Abstract： IEC 60079-10:2002 pdf free download.Electrical apparatus for explosive gasatmospheres - Part 10: Classification of hazardous areas. 2.5.3 zone 2 place in which an explosive atmosphere consisting of a mixture with air of flammable substances...

IEC 60079-10:2002 pdf free download.Electrical apparatus for explosive gasatmospheres - Part 10: Classification of hazardous areas.

2.5.3

zone 2

place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only

[1EV 426-03-05, modified]

NOTE 1 In this definition, the word persist means the total time for which the flammable atmosphere will exist. This will normally comprise the total of the duration of the release, plus the time taken for the flammable atmosphere to disperse after the release has stopped. (The term persistence time as used In annex B refers specifically to only one part of the total time for which the

flammable atmosphere will exist.)

NOTE 2 Indications of the frequency of the occurrence and duration may be taken from codes relating to specific industries or

applications.

2.6

source of release

point or location from which a flammable gas, vapour, or liquid may be released into the atmosphere in such a way that an explosive gas atmosphere could be formed

(1EV 426-03-06, modified)

2.7

grades of release

there are three basic grades of release, as listed below in order of decreasing frequency and likelihood of the explosive gas

atmosphere being present;

a) continuous grade;

b) primary grade;

c) secondary grade.

A source of release may give rise to any one of these grades of release, or to a combination of more than one.

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