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NITRILE ( NBR )
Most commonly used sealing material. The
content of acrylo-nitrile can be varied, which results in
different responses. Nitriles are recommended for continuous
operation at temperatures from –40 to +105 ºC When a compound
are developed to attain a low temperature limit of –45 ºC,
the fluid resistance is reduced. Conversely, when compounds
are developed for maximum fluid resistance, extreme low temperature
flexibility is sacrificed. Nitrile also works in dry running
applications but only for intermittent periods. Mixtures on
the base of these elastomers are stable against engine oils,
greases, fuels, industrial fluids.
POLYACRYLATE ( ACM )
Polyacrylate elastomers have good compatibility
with higher temperatures up to 150 ºC and even to 177 ºC with
some fluids. They are well suited for use with extreme pressure
(EP) lubricants and have higher resistance to oxidation and
ozone. They should not be used with water or in temperatures
below –30 ºC. Polyacrylates are not recommended for dry running
applications.
SILICONE ( MVQ )
Silicone seals can operate at temperatures
ranging from – 60 to 200 ºC . The high lubricant absorbency
of silicone minimize friction and wear. It has almost unlimited
ageing stability against air, oxygen and ozone. However it
has poor compatibility with oxidized oils, some extreme pressure
additives and abrasive contaminants. Silicone should not be
used in dry running applications.
FLUORO ( VITON® ) ( FPM
)
Viton will handle temperatures from –30 to
204ºC . They resist most special lubricants and chemicals
that can destroy nitrile, polyacrylates and silicones. This
premium material with its extreme resistance to abrasion and
high temperatures, provide superior performance and wear.
Viton works in dry running applications but only for intermittent
periods.
NITRILE , Hydrogenated
( HNBR )
These vulcanisates offer a unique combination
of heat resistance,oil resistance and resistance to a number
of aggressive chemicals. These seals can operate at temperatures
ranging from –40 to 150 ºC
TEFLON/PTFE
In comparison to standard elastomers PTFE
offers wider media resistance. With the addition of appropriate
fillers, PTFE has excellent mechanical properties, low friction
and wear resistance. Outstanding resistance to dry running
applications. Operating temperature range –200 to +260 ºC
ETYLENE-ACRYLATE ( AEM )
Etylene acrylate rubber is more heat
resistant than ACM and it has properties between those ACM
and FPM. Good resistance to paraffin base mineral oils with
additives, water and refrigerants. Temperature range for use
: - 40 ºC to + 150 ºC
NBR/PVC Blend
Blends of nitrile and
pvc combine the oil, chemical and ozone resistance of pvc
with the solvent resistance and elastic properties of nitrile
rubber. Operating temperatures range
–40 to +100 ºC.
Leather
Leather offers good mechanical and dry running
capabilities. However heat and chemical resistance is less
than nitrile rubber.It is satisfactory for applications where
temperatures are within –54 to +82 ºC Leather is usually special
production item and as a natural product, quality can be variable.
Felt
Felt seals are generally limited to dust
exclusion. They can sometimes be used to retain heavy lubricants
under less then severe conditions. Operating temperatures
range –54 to 93 ºC
Case Materials
Generally, case materials are formed from
SAE 1110 cold rolled steel. They are specially treated for
protection against corrosion during ordinary handling and
storage.
Seal cases can be manufactured in stainless steel ( SAE 304
) for corrosion resistance and extreme conditions.
Spring Materials.
Most spring supplied with ordinary seals
are hard-drawn steel wire. Seals can be furnished with SAE
302 stainless steel springs.
Bore-Lock
This sealent helps fill small imperfections
in the bore. It is resistant to most oils, greases, gasoline
and acids. The Bore-Lock coating is 0.02/0.07mm thick as measured
on the seal diameter.(specified seal OD does not include the
thickness of the Bore-Lock.)
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