• Group A

acetylene

• Group B

formaldehyde (Gas)
hydrogen
manufactured gases containing >30% hydrogen (by volume)

• Group C

acetaldehyde
allyl alcohol
butyl mercaptan
n-butyraldehyde
carbon monoxide
crotonidehyde
dicyclopentadiene
diethyl ether
diethylamine
1, 1-dimethyl hydrazine
di-isopropylamine
dimethylamine
1, 4-dioxane
di-n-propylamine
epichlorohydrin
ethylene
ethylenimine
ethyl mercaptan
hydrogen cyanide
hydrogen selenide
hydrogen sulfide
isobutyridehyde
isopropyl glycidyl ether
methylacetylene
methyl ether
methyl formal
methyl mercaptan
monomethyl hydrazine
morpholine
nitroethane
nitromethane
2-nitropropane
propionaldehyde
n-propyl ether
tetrahydrofuran
triethylamine
UDMH 1,1-dimethyl hydrazine
valeraldehyde

• Group D

acetic acid (glacial)
acetone
acetonitrile
acrylonitrile
allyl chloride
ammonia
n-amyl acetate
sec-amyl acetate
benzene
butane
1-butanol (butyl alcohol)
2-butanol
n-butyl acetate
sec-butyl acetate
butylamine
butylene
chlorobenzene
cyclohexane
cyclohexene
cyclopropane
1, 1-dichloroethane
1, 2-dichloroethylene
1, 3-dichloropropene
di-isobutylene
ethane
ethanol (ethyl alcohol)
ethyl acetate
ethyl acrylate (inhibited)
ethlyamine
ethyl benzene
ethyl chloride
ethylenediamine (anhydrous)
ethylene dichloride
ethylene glycol monomethyl ether
ethyl formate
gasoline
heptane
heptene
hexane
hexenes
isoamyl acetate
isoamyl alcohol
isobutyl acrylate
isoprene
isopropyl acetate
isopropylamine
isopropyl ether
LPG (liquefied petroleum gas)
methane (natural gas)
methanol (methyl alcohol)
methyl acetate
methyl acrylate
methylamine
methyl cyclohexane
methyl ethyl ketone
methyl formate
methyl isobutyl ketone
methyl isocyanate
methyl methacrylate
2-methyl-1-propanol
(isobutyl alcohol)
2-methyl-2-propanol
naphtha (from petroleum, also benzine, ligroin)
nonane
nonene
octane
octene
pentane
1-pentanol (amyl alcohol)
2-pentanone
1-pentene
propane
1-propanol (propyl alcohol)
2-propanol (isopropyl alcohol)
n-propyl acetate
propylene
propylene dichloride
pyridine
styrene
toluene
turpentine
vinyl acetate
vinyl chloride
vinylidene chloride
xylenes

• Group E

Atmospheres containing combustible metal dusts regardless of resistivity, or other combustible dusts of similar hazardous characteristics having resistivity of <10⁵ ohm-cm (only division/zone 1, never 2; includes dusts of aluminum and magnesium and their commercial alloys)

• Group F

Atmospheres containing carbon black, charcoal, coke or coke dusts which have more than 8% total entrapped volatile material* or atmospheres containing these dusts sensitized by other materials so that they present an explosion hazard, and having resistivity >100 ohm-cm but equal to or < 10⁸ ohm-centimeter.

*Carbon black per ASTM D 1620 and charcoal coke and coke dust per ASTM D271.

• Group G

Atmospheres containing combustible dusts with resistivity of 10⁵ ohm-centimeter or greater and not included in Groups E or F such as flour, grain, wood, plastic, and chemicals.