How To Select Sealing Components?

Sealing components are the most important devices for current and future machinery and industrial equipment. Sealing components have two main functions. One is to prevent the leakage of grease, water, and gases; the other is to protect against dust.

There are two main categories used for sealing components, dynamic and static. The difference between static and dynamic seals is as follows.

Dynamic seals

Oil seals for rotary and reciprocating applications.

Piston and cylinder lip seals for hydraulic and pneumatic equipment.

Static seals

O-rings: round in cross-section, for industrial equipment and general purpose (bracelets).

Quarter rings are X-shaped in cross-section, for high pressure and industrial equipment.

Bonded seals: rubber with metal between bolt and nut, for dust protection and increased locking force.

Gaskets: made of many different materials and used in engines and other equipment.

V-rings: similar in cross-section to the V-shape, used for high pressure in hydraulic and pneumatic equipment.

PYG-type End-Face Sealing Ring

How do I select a sealing element?

System pressure, sliding speed, temperature, media, surface roughness, and system tolerances are important parameters when selecting the type of sealing element.

Pressure

The first important characteristic of the system that should be looked at is the pressure, as the system working force is obtained from the cylinder bore and the system pressure. When calculating the system pressure, we recommend considering a shock pressure which is usually higher than the normal working pressure. Today, the demand for higher forces has led to an increase in system pressure in hydraulic systems. This is why there are new profiles and new engineering materials

JIANKE offers sealing solutions. The working pressures of the sealing elements can be seen in the product program.

Temperature

The medium and the working temperature are the two most important factors in the selection of materials for sealing elements. The ideal operating temperature for sealing elements and systems is 50°C, but application temperatures are often up to 100°C.

In dynamic applications, the sealing elements do come into direct contact with sliding surfaces, which is why they are subject to the heat generated by friction. The system temperature should be lower than the operating temperature.

Internal Expanding Sealing Components (Type NM)

For special applications where high temperatures are required, we recommend using sealing elements made of FKM and/or PTFE. For low temperatures, it is thought that the sealing element will become harder (glass transition) and will not do the required work, but in reality, depending on the medium, the sealing element can work at temperatures up to -40°C. The operating temperature of the sealing element can be found in the product program.

Speed

Depending on the material, design, and application of the sealing element, the speed of the cylinder can be up to 15 m/sec. Speed is one of the important characteristics defining oil film generation and friction.

The sliding speed of the sealing element can be seen in the product program.

Media

The minimum and maximum operating temperature of the sealing element varies depending on the medium used. Seal elements can be used with mineral oils (DIN 51524), non-flammable hydraulic fluids (VDMA 24317 or DIN 24320), atmosphere, water and different types of media.

The viscosity of the medium is one of the reasons for the wear of the sealing elements. Pressure and temperature change the viscosity of the medium. The viscosity of the medium increases with pressure. An increase in temperature reduces the viscosity of the medium (this change depends on the type of medium). When selecting the type of medium, the effect of operating pressure and temperature on viscosity should be studied.