Compatibility Analysis of Seal And Lubricant

Water-based liquids (emulsified oil, brake fluid, coolant)

Water-based lubricants are widely used in hydraulic systems, braking systems and cooling systems because of their environmental protection and low viscosity characteristics. However, the presence of water may lead to the hydrolysis, swelling or degradation of some sealing materials.

Emulsified oil: usually compatible with NBR, but may affect PU (polyurethane) seals

Brake fluid (DOT 3/4/5): Ethylene glycol based brake fluid (DOT 3/4) can severely damage NBR and EPDM seals should be used

Coolant: Long-term exposure may cause aging of silicone rubber. FKM seals resistant to chemical corrosion are recommended

3. How to optimize the selection of seals

(1) Select sealing materials according to lubricants

When selecting seals, it is necessary to select suitable sealing materials according to the specific type of lubricant. The following table summarizes the compatibility between different lubricants and sealing materials:

(2) Measures to prevent seal failure

laboratory test

Before actual use, the seal and lubricant were soaked to observe the volume change, hardness change and chemical degradation.

It is recommended to conduct ASTM D471 (liquid compatibility test of rubber) or ISO 1817 (tolerance test of rubber and liquid).

Optimize the sealing design

Choose materials with strong resistance to chemical corrosion, such as fluororubber (FKM), hydrogenated nitrile rubber (HNBR) and so on.

Special coating or surface treatment is used to enhance the oil resistance and aging resistance of the seal.

Regular inspection and replacement

Make a reasonable maintenance plan, check the aging of seals regularly, and avoid long-term lubricant effects leading to seal failure.