Why should the Viscosity test need to confirm the temperature
1. Why does the viscosity test determine the temperature?
To detect the viscosity of a lubricating oil, we select a temperature at which the measurement is performed because the viscosity changes with temperature. The same lubricant, the viscosity measured at different temperatures is not the same. As the temperature rises, the lubricating oil becomes thinner and the viscosity decreases. When the temperature decreases, the viscosity of the oil increases and the oil thickens.
2, detect the viscosity, 40 degrees or 100 degrees?
At present, the lubricating oil is generally measured at 40°C or 100°C, specifically at 40°C or 100°C, depending on the circumstances, and it is not determined arbitrarily.
The measurement temperature of the viscosity is preferably close to the temperature at which the device is operated. In general, industrial lubricants are tested at 40°C because the operating temperature of industrial equipment is closer to this range.
In addition, changes in the viscosity of lubricating oils are relatively more pronounced at low temperatures. Therefore, if you want to detect viscosity changes caused by some abnormal factors, such as water in the lubricating oil, mixed with fuel, changes in viscosity due to oxidation, etc., at a low temperature of 40°C. Relatively easier to detect.
However, the operating temperature of some devices is relatively high. In order to make the detection temperature close to the use temperature, we should detect the viscosity at high temperatures. For example, in an automobile engine, the viscosity is generally measured at 100°C.
3, calculate the viscosity index of lubricating oil
Some devices may experience large temperature changes during operation. In this case, we need to measure a high temperature viscosity and a low temperature viscosity. For example, multi-grade oils are used in lubrication situations where the temperature changes are large. Multi-grade oils are measured at two temperatures, one at a high temperature and one at a low temperature. Through these two viscosities, we can calculate the viscosity index of the lubricating oil. The viscosity index of lubricating oil is a very important indicator for the large temperature changes during operation. The high viscosity index indicates that the viscosity of the lubricating oil is relatively stable during temperature changes.