Oil pollution and its impact on the hydraulic system

1. Types and sources of pollutants

 

There are various kinds of pollutants in the hydraulic system oil, the most important of which are solid particles, in addition to water, air and harmful chemicals. The main sources of pollutants are as follows:

 

a. Originally left in the system, such as metal cutting, sand and cleaning solvents during component processing and system assembly.

 

b. Invasion from the outside, such as through the tank breathing holes and hydraulic cylinder piston rod seals from the external environment into the various pollutants of the system, as well as the oil and maintenance process brought in pollutants.

 

c. Internally generated by the system, such as particulate matter generated by the wear and corrosion of components in the system, and harmful compounds produced by oxidative decomposition of the oil.

 

For water-based working media, such as oil-in-water emulsion microorganisms and their metabolites and the necessary conditions for reproduction.

 

2. Hazards of oil pollution

 

Oil contamination directly affects the operational reliability of the hydraulic system and the service life of the components. Domestic and foreign data show that about 70% of hydraulic system failures are caused by oil pollution.

 

The main hazards of oil pollution to the hydraulic system are as follows:

 

1) Contamination wear of components

 

Contaminants in the oil can cause various forms of wear. The solid particles enter the gap of the movement of the element, causing cutting wear or fatigue wear on the surface of the part. The impact of solid particles left at high speed on the surface of the part causes erosion wear.

 

The water in the oil drinks the oil oxidative deterioration products to corrode the components. In addition, the cavitation caused by the air in the hydraulic system oil, in addition, the cavitation caused by the air in the hydraulic system oil will cause the surface of the component to be ablated and destroyed.

 

2) Component blockage and clamping failure

 

The solid particles block the gap and the orifice of the hydraulic valve, causing the valve core to block and clamp, affecting the working performance of the valve, and even causing malfunction and causing system failure.

 

The viscous material produced by the oxidation of the oil and the microbial metabolites in the water-based working medium cause the valve core to stick and cause the filter element to become clogged.

 

3) Accelerate the deterioration of oil performance,

 

The water, air and heat in the oil are necessary for the oxidation of the oil, and the metal particles in the oil play an important catalytic role in the oxidation of the oil. The test results show that when the colloids in the oil village and the metal particles and water, the oxidation rate of the oil increases sharply, and the catalytic action of iron and copper increases the oxidation rate of the oil by 10 times and 30 times respectively.

 

In addition, the water and suspended bubbles in the oil significantly reduce the oil film strength between the moving pairs, resulting in a decrease in lubrication performance.