Analysis on the deterioration of the hottest oil q

2022-07-27
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Cause analysis of oil quality deterioration

I. oxidation:

cause: generally, there are three factors such as temperature, air and pressure

II. Pollution: according to statistics, about 70% of hydraulic system failures, whether oil pump or oil motor, are caused by hydraulic oil pollution

1. type: this kind of fixture has a high cost

(1) solid particle pollution:

hazard: the valve is clamped; Increase leakage; The filter is blocked; Oil oxidation, etc

according to practice, 5~15 μ M solid is the easiest to make the valve clamp, 10~30 μ M particles will cause wear of power components. The oil distribution plate of axial piston pump is 10~15 μ M is the most sensitive to solid particles, and the radial pump and motor are sensitive to 15~25 μ M solid particles are the most sensitive, vane pump and motor are sensitive to 20~30 μ M is the most sensitive

(2) water pollution:

hazard: metal corrosion; Reduce lubrication; Formation of ice crystals; Cavitation; Oil oxidation, etc. The water absorption saturation of hydraulic oil is generally 200~300ppm. The higher the temperature, the better the water absorption

(3) air pollution:

hazard: action delay; Cavitation; Oil oxidation, etc

when the content in the air exceeds 2% at present, the oil begins to become turbid. (up to 8%~10%)

the amount of air dissolved in the hydraulic oil depends on the following factors: the type of hydraulic oil; working pressure; Operating temperature

2. expression method of pollution degree:

a. macroscopic overall expression method: weight level mg/l; Ppm by weight; Parts per million of volume ppm (volume); b. Microscopic dispersion representation: the particle concentration of the interval (the number of particles within a certain size in a unit volume of oil; 2. The number of particles within the interval of the correct device on the stable base or on the workbench); Cumulative particle concentration (the number of particles with a size greater than a certain value in a unit volume of oil)

3. pollution detection method:

judge the quality of hydraulic oil by appearance on site, judge the quality of oil by dripping oil on fine filter paper on site, identify the hydraulic oil test items on site, and the laboratory will conduct regular sampling and testing

4. reasonable replacement of hydraulic oil

(1) fixed cycle oil change method:

it is specified that the service time of hydraulic oil is half a year, or one year, or the method of replacing hydraulic oil after 1000~2000h of operation (the first oil change of the new system after 500h, and then 5000h). This method is widely used, but it is not very scientific

(2) on site identification and oil change method: determined according to the use of on-site oil products

(3) comprehensive analysis oil change method: take out the oil sample for experimental analysis to determine. This method conforms to the oil change principle

5. measures to prevent pollution:

(1) set dust-proof device at the moving interface of hydraulic components

(2) select appropriate hydraulic oil, strengthen the management of hydraulic oil, and filter it when refueling; In addition, the surrounding environment is clean

(3) air oil filter shall be set at the vent hole of the oil tank, and the oil level of the oil tank shall be controlled at 2/3 of the height of the oil tank

(4) clean the oil tank regularly, and use the external filtering device to regularly purify the oil

(5) regularly check the integrity of the heat exchanger

(6) select appropriate oil filter

(7) clean or replace the filter element regularly (500h)

(8) regularly (1~2 times a year) take samples to check the quality of hydraulic oil, and treat or change the oil as appropriate

(9) prevent the mixing of new and old oils or the mixing of oils of different brands

(10) new system or hydraulic system after overhaul shall be flushed; (it is better to use mineral oil with lower viscosity than the working fluid, or use its own hydraulic oil; the temperature of the flushing fluid is controlled at 30~40 ℃; the flushing fluid circulating pump is better to use an external pump or an auxiliary pump in the system, and the main pump and key components should be bypassed during flushing to prevent pollutants from entering; the flushing should be carried out until there is no obvious pollution on the fine oil filter in the system.)

(11) drain the residual water at the bottom of the oil tank regularly

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