To Opt Out and No Longer Receive this Information, Click Unsubscribe at Bottom.
 Class 1: Groups A, B, C & D
Gases & Vapors
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 hazardous material present in the atmosphere.
Class I includes gases and vapors, and these are categorized into four groups that are labeled: A, B, C & D.
The materials in these four groups is based on the ignition temperature of the material, the explosion pressure of the material generated during an explosion; and other flammable characteristics.

In simple terms, the materials are rated by how easily they will ignite. And – with some materials there can be more than a fire. When ignited, they can explode, which creates a blast or shockwave (technically called explosion pressure). So, there can be different types of explosions, each with a different level of explosion pressure, and these are used to categorize the gasses and vapors in the four Class I Groups.

Group A: The only substance in Group A is Acetylene, which makes up only a very small percentage of all hazardous locations. Acetylene is a gas with an extremely high explosion pressure.

Group B is another relatively small percentage of all hazardous classification areas. This group includes Hydrogen and other gases with similar characteristics.

Groups C & D are by far the most common of the Class I Groups, with the highest percentage of hazardous locations. Present in Group D are the most common flammable gases and vapors, including Butane, Gasoline, Natural Gas and Propane.

List of 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
Bill Nagengast, President and Lighting Engineer, Solas Ray Lighting, holds over 20 patents in the lighting industry.
If you feel this information will help someone, please forward it to them so they can sign-up for our newsletter.
TJ-8 1.12.17