The lower limit of flammability of a gas or vapour at normal ambient temperatures expressed as percentage of the gas or vapour in air by volume. This limit is assumed constant for temperatures up to 1300C
The International Occupational Safety and Health Information Centre, Glossary of Terms On Chemical Safety, World Health Organization (WHO), The International Programme on Chemical Safety IPCS: Division of Environmental Health (A joint venture of the United Nations Environment Programme UNEP, the International Labour Organisation ILO, and the World Health Organization WHO), Geneva, Switzerland 2012. http://www.ilo.org/legacy/english/protection/safew ork/cis/products/safetytm/glossary.ht,(ChemSfty - Brit) {479}