Hydraulic valve problems caused by oil oxidation products

Modern hydraulic systems are sophisticated with proportional valves and servo valves. As they are sensitive to oil contamination, contamination control is imperative. The conventional practices of contamination control have focused on particulate contaminants but have paid less attention to oil oxidation products. In order to protect sophisticated hydraulic components, fine pore filters have been used. As both oil and filter materials are dielectric, friction between them generates static electricity. Accumulated static electricity causes spark discharges and damages oils. Therefore hydraulic valve problems have not been solved yet, even though the conventional contamination control is implemented. This paper discusses the mechanism of hydraulic valve lock due to oil oxidation products and the synergy effects of oil oxidation products and particulate contaminants for valve failures and verifies that the findings of the experiment can explain the hydraulic valve problems in the fields.