The term “hydraulic seals” actually describes a class of seals that are
used in applications with either rotary or reciprocating motions.auto
oil seals Made in China. Hydraulic seals are exposed to hydraulic fluids
such as hydrocarbon and phosphate ester and are designed for
high-pressure dynamic applications such as hydraulic cylinders.
Hydraulic seals usually need to be higher friction seals than pneumatic
seals but often operate under lower operating speeds.
Rod seals, piston seals, u-cups, vee-cups and flange packings are just
some of the sealing designs that can be used as a hydraulic seal.
Sometimes a composite seals are used as hydraulic seals. A composite
seal is a product which has two or three materials manufactured into one
seal. Often there will be an elastomer ring and a PTFE ring giving the
seal the advantages of both materials.rubber seal
The sealing orientation for hydraulic seals can include internal (rod
seal), external (piston seal), symmetrical or axial seal. With the
internal (rod) seal, the seal is fit into a housing bore and the sealing
lip touches the shaft. With the external (piston) seal, the seal is
placed onto a shaft and the sealing lip touches the housing bore. Since
symmetric seals are the same on both sides they will function as either a
rod or a piston seal. The axial seal fits axially against the
housing.auto oil seals Made in China.
Rotary applications need only one hydraulic seal (single acting) because
it can seal in the one axial direction the application is moving.
However, a reciprocating application will need two hydraulic seals
(double acting),rubber seal. one for each of the directions.rubber sealing.
The life of hydraulic seals is dependent on many factors including the
maximum operating speed, maximum operating temperature, maximum
operating pressure and the vacuum rating. When ordering hydraulic seals
you will want to know the shaft outer diameter or seal inner diameter,
housing bore diameter or seal outer diameter, the axial cross section
and the radial cross section.
Potential problems come from:
Pressure If pressures become too high then extrusion can take place in
the gap between the cylinder and piston, or the gland and the rod. You
will want to have an elastomer that is resistant to extrusion in high
pressure conditions. Anti-extrusion rings and guide rings can be
utilized as part of the configuration to help the elastomer adhere to
the metal surfaces in high pressure conditions.oil sealing.
Temperature As the temperature increases the fluid viscosity will
decrease and the effect will be poor lubrication and an increase in the
damage done by friction. This reduces the life of hydraulic seals. It is
important to chose an elastomer that can withstand the temperature in
the application.
Friction When you have a rigid surface and a flexible material and they
are sliding back and forth against each other in the way they do in
hydraulic seals, the elastomer can be damaged by friction in a very
short amount of time. The design needs to take into account the nature
of the elastomer and smoothness of the surface finish of the rigid
material.
Speed Speed is another important consideration. Obviously, the higher
the speed the more potential damage to the seal.auto oil seals Made in
China.
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