| |
Nomenclature |
Nitrile
(Buna N) |
Silicone |
Fluorocarbon
(Viton, Fluorel) |
Fluorosilicone |
Ethylene-
Propylene |
| ASTM D2000 Prefix |
BG, BK, CH |
FG, FE, GE |
HK |
FK |
CA |
| ASTM D1418 Designation |
NBR |
PVMO, VMO |
FKM |
FYMO |
EPDM, EPM |
| Properties |
| Compression set resistance |
Very Good |
Excellent |
Very Good |
Very Good |
Very Good |
| Continuous high temp. limit |
250°F, 121°C |
450°F, 232°C |
400°F, 204°C |
400°F, 204°C |
300°F, 149°C |
| Dyanmic service/abrasion resistance |
Excellent |
Poor |
Very Good |
Poor |
Very Good |
| Hardness range, "A" scale |
40-90 |
40-80 |
70-90C |
60-80 |
50-90 |
| Low temp. capability |
-40°F, -40°C |
-75°F, -59.5°C |
-20°F, -29°C |
-75°F, -59.5°C |
-70°F, -57°C |
| Relative o-ring cost |
Low |
Moderate |
Moderate/High |
High |
Low |
| Fluid Compatability Summary |
| Acid, inorganic |
Fair |
Good |
Excellent |
Good |
Good |
| Acid, organic |
Good |
Excellent |
Good |
Good |
Very Good |
| Aging (oxygen, ozone, weather) |
Fair/Poor |
Excellent |
Very Good |
Excellent |
Very Good |
| Air |
Fair |
Excellent |
Very Good |
Very Good |
Very Good |
| Alcohols |
Very Good |
Very Good |
Fair |
Very Good |
Excellent |
| Aldehydes |
Fair/Poor |
Good |
Poor |
Poor |
Very Good |
| Alkalis |
Fair/Good |
Very Good |
Good |
Good |
Excellent |
| Amines |
Poor |
Good |
Poor |
Poor |
Very Good |
| Animal oils |
Excellent |
Good |
Very Good |
Excellent |
Good |
| Esters, Alkyl Phosphate (Skydrol) |
Poor |
Good |
Poor |
Fair/Poor |
Excellent |
| Esters, Aryl Phosphate |
Fair/Poor |
Good |
Excellent |
Very Good |
Excellent |
| Esters, Silicate |
Good |
Poor |
Excellent |
Very Good |
Poor |
| Ethers |
Poor |
Poor |
Poor |
Fair |
Fair |
| Gasoline |
Poor |
Poor |
Good |
Good |
Poor |
| Hydrocarbon fuels, Aliphatic |
Excellent |
Fair |
Excellent |
Excellent |
Poor |
| Hydrocarbon fuels, Aromatic |
Good |
Poor |
Excellent |
Very Good |
Poor |
| Hydorcarbon fuels, Halogenated |
Fair/Poor |
Poor |
Excellent |
Very Good |
Poor |
| Hydrocarbon oils, High Aniline |
Excellent |
Very Good |
Excellent |
Excellent |
Poor |
| Hydrocarbon oils, Low Aniline |
Very Good |
Fair |
Excellent |
Very Good |
Poor |
| Impermeability to gases |
Good |
Poor |
Very Good |
Poor |
Good |
| Ketones |
Poor |
Poor |
Poor |
Fair/Poor |
Excellent |
| Silicone oils |
Excellent |
Good |
Excellent |
Excellent |
Excellent |
| Vegetable oils |
Excellent |
Excellent |
Excellent |
Excellent |
Good |
| Water/steam |
Good |
Fair |
Fair |
Fair |
Excellent |
| |
| Material |
Advantages |
Disadvantages |
Nitrile (Buna)(NBR)
Nitrile is the most widel used elastomer for general purpose sealing. Nitrile has
excellent resistance to petroleum products and is superior to most elastomers with
regard to compression set (cold flow), tear and abrasion resistance.
|
•Excellent general sealing characteristics
•Excellent resistance to petroleum oils and fluids
•Good cold water resistance
•Can service a wide variety of temps.
•Low Cost
|
•Poor weather resistance
•Poor resistance to ozone
•Moderate heat resistance
•Poor resistance to strong acids
|
Silicone Rubber (Si)
Silicone possesses excellent resistance to temperature extremes. Silicone's retention
of it's properties at extremely high temperatures is superior to other eleastic
materials.
|
•Excellent high/low temp resistance
•Excellent resistance to dry heat
•Excellent compression set (cold flow) resistance
|
•Poor physical strength
•Poor resistance to petroleum products
•Poor dynamic sealing
|
Fluorocarbon Rubber (Viton)(FKM)
Fluorocarbon rubber is recommended for seal use in aircraft, automobile and other
mechanical devices requiring maximum resistance to elevated temperature and to a
wide variety of function fluids.
|
•Excellent resistance to petroleum products
•Excellent resistance to organic acids
•Excellent high temp. resistance
•Good compression set resistance
|
•Moderately low temperature resistance
•High cost
|
Fluorosilicone (FSi)
Fluorosilicone combines the good high and low temperatures of silicone with basic
fuel and oil resistance. Its primary use is in high temperature fuel systems or
where the dry heat resistance of silicone is required.
|
•Good heat resistance
•Good resistance to petroleum products
•Good low temp. resistance
|
•Poor physical strength ans abrasion resistance
•High cost
|
Ethylene-Propylene (EP)
Ethylene-Propylene is very effective in break systems and for sealing hot water
and steam. Etylene-Propylene performs in a wide temperature range and is ver weather
resistant.
|
•Excellent weather resistance
•Good hig/low temp. resistance
•Good abrasion resistance
•Relatively low cost
•Good chemical resistance
|
•Poor resistance to petroleum products |