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How To Choose Hydraulic Oil Seal

31 Jul.,2025

How To Choose Hydraulic Oil Seal?High - quality oil seals have better sealing performance, wear resistance and service life. When selecting, it is necessary to check the quality of the oil seal, including the smoothness of the surface, the uniformity of the material, and whether there are defects such as cracks and bubbles.

When selecting a hydraulic oil seal, the following aspects need to be considered:

Working conditions

- Pressure: The pressure resistance of the oil seal should match the maximum working pressure of the hydraulic system. For low - pressure systems (below 10MPa), general - purpose oil seals can be used; for medium - pressure systems (10 - 20MPa), oil seals with better pressure resistance are required; for high - pressure systems (above 20MPa), high - pressure - resistant oil seals must be selected to avoid oil leakage.

- Temperature: The working temperature of the hydraulic system has a great influence on the performance of the oil seal. The oil seal material should be able to maintain good elasticity and sealing performance within the working temperature range of the system. For example, in high - temperature environments, fluororubber oil seals can be used, which can withstand temperatures of up to 200°C; in low - temperature environments, silicone rubber oil seals have better low - temperature flexibility and can work normally at - 50°C or lower.

- Speed: The running speed of the hydraulic cylinder piston rod or rotating shaft also affects the selection of oil seals. At high speeds, the oil seal is prone to wear and heat generation, so oil seals with low friction and good heat - dissipation performance should be selected. For example, polyurethane oil seals have good wear resistance and low friction, and are suitable for high - speed occasions.

Seal type

- Radial oil seal: It is mainly used to seal the rotating shaft, such as the input shaft and output shaft of the hydraulic pump and motor. The structure of the radial oil seal is relatively simple, and it has good sealing performance for preventing oil leakage along the shaft.
- Axial oil seal: It is usually used to seal the piston and cylinder in the hydraulic cylinder to prevent oil from leaking between the piston and the cylinder wall. The axial oil seal can bear higher pressure and has better sealing performance in the axial direction.

Seal material

- Nitrile rubber: It has good oil resistance, wear resistance and low - temperature performance, and is suitable for general - purpose hydraulic systems. The working temperature range is generally - 40°C - 120°C.
- Fluororubber: It has excellent oil resistance, high - temperature resistance and chemical stability, and is suitable for high - temperature and high - pressure hydraulic systems. The working temperature can reach 200°C or higher.
- Polyurethane: It has good wear resistance, tear resistance and high - pressure resistance, and is suitable for hydraulic systems with high - speed and high - pressure requirements. The working temperature range is generally - 30°C - 80°C.

Size And Fit

-Inner diameter and outer diameter: The inner diameter of the oil seal should match the diameter of the shaft or piston rod, and the outer diameter should match the size of the installation hole. The tolerance range of the size should be strictly controlled to ensure a good fit between the oil seal and the shaft or hole.
-Width: The width of the oil seal should be selected according to the installation space and the pressure - bearing requirements of the hydraulic system. Generally speaking, the wider the oil seal, the better the pressure - bearing capacity, but it also needs to be coordinated with the installation space.

Quality And Brand

-Quality: High - quality oil seals have better sealing performance, wear resistance and service life. When selecting, it is necessary to check the quality of the oil seal, including the smoothness of the surface, the uniformity of the material, and whether there are defects such as cracks and bubbles.
-Brand: Choose well - known brands and reliable manufacturers, because their products usually have better quality and after - sales service. Well - known brands have more experience and technical advantages in the production of oil seals, and can provide more stable and reliable products.

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