O-ring application guide
Nitrile Rubber
Nitrile Rubber also known as Acrylonitrile-Butadiene (NBR) and Buna N. The acrylonitrile content varies between 18 and 50% and influences the physical properties of the finished product. A higher Nitrile content enhances resistance to fuel and oil but elasticity and resistance to compression set is adversely affected
Operating Temperature Range
Heat Resistance – up to 100°C
Cold Flexibility – between -34°C and -57°C depending on the compound
OK
Aliphatic Hydrocarbons (propane, butane, petroleum oil, mineral oils and greases, diesel fuel and fuel oil); Dilute acid, alkali and salt solutions at ambient temperatures; water up to 100°C with the right compound
Not Recommended
Fuels with a high aromatic content; aromatic hydrocarbons (benzene); Chlorinated hydrocarbons (Trichlorethylene); Polar solvents (ketone, acetone, acetic acid, ethylene ester); strong acids; glycol-based brake fluids; ozone, atmospheric weathering
Hydrogenated Nitrile Rubber
Hydrogenated Nitrile Rubber also known as Highly Saturated Nitrile Rubber (HNBR). It is achieved by hydrogenated NBR. Greatly improved wear and extrusion resistance over standard NBR. Good chemical compatibility and can be used with oils which have aggressive additives. Has an extended high temperature range.
Operating Temperature Range
Heat Resistance – up to 150°C
Cold Flexibility – down to -35°C
OK
Mineral oil-based hydraulic fluids, animal and vegetable fats, diesel fuel, ozone, sour gas, dilute acids and bases.
Not Recommended
Ketones, Ethers, Organic acids.
Neoprene
Neoprene also known as Chloroprene Rubber. Chloroprene was the first synthetic rubber developed commercially and exhibits generally good resistance to chemicals, ozone and weathering. Its main use is to seal refrigerants.
Operating Temperature Range
Heat Resistance – up to 120°C
Cold Flexibility – down to approximately -40°C
OK
Water at low temperatures; refrigerants; ammonia; carbon dioxide; improved ozone, weathering and ageing resistance compared with Nitrile
Not Recommended
Aromatic hydrocarbons (benzene); chlorinated hydrocarbons (trichlorethylene); polar solvents (ketones, esters, ethers, acetone)
Hypalon®
Hypalon® is a DuPont™ trade name for Chlorosulfonated polyethylene rubber. Has good Ozone resistance, colour stability, chemical resistance, wear and abrasion resistance and high impact resistance.
Operating Temperature Range
Heat Resistance – up to 121°C
Cold Flexibility – down to -25°C
OK
Ozone, hydrocarbon oils and fuel exposure, sodium hypochlorite, sodium peroxide, ferric chloride, sulphuric acid, chromic acid, hydrofluoric acid, salt solutions, alcohols, alkalies and water.
Not Recommended
Aliphatic, aromatic, chlorinated hydrocarbons, aldehydes and ketones.
Ethylene Propylene Rubber (EPDM)
Ethylene Propylene Rubber (EPDM) has broad support due to its resistance to phosphate ester type hydraulic fluids.
Operating Temperature Range
Heat Resistance – up to 149°C
Cold Flexibility – down to -40°C
OK
Phosphate ester based hydraulic fluids; water and steam to 204°C; dilute acids and alkalies; ketones; alcohol; automotive brake fluids
Not Recommended
Petroleum oils; di-ester based lubricants
Silicone Rubber
Silicone Rubber covers a group of compounds that has vinyl-methyl-silicone (VMQ) as the main ingredient. Silicone elastomers have relatively low tensile strength and poor tear and abrasion resistance. However they exhibit good heat and weathering resistance as well as good insulating and physiologically neutral properties.
Operating Temperature Range
Heat Resistance – up to 200°C
Cold Flexibility – down to -55°C
OK
Hot air; engine and transmission oils; animal and vegetable oils and greases; brake fluid; fire-resistant hydraulic fluids; moderate water resistance
Not Recommended
Superheated water/steam; acids and alkalies aromatic mineral oils; hydrocarbon based fuels; aromatic hydrocarbons
Fluorosilicone rubber (FVMQ)
Fluorosilicone rubber (FVMQ) is generally used for static seals only due to poor dynamic qualities. Excellent low temperature resistance. Commonly used in aviation nose cones and door seals.
Operating Temperature Range
Heat Resistance – up to 230°C
Cold Flexibility – down to -60°C
OK
Dilute acids, alcohols, dilute alkalies, animal & vegetable oils, diester oils, some esters, fuel, halogenated solvents, LP Gases & Fuel oils, mineral oils, refrigerant ammonia, silicone oil, solvent resistance, ozone, flame resistant, radiation, sunlight, water and weather resistant.
Not Recommended
Abrasion resistance, tear resistance, aldehydes, amines, brake fluids, some esters, ketones, solvents.
Fluorocarbon (FKM/FPM)
Fluorocarbon (FKM/FPM) commonly known by its DuPont™ trade name, Viton®. These materials are noted for their high resistance to temperatures and chemicals. They have excellent resistance to ageing and ozone and very low gas permeability that makes them suited to vacuum applications.
Operating Temperature Range
Heat Resistance – up to 200°C
Cold Flexibility – down to approximately -40°C
OK
Mineral oil and greases (low swelling in standard oil tests); silicon, mineral and vegetable oils and greases; aliphatic hydrocarbons (propane, butane natural gas); aromatic hydrocarbons (benzene, toluene); chlorinated hydrocarbons (carbon tetrachloride, trichlorethylene); fuels incl high methanol content; high vacuum work
Not Recommended
Glycol based brake fluids; ammonia gas; amines and alkalies; superheated steam; low molecular weight organic acids (eg formic, acetic)
Viton® Extreme™
Operating Temperature Range
Heat Resistance – up to 200°C
There are several different compounds available to suit most applications, please contact Fluid Seals for further information on the right compound for your application.
Aflas®
Aflas® (Tetrafluoroethelene propylene – TFE/P) Aflas® is Asahi Glass Co. trade name for a non-conventional fluoroelastomer (FKM) material which has a different chemical structure than other FKM’s. It has significant advantages over FKM’s, Aflas® exhibits excellent heat resistance; 3 months @ 230°C, 30 days @ 260°C and intermittent tolerance @ +300°C.
Operating Temperature Range
Heat Resistance – up to 300°C
Cold Flexibility – down to 0°C
OK
Oils and lubricants, hydraulic fluids, brake fluids, transmission fluids, power steering fluids, sour oil and gas, amine corrosion inhibitors, ozone and weathering, solvents, steam and hot water, acids, bases, oxidizing agents, bleaches, pulp and paper liquors, insecticides, herbicides, gamma radiation and alcohols.
Not Recommended
High aromatic fluids (Toluene), non-polar solvents, ethers, ketones, some chlorinated solvents, organic acetates, most Freon’s and acetic acid.sdfsdf
Perfluoroelastomer (FFKM)
Perfluoroelastomer (FFKM) exhibit the best heat and chemical resistance of all elastomers. Common brands are Kalrez®, Chemraz®, Isolast® and Perlast®.
Operating Temperature Range
Heat Resistance – up to 327°C
There are several different compounds available to suit most applications, please contact Fluid Seals for further information on any of these compounds.
Other materials used for O-rings
Other materials used for O-rings include, PTFE (universally noted for its chemical resistance but difficult to install due to minimal elasticity); FEP encapsulated (FEP is similar to PTFE and is used to cover Viton® or silicone O-rings to offer the chemical inertness of PTFE with some elasticity)