Main indicators of lubricants

General physical and chemical properties

Each type of lubricating grease has its common general physical and chemical properties to show the inherent quality of the product. For lubricants, these general physical and chemical properties are as follows:


(1) Density

Density is the simplest and most commonly used physical performance index for lubricants. The density of lubricating oil increases with the increase in the amount of carbon, oxygen, and sulfur in its composition. Therefore, under the same viscosity or the same relative molecular mass, the density of lubricating oils containing more aromatic hydrocarbons and more gums and asphaltenes The largest, with more cycloalkanes in the middle, and the smallest with more alkanes.


(2) Appearance (chromaticity)

The color of oil can often reflect its refinement and stability. For the base oil, the higher the degree of refinement, the cleaner the hydrocarbon oxides and sulfides are removed, and the lighter the color. However, even if the refining conditions are the same, the color and transparency of the base oil produced from different oil sources and base crude oils may be different.

For new finished lubricants, due to the use of additives, the color as an index to judge the degree of refining of the base oil has lost its original meaning


(3) Viscosity index

Viscosity index indicates the degree to which oil viscosity changes with temperature. The higher the viscosity index, the less the oil viscosity is affected by temperature, the better its viscosity-temperature performance, and vice versa


(4) Viscosity

Viscosity reflects the internal friction of oil, and is an indicator of oil and fluidity. Without any functional additives, the greater the viscosity, the higher the oil film strength, and the worse the fluidity.


(5) Flash point

The flash point is an indicator of the evaporation of oil. The lighter the oil fraction, the greater the evaporation and the lower its flash point. Conversely, the heavier the oil fraction, the less evaporative, and the higher its flash point. At the same time, the flash point is an indicator of the fire hazard of petroleum products. The hazard levels of oil products are classified according to their flash points. The flash point is below 45℃ as flammable products, and above 45℃ is flammable products. It is strictly forbidden to heat the oil to its flash point temperature during oil storage and transportation. In the case of the same viscosity, the higher the flash point, the better. Therefore, the user should choose according to the temperature and working conditions of the lubricant when choosing the lubricant. It is generally believed that the flash point is 20~30℃ higher than the operating temperature, and it can be used with peace of mind.

Post time: Dec-25-2020