Gas group, temperature class and autoignition temperature by substance

Hazardous area (explosive atmosphere) classification of individual flammable gases, vapours and combustible dusts. Each record is one substance as classified by one publisher, giving the apparatus / gas group (IIA, IIB, IIC, IIB+H2 under IEC 60079 and ATEX, or Class I Group A/B/C/D under the US National Electrical Code), the temperature class (T1 to T6), and the autoignition temperature the publisher prints. Answers 'is toluene IIA or IIB', 'what temperature class is acetone', 'MEK autoignition temperature for explosion proof equipment', 'NEC Group C equivalent IEC gas group', 'what gas group is hydrogen sulphide', and 'ethylene gas group and T class'. Publishers disagree on the autoignition temperature of the same substance -- hydrogen is printed as 500 C, 520 C and 560 C by three different manufacturers, and ethylene as 450 C and 490 C -- and because the temperature class is derived from that number the disagreement changes which equipment is legal to install. Every value is quoted from the page that printed it and attributed, so the disagreements are visible rather than averaged away.

1 record where two or more sources state different values. Both sides are reproduced on the record page, each with its own source and quote.

The data

Where this came from

Every record above links the page it was taken from and quotes the sentence that states it. These are the 4 sources this dataset was assembled from.

• e2s.comhttps://www.e2s.com/guide-for-hazardous-areas/apparatus-groups-and-common-flammable-ga
• cortemgroup.comhttps://www.cortemgroup.com/en/news/the-zones-of-the-plant-the-groups-and-the-temperature-classes-of-gases
• ldpi-inc.comhttps://ldpi-inc.com/resources/classification-codes/class-1-locations/
• exknowledge.comhttps://exknowledge.com/pages/gas-groups.html

Machine-readable

• data.jsonThe whole dataset — every record with its source URL and source quote.
• Open Knowledge Format bundleOne JSON object per line — every record's frontmatter and quoted span exactly as it is held here, in one fetch.
• How this is made and checkedWhat "verified against source" does and does not mean.

60 records. last verified against source 2026-08-06. due for re-check by 2028-08-05.

Licence. Facts extracted from freely published manufacturer and industry reference pages. Gas group and temperature class assignments are safety classifications and the underlying values are facts, not copyrightable expression. The authoritative documents (NFPA 497, IEC 60079-20-1) are not reproduced and were not opened -- the fact is taken, never the document. No bulk take from any single source: records come one or two substances at a time from five separate publishers.