Abstract: In view of oil contamination, the main reason cause faults of hydraulic system, and present development status that oil contamination mostly cannot be on-line monitored at home and abroad, constant power measurement based on silting method is proposed, namely, in the constant power situation, to obtain degree of oil contamination indirectly by measuring the differential pressure through some fixed volume oil. DC electromagnets of hydraulic valves are used as active force to propel piston rod of the purpose made cylinder to obtain differential pressure, special metal membrane filter as sensing element, operating platforms for monitor and control are developed, and design, debugging and experimentation for the oil contamination on-line monitor system are accomplished. The experimental results indicate that the system could produce corresponding ISO, NAS and SAE oil contamination classes, and had favorable man-machine interactive ability. Compared with the off-line test device, the system has credible precision and real-time performance, which can meet the demands of operation requirements of production field and has certain popularization value.

Key words: Oil contamination, On-line monitoring Membrane filter silting method Constant power measurement