Lower Explosive Limit (LEL) 1 : Means the minimum concentration of vapor in air below which propagation of a flame does not occur in the presence of an ignition source
US Department of Labor, Occupational Safety & Health Administration, Shipyard Employment eTools - Glossary, Washington, DC, USA 2012. http://www.osha.gov/SLTC/etools/shipyard/glossary. html, (Shipyard Employment - Amer) {562}