UEL 7 : Upper explosive limit. The concentration of flammable gas, vapour or mist in standard air, above which an explosive gas atmosphere will not be formed
Ministry of Business, Innovation and Employment, Glossary of terms and acronyms, Wellington, New Zealand 2010. http://wwwsosh.govt.nz/resources/glossary-u.shtml, (Occupn Hlth and Sfty - Brit) {530}