ISA 60079-29-2

This part of ISA-60079-29 gives guidance on, and recommended practice for , the selection, installation, safe use and maintenance of electrically operated group II apparatus intended for use in industrial and commercial safety applications for the detection and measurement of flammable gases complying with the requirements of ISA-60079-29-1 and ANSI/ISA- 12.13.04.

This standard is applicable for oxygen measurement for the purpose of inertisation where explosion protection is provided by the exclusion of oxygen instead of measuring the combustible gases or vapours present.

This standard is a compilation of practical knowledge to assist the user, and applies to apparatus, instruments and systems that indicate the presence of a flammable or potentially explosive mixture of gas or vapour with air by using an electrical signal from a gas sensor to produce a meter reading, to activate a visual or audible pre-set alarm or other device, or any combination of these.

Such apparatus may be used as a means of reducing the risk whenever there is the possibility of a risk to life or property specifically due to the accumulation of a combustible gas -air mixture, by providing such warnings. It may also be used to initiate specific safety precautions (e.g. plant shutdown, evacuation, fire extinguishing procedures).

This standard can be applied to all new permanent installations and, where reasonably practicable, to existing permanent installations. It is also applicable to temporary installations, whether new or existing.

This standard is applicable can be applied to all new permanent installations and, where reasonably practicable, to existing permanent installations. It is also applicable to temporary installations, whether new or existing.

NOTE When in explosive gas atmosphereareas, the apparatus should be so installed and used such that it is not capable of itself igniting a combustible gas-air mixture. It should therefore comply with the requirements of the area in which the apparatus is to be installed per the National Electrical Code^®, ANSI/NFPA 70, Articles 500-506.

For the purposes of this standard, except where specifically stated otherwise, flammable gases shall include flammable vapours.

This standard applies only to apparatus ( intended for use in industrial and commercial safety applications, involving areas classified in accordance with the National Electrical Code, ANSI/NFPA 70, Articles 500-506).

For the purposes of this standard, apparatus includes

a) fixed apparatus;

b) transportable apparatus; and

c) portable apparatus.

This standard is not intended to cover, but may provide useful information, for the following:

a) apparatus intended only for the detection of non-flammable toxic gases;

b) apparatus of laboratory or scientific type intended only for analysis or measurement purposes;

c) apparatus intended for underground mining applications (group I apparatus);

d) apparatus intended only for process control applications;

e) apparatus intended for applications in explosives processing and manufacture;

f) apparatus intended for the detection of a potentially flammable atmosphere resulting from dust or mist in air;