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Chemical Engineering vocabulary · Process Safety and Hazards

Lower explosive limit

Meaning in chemical engineering, with examples

nounCommon term

In chemical engineering, lower explosive limit means: The lowest concentration of a flammable gas or vapor in air that can burn or explode if ignited. Below it, the mixture is too lean to burn.

In Turkish: alt patlama sınırı, alt patlama limiti, LEL

How it is used

Abbreviated LEL (or LFL, lower flammable limit). Gas detectors read in % LEL and alarms are often set at around 10–20% LEL. Methane's LEL is about 5% by volume in air and its upper explosive limit (UEL) about 15%.

Example sentences

  1. The gas detector near the pump showed 25% of the lower explosive limit, so we evacuated the area.

  2. Nitrogen keeps the tank vapor space below the lower explosive limit of the solvent.

Common collocations

  • % LEL
  • upper explosive limit
  • flammable range
  • LEL alarm
  • below the LEL
  • flash pointThe lowest temperature at which a liquid gives off enough vapor to catch fire briefly when a flame or spark is brought near it.
  • purgeTo clear a vessel or pipe of air, flammable gas or toxic material by flushing it with an inert gas such as nitrogen, or with steam, before opening it or starting it up.
  • hazardAnything that could cause harm to people, the plant or the environment, such as a flammable gas, a toxic liquid, high pressure or a hot surface.
  • safety data sheetA standard document from the supplier that describes a chemical's hazards, safe handling, storage, first aid, firefighting and disposal, in 16 numbered sections.

More terms: Process Safety and Hazards

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