UL Standard for Safety Explosive Atmospheres – Part 29-2: Gas Detectors – Selection, Installation, Use and Maintenance of Detectors for Flammable Gases and Oxygen
|Publication Date:||15 October 2018|
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 flammable gases or vapours present. A similar application is measuring oxygen when inertising a goaf (mined out) area in an underground coal mine.
This standard is a compilation of practical knowledge to assist the user, and applies to equipment, 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 equipment 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 flammable 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 is applicable to fixed installations and transportable equipment. Similarly it is applicable to the safe use of portable equipment. Since much modern equipment of this type also includes oxygen deficiency detection and/or specific toxic gas sensors, some additional guidance is given for these topics.
For the purposes of this standard, except where specifically stated otherwise, flammable gases include flammable vapours.
Mists are not covered by this standard due to measurement techniques currently used.
This standard applies to Group II equipment (i.e. equipment intended for use in industrial and commercial safety applications, involving areas classified in accordance with IEC 60079-10-1) and Group I equipment.
For the purposes of this standard, equipment includes
a) fixed equipment including equipment mounted on a vehicle;
b) transportable equipment; and
c) portable equipment.
This standard is not intended to cover, but may provide useful information, for the following:
a) equipment intended only for the detection of non-flammable toxic gases;
b) equipment of laboratory or scientific type intended only for analysis or measurement purposes;
c) equipment intended only for process control applications;
d) equipment intended for applications in explosives processing and manufacture;
e) equipment intended for the detection of a explosive atmosphere resulting from dust or mist in air.