, water, and automotive brake fluids.
• Silicone – The term silicone covers a large group of materials in which vinyl-methyl-silicone (VMQ) is often the central ingredient. Silicones are excellent seal materials for extreme temperature in static applications. Silicone is also specified in applications involving ozone and UV radiation.  Most silicone material is in red or orange color.
• Kalrez® – Kalrez® is a DuPont trademark, resistant to over 1,800 different chemicals while offering the high temperature stability of Teflon. Temperature range for these compounds is usually -4°F to 615°F.
• Chemraz® – (Green Tweed trademark name) Chemraz® is the Green Tweed version of Kalrez. It is also a member of the perfluoroelastomer polymer family Simriz
• Simriz- This is typically a lesser cost alternative to both Kalrez and Chemraz.
• Highly Saturated Nitrile (HSN) - Highly Saturated Nitrile – Hydrogenation of nitrile rubber removes most of the residual unsaturation of the polymer to make it far less vulnerable to attack by heat, ozone, and oxygen.
• PTFE or (Teflon®) - PTFE is also known as Teflon® (by The Chemours Company). Teflon® was discovered in 1938. PTFE is a hard plastic that must be laid in place because it is not stretchable. PTFE maintains strength and toughness at low temperatures down to -250°F and is good in tempuratures up to 450°F.
• Neoprene – Neoprene is a commercial name for polymers comprised of chloroprene. Neoprene combines good resistance to weathering and petroleum-based lubricants, a wide temperature range, and exceptional economy.
• Urethane – Many polyurethane items are referred to as urethane. Urethane exhibits good wear resistance and is economical.
• Material Options – If your items aren’t on the list of other polymers listed, that doesn’t mean we can’t get them. If you need a special material, we can work with our suppliers to get the material you need.

You can find additional technical information related to this and other materials regarding chemical compatibility, resistance to abrasion, suitability for dynamic or static applications, temperature operating ranges, longevity, and other factors on our Technical Information pages.

Rubber Properties This chart provides a general description of rubber mechanicals properties to assist in making the optimal choice of materials for your application and working conditions. Rocket Seals has 60+ years of product, materials and applications experience and can provide expert advice about all of these factors to consider and properties.

Key: 1: Excellent 2: Good 3: Fair 4: Poor

Chart

Elastomer Buna-N (Nitrile) Butadiene, Styrene Butadiene Butyl Chloroprene (Neoprene®) Ethylene Propylene Fluorocarbon Viton® Fluorosilicone Hydrogenated Nitrile Natural Rubber/ Isoprene Polyacrylate Silicone Summary Nitrile has good mechanical properties and high wear resistance relative to other elastomers SBR is similar to natural rubber.  SBR is mostly used in tires and seals for non-mineral oil Butyl has a very low permeability rate, make it a great seal under vacuum.  Butyl also has good electrical, shock dampening properties Neoprene® exhibits good oil, ozone, weather, aging, refrigeration and chemical resistance.  It also has good mechanical properties over a wide temperature range Ethylene Propylene Copolymer has excellent resistance to phosphate ester fluids (Skydrol), brake fluids (glycol base), steam, weather and ozone Responds very well with resistance to ozone, high temperatures, oxygen, mineral oil, synthetic hydraulic fluids, fuels, aromatics and many organic solvents and chemicals. Has excellent resistance to petroleum oils and fuels.  Fluorosilicone has limited strength and abrasion resistance so it is generally recommended for static applications only HNBR has excellent abrasion, compression set, tensile and tear properties.  Unlike standard nitriles, HNBR resists ozone, sunlight and other atmospheric environments Natural Rubber/ Isoprene has excellent dynamic properties.  However, it does not do well with petroleum oils, sunlight and ozone Polyacrylate is used in application such as transmissions or anything where there is petroleum oils and high temperature.  Highly resistant to ozone and weathering Silicone exhibits great temperature range capabilities.  Silicones also have good resistance to ozone, weather and is also a good insulator.  However, it has low tensile, tear and wear resistance Economy (Cost) 1 1 3 2 1 3 4 4 2 3 3 Tensile Strength 1.5 1.5 2 2 1.5 1.5 3.5 1 1 3 4 Maximum Elongation(%) 600 600 800 600 600 300 600 340 700 600 800 Min Hardness (Shore A) 40 40 40 40 40 50 50 50 40 40 25 Max Hardness Short A 90 90 80 90 90 95 80 90 90 90 80 Resilience/ Rebound 2 2 4 1.5 2 2.5 2 - 1 3 2.5 Compression Set 1.5 1.5 2.5 2.5 1.5 1.5 1.5 1.5 2 3 1.5 Adhesion to Metals 1.5 1 2 1.5 2.5 2.5 2.5 1.5 1 2 2 Abrasion Resistance 2 1.5 2.5 2 1.5 2 4 1.5 1 2 4 Tear Resistance 2 2 2 2 1.5 2.5 4 2 1.5 2.5 4 Weather Resistance 3 3 1.5 1 1 1 1 2 .3.5 1 1 Ozone Resistance 4 4 1.5 1.5 1 1 1 2 4 1 1 Dynamic Properties 1.5 2.5 3 3 1.5 1.5 4 1.5 1 3 4 Electrical Properties 3 1 1 2 1 2 1 3 2 3 1 Water Swell Resistance 2 1.5 1.5 2.5 1 2 2.5 1 1 4 2 Steam Resistance 4 4 2 4 1 4 4 1 4 4 3.5 Flame Resistance 4 4 4 2 4 1 2 4 4 4 3 Gas Impermeability 1.5 2.5 1 1.5 2 1.5 4 2 3 1 4 Chemical Resistance 2.5 2.5 1 2.5 1 1 1 2.5 2.5 4 1.5 Acid Resistance 2.5 2.5 1.5 2.5 2 1 2.5 1 2.5 4 2.5 Alkali Resistance 2 2.5 1.5 1.5 1 2.5 - 1 1.5 4 1 Alcohols 1.5 1.5 1 1.5 1 2.5 2 1 2 4 1.5 Lubricating Oils (Petroleum) 1 4 4 2 4 1 1.5 1 4 1 3 Aliphatic Hydrocarbons 1.5 4 4 3 4 1 2.5 1.5 4 2.5 4 Aromatic Hydrocarbons 4 4 4 4 4 1 2.5 3.5 4 4 4 Halogenated Hydrocarbons 3.5 4 4 4 4 1 3.5 4 4 3.5 4 Phosphate Ester (Skydrol) 4 4 2 4 1 4 3.5 - 4 4 4

Polar Solvents

(Keytones) 4 4 2 4 1 4 4 4 2.5 4 4 Key: 1: Excellent 2: Good 3: Fair 4: Poor