2. Moisture: Put the air compressor oil into the test tube and observe its transparency. If it is not clear and transparent, but it is cloudy, it can be judged that the air compressor oil contains water. There are two reliable ways to determine if there is water in the oil.
Anhydrous copper sulfate (white powder) was placed in a test tube containing air compressor oil, such as copper sulfate from white to blue, indicating the presence of moisture in the oil. This method does not give the amount of water content, and can only be estimated based on the amount of bubbling of the air compressor oil during heating and the amount of copper sulfate added.
Pour the oil to be tested into a test tube, the amount of oil is two-thirds of the volume of the test tube. After sealing the test tube with a cork and wax, it was heated on an alcohol lamp. If there is a bubble, it will make a sound at the same time, and there will be condensation on the wall of the test tube above the oil surface, indicating that there is moisture in the oil.