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  Sealing
Element (Rubber) |
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An oil seal normally
consists of three basic components : Sealing
Element, Metal Case, and
Spring. It is a widely used sealing
component. The function of a seal is to prevent the leakage
of medium along the moving parts. This is mainly achieved by
the sealing element. The materials normally used are Nitrile,
Acrylic, Silicone,
and Fluorinated Rubber. |
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Nitrile
Rubber (NBR) |
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| NBR
is most commonly used material. It has good heat resistance
properties, good resistance to oils, salt solutions, hydraulic
oils, and gasoline. Operation temperatures are recommended from
-40° to 120°C.
It also functions well under dry environment, but only for intermittent
periods. The disadvantage is poor chemical resistance. |
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Polyacrylate
Rubber (PA) |
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| Acrylic rubber has better heat
resistance than Nitrile. It is recommended for high surface
speed environment. The operation temperatures are recommended
from -20° to 150°C. It should not be used with water
or in temperature below -20°C. |
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Silicone
Rubber (SI) |
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| Silicone compounds operate effectively
in a broad temperature range of -50° to 180°C. It is
unsurpassed in its resistance to heat and low temperatures.
The high lubricant absorbency of silicone minimizes friction
and wear. It is usually used for crank shaft seals. Silicone
has poor hydrolysis resistance. It should not be used in oxidized
or hypoid oils. |
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Fluorinated
Rubber (VI) |
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| Fluorinated rubber is widely
known under the du Pont trade name of Viton R. It has the best
resistance to chemicals, and superior performance to high temperatures.
Though VITON provides so many good prospects, it has the highest
cost. |
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| Performances
of TTO oil seals |
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| Temp.
Range (°C) |
-40
to 120 |
-20
to 150 |
-50
to 180 |
-30
to 200 |
| Hardness
(Shore) |
70
/ 80 / 90 |
70
/ 80 |
75
/ 85 |
70
/ 80 |
| Wear
Resistance |
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| Costs |
msot
economical |
3rd
costly |
2nd
costly |
highest |
| P.S.
Temp. Range may be vary in different grade. |
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| Resistance
to Chemicals TTO oil seals |
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| Inorganic
acids |
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| Organic
acids |
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| Alkali
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| Salt |
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| Alcohol |
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| Esters |
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| Phenol |
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| Ketones |
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Appicable |
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Applicable
but must be ovserved |
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Applicable
in a limited of time |
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Not
Applicable |
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| RPM
and Surface Speed |
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The table shows you the
permissible surface speed and RPM for various sealing element materials
and shaft diameters. |
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