Â· 43 comments. in Facts. An intelligence quotient, or IQ, is a score derived from one of several standardized tests designed to assess intelligence. The abbreviation âIQâ comes from the German term Intelligenz-Quotient, originally coined by psychologist William Stern.
Lower explosive limit. Lower explosive limit (LEL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower flammable limit (LFL).
Below this it can be deemed as too lean to burn. So what does that mean in terms of quantity of gas; well simply taking methane as an example 2.5% by volume (or 2.5% of the total atmosphere in a vessel) is equivalent to 50% LEL and 5% volume is equivalent to 100% LEL. This is true for Methane but differs for all compounds 50% LEL of Pentane for example if 1.1% by Volume.