Simple Identification of Excavator Hydraulic Oil Quality
Posted on 01/09/2017
In the absence of special testing instruments, we have summarized several methods for simple testing and identification of hydraulic oil quality.
1. Moisture content
(1) Visual inspection method. If the oil is milky white and turbid, it means that the oil contains a lot of water.
(2) Combustion method. Dip a small amount of the oil to be tested into clean, dry cotton gauze or tissue paper, and then ignite it with fire. If there is a "crackling" sound or a flash of light, 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 presence of fine particles when you pinch it with your fingers; if there are reflective flash points under the light, it means that the hydraulic components have been severely worn; if there are a lot of metal shavings deposited at the bottom of the 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 severely worn.
(3) Sound and vibration judgment. If the entire hydraulic system has large, intermittent noise and vibration, and the main pump makes a "buzzing" sound, or even the piston crawls, then observe the liquid level of the oil tank, the oil pipe outlet or the transparent liquid level gauge, you will find that There is a lot of foam. This shows that a large amount of air has invaded the hydraulic oil.
(4) Heating detection. For hydraulic oil with low viscosity, it can be directly placed into a clean, dry test tube and heated to increase the temperature. If sedimentation or suspended matter is found in the oil in the test tube, it means that the oil contains mechanical impurities.
3. viscosity
(1) Test tube inversion method. Put the hydraulic oil to be tested and the standard oil into two transparent glass test tubes with the same inner diameter and length (do not fill them too full), and plug the openings of the two test tubes with wooden plugs. Place two test tubes side by side and then quickly turn both test 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 the viscosity of the standard oil; if the bubbles of the two oils rise at a similar rate, it means that their viscosities are also similar. .
(2) Glass plate tilting method. After the machine has been used for a period of time, if the viscosity of the hydraulic oil does not meet the requirements and new oil needs to be replaced, you can take a clean glass plate, place it horizontally, and drop a drop of the tested hydraulic oil on the glass plate, while Add another drop of standard hydraulic oil (new hydraulic oil of the same brand) next to it, then tilt the glass plate and observe carefully. If the flow rate and flow distance of the measured oil are greater than that 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. Has the oil deteriorated
(1) Take out a small amount of the oil to be tested from the fuel tank and filter it with filter paper. If there is black residue on the filter paper and a pungent smell, it means that the oil has oxidized and deteriorated; you can also take out part of it directly from the bottom of the tank. Precipitated oil sludge. If you find a lot of asphalt and gum precipitates in it, put it on your fingers and pinch it. If you feel that there is a lot of gum and strong adhesion, it means that the oil has been oxidized and deteriorated.
(2) Take out a small amount of the oil to be tested from the oil pump. If it is found to be milky white and turbid (sometimes like light yellow milk), and when identified by the combustion method, it is found to contain a large amount of water and has lost its viscosity by hand. , it means that the oil has been completely emulsified and deteriorated.
