Most of the construction machinery is constructed in the field far away from the oil testing laboratory. In the absence of special testing instruments, we have summarized several simple methods for testing and identifying the quality of hydraulic oil for equipment managers.
1. moisture content
(1) Visual inspection method. If the oil is milky white and cloudy, it means that the oil contains a lot of water.
(2) Combustion method. Dab a little of the oil to be tested on clean, dry cotton gauze or tissue paper, then set it on fire. If there is a "crackling" cracking sound or flashing phenomenon, it means that the oil contains more water.
2. Impurity content
(1) Direct identification. If there are obvious suspended metal particles in the oil, you will feel the existence of fine particles when you pinch them with your fingers; under the light, if there is a reflective flash point, it means that the hydraulic components have been seriously worn; if there are a lot of metal chips deposited at the bottom of the fuel tank , indicating that the main pump or motor has been severely worn.
(2) Filter paper detection. For hydraulic oil with higher viscosity, it can be diluted with pure gasoline and then filtered with clean filter paper. If a large amount of mechanical impurities (metal powder) are found on the filter paper, it means that the hydraulic components have been seriously worn.
(3) Sound and vibration judgment. If the entire hydraulic system has large and intermittent noise and vibration, and the main pump makes a "humming" sound, or even the phenomenon of piston crawling occurs, then observe the liquid level of the oil tank, the outlet of the oil pipe or the transparent liquid level gauge, and you will find that There is a lot of foam, which means that a lot of air has penetrated into the hydraulic oil.
(4) Heating detection. For hydraulic oil with lower viscosity, it can be directly put into a clean and dry test tube to heat up. If the oil in the test tube is found to be precipitated or suspended, it means that the oil already contains mechanical impurities.
 
3. viscosity
(1) Test tube inversion method. Put the tested hydraulic oil and standard oil in two transparent glass test tubes with the same inner diameter and length respectively (do not fill them too much), and plug the two test tubes with wooden stoppers. Place the two test tubes side by side, then quickly turn both tubes upside down at the same time. If the bubbles in the tested hydraulic oil test tube rise faster than the bubbles in the standard oil test tube, it means that the viscosity of the oil is lower than that of the standard oil; if the bubbles of the two types of oil rise at a similar speed, it means that their viscosity is also similar .
(2) The glass plate tilting method. When the machine has been used for a period of time, if the viscosity of the hydraulic oil does not meet the requirements and needs to be replaced with new oil, a clean glass plate can be taken, placed horizontally, and the hydraulic oil to be tested is dropped on the glass plate. Add another drop of standard hydraulic oil (new hydraulic oil of the same brand) next to it, then tilt the glass plate and observe it carefully. If the flow rate and flow distance of the tested oil are larger than those of the standard oil, it means that its viscosity is lower than that of the standard oil; otherwise, it means that its viscosity is higher than that of the standard oil.
4. Whether the oil has deteriorated
(1) Take out a little oil to be tested from the oil tank and filter it with filter paper. If there is black residue on the filter paper and a pungent odor, it means that the oil has been oxidized and deteriorated; you can also directly take out the part from the bottom of the oil tank Precipitate the sludge. If you find that there are many asphalt and colloidal deposits in it, put it on your fingers and pinch it. If you feel that there is a lot of colloid and strong adhesion, it means that the oil has been oxidized and deteriorated.
(2) Take out a little oil to be tested from the oil pump. If it is found to be milky white and turbid (sometimes like light yellow milk), and it is identified by the burning method, it is found that it contains a lot of water, and it feels that it has lost its viscosity by hand. , it means that the oil has been completely emulsified and deteriorated.