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　　How to filter the NAS grade of hydraulic oil

　　1、 What is NAS cleanliness?

　　In the world, the pollution degree standards issued by NAS and ISO are mostly used. As the blood of hydraulic system and construction machinery, the particle concentration and contamination degree of hydraulic oil seriously affect the service life of hydraulic system and lubrication system.

　　Nas1638 standard limits the allowable contamination level of various hydraulic system fluids. At present, the level of oil contamination of the hydraulic system manufactured in foreign countries is controlled above nas7 at the beginning of use. When it is reduced to nas9 after use, the hydraulic system generally will not fail. When the level of pollution is reduced to nas10-11, the hydraulic system will occasionally fail. When the pollution level of oil drops below nas12 level, there will be frequent failures. At this time, the hydraulic oil must be circularly filtered.

　　Note: nas1638 is counted in sections with 5 size segments. Because the contamination degree of each size section of the actual oil can not be the same, the contamination degree of the tested oil sample is determined according to the Zui high level. This can cause a problem. For example, the pollution degree of 5-10 μ m measured may be level 4, the pollution degree of 15-25 μ m particles may be level 6, the pollution degree of 25-50 μ m particles may be level 5, and the pollution degree of 50-100 μ m particles may be level 8. At this time, the data is difficult to process, often making the concept unclear. If it is conservative, it will be judged as level 8 according to the regulations, and the system is considered dirty.

　　In fact, the new wear theory shows that only the particles with the same size as the moving clearance of the components can cause serious wear, that is to say, the particles with the size of 5-15 μ m do great harm to Zui, while the particles with the size of 50-100 μ M can not enter the moving clearance, which has little impact on the wear.

　　Therefore, most of the hydraulic and lubrication systems in production workshops or factories and mines that require strict requirements must be equipped with a set of precise oil filtration and purification equipment, so as to ensure that the oil can be effectively cleaned and filtered at any time, so as to ensure that the oil cleanliness continues to be within a qualified range for a long time and prevent the system from continuous failure due to particle wear.

　　2、 Necessity of hydraulic oil filtration:

　　The working performance of the hydraulic system depends on the selection, maintenance and management of the hydraulic oil to a great extent. If it can be used and maintained reasonably, the working performance and service life of the hydraulic oil equipment can be effectively improved. If it is not used carefully, the hydraulic oil is often polluted, which will make the hydraulic system unable to work normally. 80% of the faults of the hydraulic system are due to the contamination of the hydraulic oil Caused by dyeing

　　We know that hydraulic oil belongs to one kind of lubricating oil. The so-called lubrication is to add lubricant between two contact surfaces in relative motion, so as to form a lubricating film between two friction surfaces, separate the surfaces in direct contact, turn dry friction into internal friction between lubricant molecules, so as to reduce friction, reduce wear and prolong the service life of mechanical equipment. The function of lubricating oil is to:

　　1. Reduce friction: adding lubricant to the friction surface can reduce the friction coefficient, thus reducing the friction resistance and energy consumption.

　　2. Reduce wear: the lubricant can reduce the wear caused by abrasive wear, surface fatigue and adhesive wear between the friction surfaces.

　　3. Cooling effect: the lubricant can absorb heat, conduct heat and dissipate heat, so it can reduce the temperature rise caused by friction heat.

　　4. Antirust effect: the presence of lubricant on the friction surface can prevent corrosion caused by air, water drop, water vapor, corrosive gas, liquid, dust and oxide.

　　5. Power transmission: in many cases, the lubricant has the function of power transmission, such as hydraulic transmission.

　　6. Sealing function: the lubricant forms a seal on some exposed parts, which can prevent the invasion of moisture and impurities.

　　7. Shock absorption function: it can absorb shock energy when subjected to impact load, such as automobile shock absorber, etc.

　　8. Cleaning function: impurities can be removed through the circulation of lubricating oil and filtered out through filter.

　　Therefore, if there are impurities in the lubricating oil, it will affect its effect on reducing friction and wear of the machine, thus affecting the service life of the machine. If you can ensure that the hydraulic oil in the hydraulic system of the equipment you use reaches the required filtering accuracy, then reducing the fault will play a decisive role. Therefore, the maintenance of hydraulic oil and the selection of filtering equipment are particularly important

　　3、 Hydraulic oil filtration method:

　　The hydraulic oil can be filtered by the hydraulic oil vacuum filter. It can quickly remove water, gas, impurity and volatile matter (gasoline, diesel, kerosene, etc.) from oil. Improve the quality of oil, restore the viscosity, flash point and service performance of lubricating oil. Ensure the normal operation of hydraulic system, power system and lubrication system.