What is LEL& UEL
WHAT IS %LEL AND %UEL
The primary risk associated with combustible gases and vapors is the possibility of explosions.
Explosion, like fire, requires three elements: fuel, Oxygen, and an ignition source.
Each combustible gas or vapor will ignite only within a specific range of fuel/Oxygen mixtures. Too little or too much gas will not ignite.
These conditions are defined as the Lower Explosive Limit (LEL) and the Upper Explosive Limit (UEL). Any amount of gas between the two limits is explosive.
It is important to note that each gas has its own LEL and UEL, as shown in the chart below.
Lower Explosive Limit (LEL): The minimum vapor concentration (by percent) in which a liquid can form an ignitable mixture in air is called the “lower explosive limit.” Below this limit, vapor concentration is too lean to support combustion.
Upper Explosive Limit (UEL): The maximum vapor concentration (by percent) in which a liquid can form an ignitable mixture in air is called the “upper explosive limit.” Above this limit, vapor concentration is too rich to support combustion.
Explosive Range: The range between the LEL and UEL is the “explosive range.” If a source of ignition such as a flame, spark, or static electricity is present, an explosion may occur. This may also be referred to as the “flammable range.” The graph below illustrates the explosive range of gasoline.
The primary risk associated with combustible gases and vapors is the possibility of explosions.
Explosion, like fire, requires three elements: fuel, Oxygen, and an ignition source.
Each combustible gas or vapor will ignite only within a specific range of fuel/Oxygen mixtures. Too little or too much gas will not ignite.
These conditions are defined as the Lower Explosive Limit (LEL) and the Upper Explosive Limit (UEL). Any amount of gas between the two limits is explosive.
It is important to note that each gas has its own LEL and UEL, as shown in the chart below.
Lower Explosive Limit (LEL): The minimum vapor concentration (by percent) in which a liquid can form an ignitable mixture in air is called the “lower explosive limit.” Below this limit, vapor concentration is too lean to support combustion.
Upper Explosive Limit (UEL): The maximum vapor concentration (by percent) in which a liquid can form an ignitable mixture in air is called the “upper explosive limit.” Above this limit, vapor concentration is too rich to support combustion.
Explosive Range: The range between the LEL and UEL is the “explosive range.” If a source of ignition such as a flame, spark, or static electricity is present, an explosion may occur. This may also be referred to as the “flammable range.” The graph below illustrates the explosive range of gasoline.
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