PhosLube – Base Oils Flash Point
The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source. At the flash point, the vapor may cease to burn when the source of ignition is removed. Every liquid has a vapor pressure. As temperatures increase, so do vapor pressures. In turn, this increases the concentration of vapor coming from the flammable liquid. Certain concentrations of vapor in the air are necessary to sustain combustion, but concentrations are different for each flammable liquid. The flash point of a flammable liquid is the lowest temperature at which there will be enough flammable vapor to ignite. Base oils flash point is governed by distillation temperatures and/or boiling ranges.
- Open Cup Flash Point: In open cup devices the sample is contained in an open cup which is heated, and at intervals a flame is brought over the surface. The measured flash point will vary with the height of the flame above the liquid surface, and at sufficient height the measured flash point temperature will coincide with the fire point.
Closed Cup Flash Point: With Closed Cup Flash Point the vapors above the liquid do not have equal temperature as that of the liquid. Closed cup testers normally give lower values for the flash point than open cup. They provide a better approximation to the temperature at which the vapor pressure reaches the lower flammable limit.