Composition of sealing materials in hydraulic systems

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According to Mr. Li, a senior consultant at Yilan, the sealing materials used in hydraulic systems currently include the following types: nitrile rubber, fabric-reinforced rubber, fluororubber, polyurethane, and polyether polyurethane. The main differences lie in: 1. the friction coefficient of the material; 2. temperature resistance; 3. pressure resistance; 4. hydrolysis resistance. 　　Commonly available ones include nitrile rubber, fabric-reinforced rubber, fluororubber, polyurethane, and polyether polyurethane. The main differences lie in: 1. the friction coefficient of the material; 2. temperature resistance; 3. pressure resistance; 4. hydrolysis resistance. The friction coefficient of nitrile rubber and rubber reinforced with fabric is generally between 1.3 and 1.5; that of fluororubber is usually between 1.0 and 1.3. The friction coefficient of ordinary polyurethane is around 0.8, while that of high-performance polyether polyurethane ranges from 0.18 to 0.30. Among the materials mentioned above, polyether polyurethane has better pressure resistance; when used as a seal, it can withstand larger extrusion gaps in hydraulic cylinders. Moreover, ordinary polyurethanes are not resistant to hydrolysis, while polyether polyurethanes overcome this drawback of ordinary polyurethanes and can resist hydrolysis.