Contaminants in hydraulic systems include solids, air, water, chemicals and microorganisms. The sources of pollutants mainly come from three aspects:
1) Inherent pollutants in the system, such as residual pollutants in the process of processing, assembly, packaging and storage of system components;
2) Internal pollutants are generated, such as the wear debris generated by the wear of system components, the rust and spalling in the pipeline and the particles generated by the oxidation and decomposition of oil;
3) External intrusions, such as pollutants brought through the breathing hole of the oil tank, the piston seal of the hydraulic cylinder and the process of oil supplement, etc.
Solid particles are the most common and the most harmful among all kinds of pollutants in hydraulic system. Among the hydraulic system failures caused by pollution, except 30 are caused by corrosion, and the remaining 70 are caused by mechanical wear on the surface of hydraulic components caused by the existence of solid particles. Solid particles not only accelerate the wear of hydraulic components, but also plug the clearance and orifice of components, so that the control components action failure and cause system failure.
Because of the great harmfulness of hydraulic system pollution, the new hydraulic system or the modified hydraulic system should be washed through the system to make the cleanliness of hydraulic media meet the requirements. The hydraulic equipment test station of Wuhan Iron and Steel Co., Ltd. needs to be relocated due to the water station project of cold rolling plant. After the relocation, the hydraulic pipe is reinstalled.
