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A 5% displayed LFL reading for methane, for example, would be equivalent to 5% multiplied by 4.4%, or approximately 0.22% methane by volume at 20 degrees C. Control of the explosion hazard is usually achieved by sufficient natural or mechanical ventilation, to limit the concentration of flammable gases or vapors to a maximum level of 25% of ...
Any mixture of methane and air will therefore lie on the straight line between pure methane and pure air – this is shown as the blue air-line. The upper and lower flammability limits of methane in air are located on this line, as shown (labelled UEL and LEL, respectively). The stoichiometric combustion of methane is: CH 4 + 2O 2 → CO 2 + 2H ...
The lower flammability limit or lower explosive limit (LFL/LEL) represents the lowest air to fuel vapor concentration required for combustion to take place when ignited by an external source, for any particular chemical. [29] Any concentration lower than this could not produce a flame or result in combustion.
The lower flammability limit (LFL), [1] usually expressed in volume per cent, is the lower end of the concentration range over which a flammable mixture of gas or vapour in air can be ignited at a given temperature and pressure. The flammability range is delineated by the upper and lower flammability limits. Outside this range of air/vapor ...
UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing, is a plastics flammability standard released by Underwriters Laboratories of the United States. [1] The standard determines the material's tendency to either extinguish or spread the flame once the specimen has been ignited.
Flammable gases – Gases which at 20 °C and a standard pressure of 101.3 kPa: are ignitable when in a mixture of 13 percent or less by volume with air; or; have a flammable range with air of at least 12 percentage points regardless of the lower flammable limit. Alternative sign. Division 2.1 Non-flammable non-toxic gases – Gases which:
Category 1A includes extremely flammable gases ignitable at 20 °C and standard pressure of 101.3 kPa, pyrophoric gases, and chemically unstable gases that may react in the absence of oxygen. Category 1B gases meet the flammability criteria of 1A, but are not pyrophoric or chemically unstable and have a lower flammability limit in air.
Assume a closed system (e.g. a container or process vessel), initially containing air, which shall be prepared for safe introduction of a flammable gas, for instance as part of a start-up procedure. The system can be flushed with an inert gas to reduce the concentration of oxygen so that when the flammable gas is admitted, an ignitable mixture ...