Flammable liquid Lower explosive limits

The lower flammable limit (LFL) or lower explosive limit (LEL) is the minimum concentration of vapor in air below which a flame is not propagated when an ignition source is present (61—64). Below this concentration, the mixture is considered too lean to bum. The lower flammable limit and the flash point of a flammable liquid are closely related by the liquid s vapor pressure characteristics. 

Isoprene is classified by the ICC as a flammable liquid requiring a red label (124). Its flash point is —54°C with a lower explosive limit (LEL) of 1.5%... 

The flammability of a liquid (as vapor) or that of a gas falls between two fairly definite limits of concentrations of the vapor (or gas) in the air. These are the lower explosive limit (LEL) and the upper explosive limit (UEL). These concentration limits in air are also known as the lower and upper flammable limits. The LEL is the minimum concentration of the vapor (or gas) in air below which a flame is not propagated on contact with a source of ignition. There is also a maximum concentration of vapor... 

The third component of a fire is the vapour, which can mix with air, over the surface of a flammable liquid. Solvent vapours will only burn in air over a restricted concentration range bounded by the UEL (upper explosive limit) and LEL (lower explosive limit). Table 9.2 sets out for a typical range of flammable solvents their UEL and LEL values and their flash points, which are effectively the temperatures at which the solvent-saturated air attains the LEL. 

Lower explosive limit Lower limit of flammability or explosibihty of a gas or vapor at ordinary ambient temperatures expressed in percent of the gas vapor in air by volume. Tests for comparative flammability of liquids, UI 340. Laboratories Incorporated Underwriters, New York, 1997. 

Lysergic acid methylpropylamide Lethal dose-50 The dose of a drug that kills half of the test population Like dissolves like Linear dynamic range Lower explosive limit same as LEL, lower flammability range Lower flammability range Ligand field theory Liquid/liquid extraction such as performed in a separatory funnel or Soxh-let extraction unit Limit of detection... 

Such controls may be the replacement of a fine dusty material by a less dusty granular material or reducing the flammable gas to the absolute minimum. Limiting the concentration to avoid the explosive range with mechanical systems linked to ventilation which may be actuated via gas or flow detectors (including alarms) should be considered. In the case of combustible liquids the objective should be to reduce the concentration of any mist formed, below the lower explosion limit, which in turn will ensure it is sufficiently below its flashpoint to prevent explosion. 

The flammable range, sometimes called the explosive range, of flammable gases and the vapors of flammable liquids is the numerical difference between their upper and lower explosive limits. Thus, the flammable range of gasoline vapor is 6.2 percent by volume. 

When a flammable liquid is sprayed as fine droplets into the air, a flammable mixture can result, which may burn or explode. The mist or spray may be formed by condensation of saturated vapors or by mechanical means [40]. As the particle sizes of the liquid become greater than 0.01 mm diameter, the lower flammability limit of the material becomes lower while above 0.01 mm, the LEL is about the same as the vapor. Mechanical engine crankcase explosions of oil mist in air are hazardous, and current practice is to apply explosion relief valves to the crankcase. 

The results for lower (LEL) and upper (UEL) explosive limits in air are presented in Table 3-1. The LEL and UEL values are the lower and upper concentrations (expressed as volume %) for flammability. The tabulation also provides the freezing and boiling point temperatures which are helpful in determining whether the substance is a gas, liquid or solid at ambient conditions. The tabulation is based on both experimental data and estimated values. 

Tetrahydrofuran is a flammable liquid with a flash point of 6°E and explosive limits ranging from 2% (lower) to 11.8 % (upper). It is incompatible with strong oxidizers and lithium-aluminum alloys. Peroxides may accumulate upon prolonged storage in the air. 

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