① Water into the oil, will make the hydraulic oil emulsification, become turbid state. If the demulsibility of the hydraulic oil itself is poor, even if it stands for a period of time, the water will not separate from the oil, and the oil will always be in a white state. This kind of white emulsified oil enters into the hydraulic system, which not only makes the hydraulic components rusty, but also reduces the lubrication performance of friction pairs, aggravates the wear of parts and reduces the efficiency of the system.

② The iron system metal in the hydraulic system is rusted by the water, and the rust peeled off by the gear pump flows in the pipes and hydraulic components of the hydraulic system, spreads and spreads, resulting in the internal rust of the whole system, producing more peeled rust and oxidation products, and even a lot of oil sludge. These water pollutants and oxidation products not only become the catalyst for further oxidation, but also lead to the blocking and jamming of hydraulic components, resulting in a series of faults such as abnormal action of hydraulic system, pipe blocking, cooler efficiency reduction, oil filter blocking, etc.

③ Rust is formed in the presence of iron, water and air (oxygen). In addition to metal corrosion, it also increases the acid value of the oil, produces peroxide, organic acid and other oxidation products, reduces the anti emulsification and anti foaming performance of the hydraulic oil, and causes the oil to oxidize and deteriorate.