First, the oil mixed with water 1. Oil in the water into the way (1) leaving the tank Gein alternating hot and cold water in the air condenses into water droplets falling in oil. (2) sealed cooler or heat exchanger damage or leakage of the water cooling pipe ruptured human oil. (3) Mifengbuyan piston rod through the dense humid air enters the system condense into water droplets. (4) oil and water with some people when exposed to moisture in the oil with water absorption of pro-cooperation with the water. 2. After the oil mixed with water hazards (1) oil mixed with a certain amount of moisture will make hydraulic oil emulsion was opaque state. If the hydraulic oil emulsification capacity of their own poor, still for some time, water and oil can not be separated, so that the total oil in opaque state. The whitish emulsion of oil into the hydraulic system itself, not only within the rust hydraulic components, while reducing its lubricating properties, so that part of the wear increased, the system efficiency. (2) within the hydraulic system after ferrous metals rust, peeling off the rust in the pipes and hydraulic components hydraulic system flow, spreading down the entire system will lead to internal corrosion, resulting in more flaking rust and oxides. (3) Water and oil will be the role of certain additives such as precipitation and colloidal pollutants, accelerating the deterioration of the oil. (4) Water and oil in the role of sulfur and chlorine produce sulfuric acid and hydrochloric acid, the components of the abrasive wear increased, but also accelerate the oxidative deterioration of oil, and even a lot of sludge. (5) The resultant water pollutants and oxidation, then become a catalyst for further oxidation, leading to blockage or stuck hydraulic components, causing failure of the hydraulic system operation, with tubing plug, cooler, reducing efficiency and filter clogging and a series of failure. (6) In addition, at low temperature, the hydrogel to form tiny ice particles, it tends to plug the gap control elements and dead mouth. Second, oil, oil mixed with a variety of foreign particles in the granular solid pollutants mainly exist. Some components of these impurities during processing and assembly residues, some hydraulic components generated in the process at work, some of the intrusion of impurities from the outside world, the harm is: 1. The oil in a variety of particle impurities will cause the pump and motor hazards. When the impurity particles into gear pump or gear motor gear end and both ends of the cover side, top and shell between the teeth, or when the impurity particles into vane pump or motor of the leaf blade and leaf slots, the rotor face, and with oil disk, the stator and the rotor (blades at the top), with or when the impurity particles into the plunger piston motor piston or cylinder bore and piston, rotor and oil pan, and tilt plate slipper, variable body vice between the sliding, the fault may be that stuck. Stuck fault, if not caused, but also will wear increased. Impurity particles may also plug the pump into the oil before the oil filter, so that the pump causing cavitation, or multiple concurrent failures. 2. Oil hydraulic cylinders of various particles of impurities will cause harm. Particulate impurities cause the piston and the cylinder, piston rod and cylinder bore and sealing components to strain and wear, so that outflow increases, volumetric efficiency and effective thrust (pull) to reduce, if the particle impurities stuck piston or piston rod will result in fuel tank does not work. 3. Oil pollution particles in the various valve components will cause harm. Pollution particles may cause the slide valve 121, throttle stuck or blocked, resulting in failure of the valve action, even if the card does not produce death or blockage of failure, pollution particles also make valve components deputy campaign premature wear, with the gap increased, performance deteriorated. 4. Pollutants growth of bacteria, exacerbating oil aging, smelly black oil, and further pollution. This vicious cycle may have the following consequences: (1) plug the oil filter pollutants, resulting in pump suction air, vibration and noise. (2) pollutants increased friction cylinder or motor, resulting in crawling. (3) contamination of the servo valve, poor anti-pollution components complete loss of function. (4) gauge channel blocking contaminants, so the pressure is not correct transmission and response. Third, the oil penetrated the air in the air mainly from the oil loose fittings, joints do not close the device, exposed to oil seal failure surface of the tubing and place, the oil will be exposed to the atmosphere were dissolved air. In addition, when the fuel tank less, the speed of the hydraulic oil in the circulation, overcome all difficulties and bubbles, while oil pump suction pipe "eat oil" deep enough so that air can easily enter. Mixed with the hydraulic system of air, usually in a diameter of 0.05 ~ 0.50mm state of suspended air bubbles in the hydraulic oil, hydraulic oil within the hydraulic system, the bulk modulus and viscosity of hydraulic oil have a serious impact, with the hydraulic system pressure higher melting one part of hydraulic oil mixed with air, the remaining gas still exists. When mixed with the air volume increases, the volume of hydraulic fluid elasticity sharp decline in the hydraulic oil pressure wave propagation speed slows down, the oil viscosity increased linearly. Suspended in oil in a combination of air and hydraulic oil into the mixture, which depends on the stability of the oil bubble size, the hydraulic systems have a significant impact, possible vibration, noise, pressure fluctuations, hydraulic components do not stability, moving parts have to crawl to the impact of change, positioning or movement disorder, etc. are not allowed to failure, but also to increased power, accelerated oil oxidation and oil lubrication performance. (This article reproduced from http://www.dgybl.com)