how an o-ring functions
\ physical
properties of o-ring compounds \ types of seals \ general design and gland
dimensions \ standard
o-ring sizes and dimensions \ compound
information
Basic
O-Ring Elastomers and their Characteristics
AFLAS* (TFE Propylene)
Trade Name:
*Above...............................................................................3M
This
recently introduced material is unique due to its resistance to petroleum
products, steam, phosphate esters and brake fluids. In some respects, it
exhibits media compatibility properties similar to ethylene propylene and
fluorocarbon. It has fair resistance to brake-fluids and phosphate esters while
exhibiting good resistance to petroleum oils. This material is finding interest
for seal applications requiring petroleum resistance, steam and ammine
resistance such as those applications encountered in the petroleum industry.
Additional interest is being generated in applications requiring petroleum and
brake fluid resistance or petroleum and phosphate ester resistance. The
temperature service range for this material is -20°F to +400°F.
Applications:
Petroleum fluids & steam
Petroleum fluids & ammines
Petroleum fluids & brake fluids
Petroleum fluids & phosphate ester
ETHYLENE PROPYLENE (EPM, EPDM)
(Ethylene Propylene Copolymer)
Trade Names:
Nordel . . . . . . . . . . . . . DuPont Dow
Vistalon . . . . . . . . . . . . Exxon Chemical
Epsyn . . . . . . . . . . . . . .Copolymer Rubber
Royalene . . . . . . . . . . . Uniroyal
This
material was introduced in 1961 and found broad acceptance in application
requiring excellent resistance to Skydrol and other phosphate ester fluids at
higher temperatures. In addition, compounds of this material exhibit excellent
resistance to automotive brake fluids and steam.
The
temperature service range for these compounds is -65°F to +300°F.
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Applications: Automotive Brake Fluids |
FLUOROCARBON (FKM)
(Vinylidene fluoride-hexafluoropropylene)
Trade Names:
Fluorel . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3M
Viton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DuPont-Dow
Compounds of these polymers exhibit
excellent resistance to petroleum products, low compression set and high
temperature resistance. The low temperature capability is somewhat restricted,
however, in some case the flow temperature sealing capability may be increased
by specific design parameters. These materials meet the stringent requirements
of Military Specifications Mil-R83248 and Aerospace Specifications AMS 7278,
AMS 7279, and AMS 7280. They are especially good for hard vacuum service and
low gas permeability. The normal temperature service range in fluorocarbon is
-20°F to +400°F / + 450°F.
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Media Compatibility |
Non-Compatible: |
FLUOROSILICONE (FVMQ)
Trade Names:
LS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dow
FSE . . . . . . . . . . . . . . . . . . . . . . . . . . .
.GE
These polymers exhibit good low/high
temperature resistance with excellent resistance to petroleum oils and fuels.
They are used in aerospace applications for fuel systems and systems requiring
resistance to diester base lubricants to 350°F. Due to the limited strength and
abrasion resistance of these materials, they are generally recommended for
static applications only. The sealing temperature service range is -80°F to
+350/400°F.
|
Applications |
Non-Compatible |
NEOPRENE (CR) CHLOROPRENE
Trade Names:
Bayprene . . . . . . . . . . . . . Mobay
Butchlor . . . . . . . . . . . . . . . Ditsugil
This was the earliest of the volume American
synthetic rubbers. Compounds from neoprene exhibit fair oil resistance, good
ozone and weather resistance. Due to the excellent resistance to refrigerants
such as Freon, neoprene compounds are used in refrigeration systems. The
sealing temperature service range for these compounds is -65°F to +250/300°F.
|
Applications |
Non-Compatible |
NITRILE (NBR or Buna N)
(Acrylonitrile-Butadiene Copolymers)
Trade Names:
Chemigum . . . . . . . . . . . . . . Goodyear
Hycar . . . . . . . . . . . . . . . . . .Zeon Chemical
Krynac . . . . . . . . . . . . . . . . .Polysar
Ny Syn . . . . . . . . . . . . . . . . .Copolymer
Paracril . . . . . . . . . . . . . . . . .Uniroyal
Perbunan . . . . . . . . . . . . . . . Mobay
Compounds of these polymers are the backbone
of the O-Ring line. Polymers vary from 18 percent to 50 percent acrylonitrile
content. Resistance to petroleum products increases as acrylonitrile increases;
conversely, low temperature flexibility decreases. Government specifications
require low acrylonitrile.
Nitrile Compounds can exhibit excellent
compression set, tear and abrasion resistance. Unless especially compounded,
they do not have good resistance to ozone, sunlight, or weather. They should
not be stored near motors or other ozone generating electrical equipment. They
should be kept from direct sunlight. Compounds from nitrile rubber can exhibit
a temperature range of -65°F to +300°F, although no one formulation may exhibit
the total range.
|
Media Compatibility |
Non-Compatible |
HIGHLY SATURATED NITRILE (HSN)
Trade Names:
Therban . . . . . . . . . . . . . . Mobay
Zetpol . . . . . . . . . . . . . . . Zeon Chemical
Tornac . . . . . . . . . . . . . . Polysar
This material is a highly saturated nitrile.
Therban exhibits excellent abrasion,
compression set, tensile, and tear properties. Unlike standard nitriles, it
exhibits resistance to ozone, sunlight, and other atmospheric conditions. This material
also exhibits vastly improved resistance to heat aging in the 300°F range and,
for short periods, up to 350°F. Presently available material exhibits a low
temperature range to -40°F.
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Applications |
Non-Compatible |
SILICONE (VMQ)
Trade Names:
Silastic . . . . . . . . . . . . . . .Dow
None . . . . . . . . . . . . . . . .General Electric
None . . . . . . . . . . . . . . . .Stauffer-Wacker
None . . . . . . . . . . . . . . . . Union Carbide
Silicones are noted for their excellent heat
resistance, and are utilized in applications which expose seals to high
temperature dry heat. They are not recommended for dynamic applications due to
their relatively poor tensile and tear strength. They exhibit the best low
temperature flexibility of all elastomers and can be used in static
applications to -150°F. Silicones should be considered to be non-petroleum
resistant, but can be used in specific high aniline point petroleum oils. The
temperature service range for silicone compounds is -80°F to 450°F (All
silicone formulations do not exhibit the capability of this entire range).
|
Applications |
Non-Compatible |