Upon exposure to elevated temperatures, normally at levels greater than 200oC, vapors emanate from lubricants, and ignite due to the oil vapor’s reaction with air or any ignition source. The ‘flash’ or ignition, eventually dies in this scenario.
This temperature is referred to as Flash Point. While not directly related to a lubricant’s performance or quality, care must be given in selecting a lubricant whose temperature exposure is lower than Flash Point, as a matter of simple safety.
Fire Point on the other hand, refers to a (higher) temperature at which the ‘flash’ or ignition is sustained, and continues to burn.
Auto-ignition temperature is at a higher temperature than Flash and Fire-Points, wherein a lubricant will spontaneously combust even without any ignition source.
Mineral-based and Synthetic Lubricants are normally ‘safe’, unlike solvents and highly volatile mineral spirits, especially fluids with Flash Points at 40oC or lower. Special handling and storage procedures are required for such flammable materials.
In certain industries such as metal foundries or glass-making, where there is a risk of accidental contact between a process material (such as molten aluminum) and a leaked-lubricant, then the use of Fire-Resistant Hydraulic Fluids (FRHF) are recommended.