FLASH AND FIRE POINT:

Flash point can be defined as, the temperature at which the oils gives out enough vapours that ignite for a moment when a small flame is brought near it. 

SIGNIFICANCE OF FLASH AND FIRE POINT

1) A lubricating oil selected for a job should have a flash point which is reasonable above its working temperature. 

2) This ensures safety against fire hazards during the storage, transport and use of the lubricating oil. 

It is also used to identify and to detect the contaminants in the oil.

ACID VALUE:

Acid value is defined as the number of milligrams of KOH required neutralize free fatty acids present in one gram of oil. 

SIGNIFICANCE OF ACID VALUE

The determination of acid value can help us know the suitability of the lubricating oil. Higher the acid value, more the corrosion of machine surfaces, more wear and tear, more maintenance cost of machines. 

VISCOSITY AND VISCOSITY INDEX:

Viscosity can be defined as, the property by virtue of which a liquid or fluid offers resistance to its own flow. rate of change of viscosity with respect to temperature. 

SIGNIFICANCE OF VISCOSITY AND VISCOSITY INDEX:

1) A lubricating oil selected for a job should have viscosity index as high as possible. 

2) This helps in controlling wear and tear of machine parts. 

3) The also helps to decide the addition of blending agents to improve the property of lubricating oil.