Selection and use of hydraulic oil note

Abstract: The hydraulic oil is a lubricating oil, used as the working medium in the hydraulic system. Combination of work experience with hydraulic oil, hydraulic oil described selection method, and proposed precautions in use, only peer- drawing and reference.

Keywords:: hydraulic oil; choice; use; Notes

According to statistics, there's all kinds of hydraulic system failure, 60% to 70% and related hydraulic oil, hydraulic oil in the hydraulic system is very important. Hydraulic oil is the use of fluid pressure to the hydraulic system of the hydraulic medium, in the hydraulic system plays an energy transfer system, lubrication, corrosion, rust, cooling and so on [1-2]. for hydraulic oil, it should first meet the hydraulic device and start the operating temperature of the liquid viscosity temperature requirements, as viscosity of the oil directly with the hydraulic action, transfer efficiency and delivery accuracy, but also requires oil viscosity-temperature performance and shear stability should be made to meet the different uses of the various needs. In addition, the hydraulic oil to the metal and seals on the hydraulic system materials have good compatibility and filterability; with corrosion resistance and wear resistance and anti-air entrainment and foaming tendencies; better thermal stability and oxidation stability; with use of emulsion breaking activity; for some special purpose, but also with the fire and no pollution to the environment (such as the readily biodegradable and non-toxic). hydraulic oil according to use and features are generally divided into mineral oil-based hydraulic oil, synthetic hydrocarbon hydraulic fluids, fire resistant hydraulic oil, hydraulic oil clean, bio- degradation of the hydraulic oil type [3-4].

1 hydraulic oil should meet the requirements of
In the selection of a number of hydraulic oil should meet the following requirements: First, good viscosity-temperature performance. In the use temperature range, the oil viscosity with temperature changes as small as possible. Second, with good lubricity. Oil in the prescribed within the film should have sufficient strength to avoid friction. Third, good chemical stability. oxidative deterioration of oil should be easy to prevent sediment and affect the normal work; prevent the oxidation of the oil becomes acidic, on the metal surface from corrosion. Fourth, the quality should be clean, free of all impurities, and a good anti-bubble. Fifth, higher flash point, lower freezing point.

2, hydraulic fluid selection
Choice of hydraulic oil first thing to consider is the viscosity of the oil problem, that according to the type of pump, the working temperature, the system first determine the speed and pressure for the viscosity range, and then select the appropriate hydraulic oil varieties. Reasonable choice of hydraulic oil, for extend the service life of hydraulic equipment to improve efficiency and avoid accidents are all kinds of hydraulic significance. hydraulic oil selection includes two aspects, namely, the viscosity of species selection and choice. According to the working environment and working conditions of hydraulic fluid selection variety in the selection of hydraulic equipment used hydraulic oil, from the working pressure, temperature, considering the work environment, and judgments.

2.1 working pressure
Mainly on the hydraulic oil that is anti-wear lubrication request. Pressure system, hydraulic pump hydraulic components, especially in a state of boundary lubrication friction, increasing the positive pressure, through high speed friction and wear conditions are harsh, you must select lubrication or wear resistance, excellent HM extreme pressure oil. by hydraulic system and pump working pressure of the hydraulic oil pressure <8 MPa with the L-HH, L-HL (vane pump is with the L-HM), pressure 8 ~ 16 MPa with L-HL, L-HM, L-HV, pressure> 16 MPa with L-HM, L-HV hydraulic oil. Hydraulic system working pressure is generally the largest of its main oil pump pressure rated or marked. mainly lubrication of the hydraulic fluid wear resistance demands. high-pressure hydraulic system, hydraulic pump components, especially in a state of boundary lubrication friction, increasing the positive pressure, through high speed friction and wear conditions are harsh, you must select lubrication the abrasion resistance, excellent HM extreme pressure oil. by hydraulic system and pump working pressure of the hydraulic oil pressure <8 MPa with the L-HH, L-HL (vane pump is with the L-HM), pressure of 8 to 16 MPa with the L-HL, L-HM, L-HV, pressure> 16 MPa with L-HM, L-HV hydraulic oil. Hydraulic system working pressure is generally the largest of its main oil pump pressure rated or marked. Links to free Paper Downloads http://www.hi138.com 2.2 Operating temperature
Means the hydraulic system hydraulic oil temperature at work, the main viscosity of hydraulic oil temperature and thermal stability of the request, the working temperature of -10 ~ 90 �� with the L-HH, L-HL, L-HM hydraulic oil, lower than -10 �� with L-HV, L-HS, temperature> 90 �� selection of high quality L-HM, L-HV, L-HS. ambient temperature and operating temperature of general relations: hydraulic equipment in the factory workshop, the normal higher temperature than the ambient temperature 15 ~ 25 ��; hydraulic equipment outdoors in temperate, high 25 ~ 38 ��; in the tropical sunlight outside, the high 40 ~ 50 ��.

2.3 Working environment
On the one hand consider the work environment of hydraulic equipment, indoor or outdoor, underground or in water, and whether the large temperature difference between summer and winter in cold regions, inland desert areas such as work environment; on the other hand, if the hydraulic system near the surface of a high temperature above 300 �� heat or a fire place, we should choose resistant hydraulic oil. selected by using the temperature and pressure resistant hydraulic oil: high-temperature heat source or open flame near 7 MPa less pressure, temperature <50 �� with L-HFAE, L-HFAS; pressure 7 ~ 14 MPa, temperature <60 �� with L-HFB, L-HFC; pressure of 7 ~ 14 MPa, temperature 50 ~ 80 �� with L-HFDR; pressure> 14 MPa, temperature 80 ~ 100 �� with the L-HFDR.

3 Note the use of hydraulic oil
In use, to prevent oil deterioration, should pay attention to the following matters: First, to maintain the hydraulic system clean and prevent water, other oils, dust and other impurities mixed with oil. Second, the oil tank surface should be to maintain a certain height, the normal work tank hydraulic oil temperature should not exceed the allowed range, generally no more than 70 ��, or regulation to be cool. Third, oil change, the hydraulic system piping must be thoroughly cleaned, new oil filter and then into the fuel to . Fourth, can not be used to replace the hydraulic oil waste lubricating oil, otherwise it will cause great harm. because the hydraulic system's main components are precision coupling, and its precision, high finish, such as the distributor slide valve and cover the hole with the gap only 0.006 ~ 0.120 mm, impurities in waste lubricating oil will accelerate the wear and increase leakage. waste oil will plug back in the dirt on the valve orifice.

The hole diameter to only 1.0 ~ 1.2 mm, causing the hydraulic system malfunction, but also so lax return valve and valve seat closed, hydraulic system does not work. Too much dirt the filter will plug the fuel tank, resulting in increased oil resistance and inhalation of air, resulting in intermittent oil flow, oil pump issue a "scream", the fuel tank excluding a large number of bubbles, the lift weakness. waste oil in the water, acid and alkali material makes oil emulsion, causing system disorders, and hydraulic oil corrosion of seal components. As of waste lubricating oil of low viscosity, lubrication and sealing performance greatly reduced, so that the leakage component severe wear increased, resulting in the system can not build pressure, reduced component life. hydraulic system great harm of waste lubricating oil, the absolute prohibition of the use . indeed used, should be let go as soon as possible all waste oil, diesel and oil with a clean mixture of cleaning the entire hydraulic system, and then add the required new hydraulic oil.

4 References
[1] Chen Qilong, Jun Yang. How to select and use hydraulic oil [J]. Brick, 2008 (4) :44-45.

[2] Li Yun-chiu. Construction machinery selection and use of hydraulic oil [J]. Agricultural use and maintenance, 2006 (5) :37-38.

[3] General, Department of. Of how to select and use hydraulic oil [J]. Construction Machinery Technology & Management, 2002,15 (6): 55.

[4] and the selection and use of hydraulic oil [J]. Automotive and accessories, 2000 (28) :32-33.

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