Upper Flammable Limit (UFL) – Definition and Pronunciation
What is UFL?
Upper flammable limit (UFL) The concentration of a hydrocarbon gas in air above which there is insufficient air to support and propagate combustion. Sometimes referred to as “upper explosive limit (UEL)“.
Examples of UFL
An ignited cloud will “flash back” across all its flammable mass (i. e. that part within the flammable range – between the UFL and LFL). It will then burn at the UFL boundary until the entire gas is consumed.
From “Assessing the safety risks of LNG bunkering”.
A source of ignition in those areas, where the gas concentration is between the LFL and the UFL, will create a fire. The burning gas, becoming lighter than air, might generate a fire cloud and this cloud might be transported very far from the site of the accident depending on the atmospheric conditions.
From “LNG Transportation Risks and Essential Insights”.
However, Reference 7 stated, “for typical humidities at Maplin (60-90 %), for liquid spills on seawater, the propane vapor clouds cease to be visible at dispersion distances well short of the LFL point but beyond the upper flammable limit (UFL) point”.
From “The Controlled Dispersion of Liquid Spill and Vapour Emission Incidents by Water Spray”.
Pronunciation of UFL
