Understanding Hazardous Locations In addition to classifying Hazardous Locations by Class and Division, each location is also classified by its "Group."  A Group refers to the type of flammable material present in the atmosphere.  See below for a list of all the groups and their materials. 

Group A
  • Acetylene

Group B

  • Acrolein (inhibited)
  • Arsine
  • Butadiene
  • Ethylene oxide
  • Hydrogen
  • Manufactured gases containing more than 30% hydrogen (by volume)
  • Propylene oxide
  • Propylnitrate
Group C
  • Acetaldehyde
  • Allyl alcohol
  • n-butyraidehyde
  • Carbon monoxide
  • Crotonaldehyde
  • Cyclopropane
  • Diethyl ether
  • Diethylamine
  • Epichlorohydrin
  • Ethylene
  • Ethylenimine
  • Ethyl mercaptan
  • Ethyl sulfide
  • Hydrogen cyanide
  • Hydrogen sulfide
  • Morpholine
  • 2-nitropropane
  • Tetrahydrofuran
  • Unsymmetrical dimethyl hydrazine (UDMH 1, 1-dimethyl hydrazine)

Group D

  • Acetic acid (glacial)
  • Acetone
  • Acrylonitrile
  • Ammonia
  • Benzene
  • Butane
  • 1-butanol (butyl alcohol)
  • 2-butanol (secondary butyl alcohol)
  • n-butyl acetate
  • Isobutyl acetate
  • Di-isobutylene
  • Ethane
  • Ethanol (ethyl alcohol)
  • Ethyl acetate
  • Ethyl acrylate (inhibited)
  • Ethylene diamine (anhydrous)
  • Ethylene dichloride
  • Ethylene glycol monomethyl ether
  • Gasoline
  • Heptanes
  • Hexanes
  • Isoprene
  • Isopropyl ether
  • Mesityl oxide
  • Methane (natural gas)
  • Methanol (methyl alcohol)
  • 3-methyl-1 butanol (isoamyl alcohol)
  • Methyl ethyl ketone
  • Methyl isobutyl ketone
  • 2-methyl-1 -propanol (isobutyl alcohol)
  • 2-methyl-2-propanol (tertiary butyl alcohol)
  • Petroleum naphtha
  • Pyridine
  • Octanes
  • Pentanes
  • 1-pentanol (amyl alcohol)
  • Propane
  • 1-propanol (propyl alcohol)
  • 2-propanol (isopropyl alcohol)
  • Propylene
  • Styrene
  • Toluene
  • Vinyl acetate
  • Vinyl chloride
  • Xylenes

Group E

  • Atmospheres containing metal dust, including aluminum, magnesium, and their commercial alloys, and other metals of similarly hazardous characteristics.

Group F

  • Atmospheres containing carbon black, coal or coke dust.

Group G

  • Atmospheres containing flour, starch or grain dust.