Why should the temperature be confirmed for lubricating oil viscosity test? Because to detect the viscosity of lubricating oil, we all choose a temperature and measure it at that temperature, because the viscosity will change with the change of temperature. The viscosity of the same lubricating oil measured at different temperatures is different. When the temperature increases, the lubricating oil becomes thinner and the viscosity decreases. When the temperature drops, the viscosity of the lubricating oil increases and the oil thickens.
Lubricating oil viscosity test, 40 degrees or 100 degrees
Now, the viscosity of lubricating oil is generally measured at 40 ℃ or 100 ℃. It depends on the specific situation and is not measured at will.
The measurement temperature of viscosity can be close to the operating temperature of the equipment. Generally speaking, the viscosity of industrial lubricating oil is tested at 40 ℃, because the working temperature of industrial equipment is close to this range.
In addition, the viscosity change of lubricating oil composite additives is relatively more obvious at low temperature. Therefore, if you want to detect the viscosity change caused by some abnormal factors, such as water inflow in lubricating oil, mixed fuel, viscosity change caused by oxidation, etc., it is relatively easier to detect at low temperature of 40 ℃.
However, the operating temperature of some equipment is relatively high. In order to make the detection temperature close to the application temperature, we should detect the viscosity at high temperature. For example, the viscosity of automobile engine is generally detected at 100 ℃.
Calculate the viscosity index of lubricating oil
Sometimes the equipment will experience large temperature changes during operation. In this case, a high-temperature viscosity and a low-temperature viscosity should be measured during measurement. Through these two viscosities, we can calculate the viscosity index of lubricating oil. When the temperature change during operation is relatively large, the viscosity index of lubricating oil is a very important goal. The higher the lubricating oil index, it means that the viscosity of lubricating oil is relatively more stable when the temperature changes.