Why does the hydraulic seal seal deteriorate?

The formation of the sealing effect: the dynamic seal is divided into a non-contact seal and a contact seal. Non-contact seals are mainly various mechanical seals, such as: graphite packing rings, floating ring seals, etc.; rubber-plastic composite seals and rubber-plastic composite seals are contact seals, relying on the pre-compression force loaded in the sealed cavity, Block the leak path to obtain a sealing effect. Seals for hydraulic systems are mostly static seals (face seals), reciprocating seals (pistons, piston rod seals) and rotary seals.

Factors affecting the sealing effect: the choice of sealing structure and oil film formation, pressure, temperature, material compatibility, material, hardness, geometry, surface finish of the working surface contacted by the dynamic seal.

Compatibility of sealing material with hydraulic oil (liquid)

One of the sources of particulate contamination of hydraulic oil is debris or wear debris that is produced by the seal material that is not compatible with the hydraulic fluid. The seal is damaged by the swelling or the unbonded inorganic material and the filling reinforcing material are extracted, so that the seal is damaged and fails, and the oil is contaminated to cause the hydraulic oil to deteriorate and become invalid.

The vane pump is widely used in the hydraulic system. When the working pressure is greater than 6.9 MPa, the wear problem becomes prominent, so the anti-wear agent is used in the hydraulic oil; in order to adapt to the hydraulic system near the high-temperature heat source and the open flame, the anti-wear is used. Phosphate, water-glycol hydraulic fluid, oil-in-water and water-in-oil emulsions. As well as a variety of hydraulic oils (liquids) for various types of composite additives such as anti-oxidation and anti-rust applications. The reason for the swelling or extraction of the seal is that the various chemical elements and their concentrations contained in the hydraulic oil have different effects on different sealing materials according to the principle of similar compatibility, and are also resistant to the sealing material. performance.