This part of IEC 60079-29 gives guidance on, and recommended practice for, the selection,installation, safe use and maintenance of electrically operated Group II equipment intendedfor use in industrial and commercial safety applications and Group I equipment inunderground coal mines for the detection and measurement of flammable gases complyingwith the requirements of IEC 60079-29-1 or IEC 60079-29-4.This standard is applicable for oxygen measurement for the purpose of inertisation whereexplosion protection is provided by the exclusion of oxygen instead of measuring theflammable gases or vapours present. A similar application is measuring oxygen wheninertising a goaf (mined out) area in an underground coal mine.This standard is a compilation of practical knowledge to assist the user, and applies toequipment, instruments and systems that indicate the presence of a flammable or potentiallyexplosive mixture of gas or vapour with air by using an electrical signal from a gas sensor toproduce a meter reading, to activate a visual or audible pre-set alarm or other device, or anycombination of these.Such equipment may be used as a means of reducing the risk whenever there is thepossibility of a risk to life or property specifically due to the accumulation of a flammable gasairmixture, by providing such warnings. It may also be used to initiate specific safetyprecautions (e.g. plant shutdown, evacuation, fire extinguishing procedures).This standard is applicable to fixed installations and transportable equipment. Similarly it isapplicable to the safe use of portable equipment. Since much modern equipment of this typealso includes oxygen deficiency detection and/or specific toxic gas sensors, some additionalguidance is given for these topics.For the purposes of this standard, except where specifically stated otherwise, flammablegases include flammable vapours.Mists are not covered by this standard due to measurement techniques currently used.