To protect against toxic gases, contaminants have permissible exposure limits ( PELs ), which are set by OSHA . Work also cannot continue if the concentration of a material reaches or exceeds 10 % of its lower explosive limit.
22.
Auto ignition point of blast furnace gas is approximate and it has LEL ( Lower Explosive Limit ) of 27 % & UEL ( Upper Explosive Limit ) of 75 % in an air-gas mixture at normal temperature and pressure.
23.
Unclassified locations on chemical and other plant are present where it is absolutely certain that the hazardous gas is diluted to a concentration below 25 % of its lower flammability limit ( or lower explosive limit ( LEL ) ).
24.
Auto ignition point of blast furnace gas is approximate and it has LEL ( Lower Explosive Limit ) of 27 % & UEL ( Upper Explosive Limit ) of 75 % in an air-gas mixture at normal temperature and pressure.
25.
Concentrated acetic acid can be ignited only with difficulty at standard temperature and pressure, but becomes a flammable risk in temperatures greater than, and can form explosive mixtures with air at higher temperatures ( explosive limits : 5.4 16 % ).
26.
"Although reducing fuel tank temperatures by only a few degrees may seem insignificant, incremental reductions of fuel-air temperatures in airplane fuel tanks could keep fuel tank temperatures below the lower explosive limits of the fuel, " the board noted in its recommendation.
27.
Aerosol of flammable dust can be ignited as well, resulting in a dust explosion; the lower explosive limit usually lies between 50 and 1000 g / m 3; finer dusts tend to be more explosive and requiring less spark energy to set off.
28.
However, the Environmental Protection Agency's ( EPA ) " Newtown Creek / Greenpoint Oil Spill Study Brooklyn, New York " states that vapor concentrations in " some commercial establishments " were found " above the Upper Explosive Limit " ( page 7 ).
29.
For this reason, the U . S . Mine Safety and Health Administration requires that groups of miners in the United States carry gas detection equipment that can detect common gases, such as CO, O 2, H 2 S, CH 4, as well as calculate % Lower Explosive Limit.
30.
For the common industrial hydrocarbon gases and solvents, the minimum ignition energy required for ignition of vapor-air mixture is lowest for the vapor concentration roughly in the middle between the lower explosive limit and the upper explosive limit, and rapidly increases as the concentration deviates from this optimum to either side.
