1. Definitions

The definitions given below have been drawn up by an international commission (source: IEC Electropedia, also known as IEV online) or defined in international (IEC) and European (EN) standards for the evaluation of flammable, oxygen and toxic gas detectors. Additional information is provided in the form of comments.

• Explosive gas atmosphere

  Mixture of flammable substances in gas or vapor form with air, which, under atmospheric conditions and after ignition, allows self-sustained propagation.

• Lower explosive limit, LEL

  Concentration of flammable gases and vapors in air, below which an explosive gaseous atmosphere will not form.

• Upper explosive limit, UEL

  Concentration of flammable gases, vapors...