3. Viscosity: The air compressor oil that has been tested to meet the quality standards is placed in a test tube, and is sealed with a cork and wax. Do not fill it.
Leave a space of about 5 mm. Put all the tested air compressor oil in another test tube. The size and oil content of the test tube should be the same as the previous test tube. Also seal with two corks and wax, and observe the bubbles. The rate of rise.
If the bubble rises faster than the standard air compressor oil, the viscosity of this oil is low. On the contrary, the viscosity is high.