Maximum experimental safe gap (MESG) is a standardized measurement of how easily a gas flame will pass through a narrow gap bordered by heat-absorbing metal.
MESG is used to classify flammable gases for the design and/or selection of electrical equipment in hazardous areas, and flame arrestor devices.
[1] The National Electric Code classifies Class I hazardous locations into different groups depending on the respective MESG's of gases in the area.
[2] http://site.ul.com/global/documents/offerings/services/hazardouslocations/CI_groups.pdf[permanent dead link] This standards- or measurement-related article is a stub.
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