The lower point of explosion is the temperature of a combustible liquid where the concentration of saturated steam in air is equal to the lower explosion limit.
according to BG Chemie R 003 6/2000
The lower point of explosion permits a more exact definition of the explosion limits than the flash point. Due to the complex determination however it is only rarely measured in a direct manner.
Usually an estimation is made by the flash point. If the maximum processing temperature lies over the lower explosion point of the liquid, then explosive steam /air mixtures can develop. If liquids are distributed in droplets the possibility of combustible atmospheres has to taken into account at temperatures below the LEP.