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Class I -
Gases or Vapors
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Class II
- Dust
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Class
III - Fibers
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Division 1
Hazardous vapors present |
Division 1
Air suspended |
Division 1
Fibers handled, manufactured, stored |
Division 2
Hazardous vapors contained, but may be present |
Division 2
Surface accumulated, non-air suspended |
Division 2
Fibers handled or stored |
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Groups for both
Division 1 and Division 2
Group A - Atmospheres containing acetylene
Group B - Atmospheres containing hydrogen or gases or vapors of
equivalent hazard such as manufactured gas
Group C - Atmospheres containing ethyl-ether vapors, ethylene or
cyclo-propane
Group D - Atmospheres containing gasoline, hexane, naptha, benzene,
butane, propane, alcohol, acetone, benzol, lacquer solvent vapors, or
natural gas |
Groups for both
Division 1 and Division 2
Group E - Atmospheres containing metal dust including aluminum,
magnesium, 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 |
No Groups for Class III
Atmospheres containing textile, wood or synthetic fibers
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Group A
acetylene
Group B
acrolein (inhibited) (2)
arsine
butadiene (1)
ethylene oxide (2)
hydrogen
manufactured gases containing
more than 30% hydrogen
(by volume)
propylene oxide (2)
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 (3)
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 |
Group D (cont'd)
2-methyl-1 -propanol
(isobutyl alcohol)
2-methyl-2-propanol
(tertiary butyl alcohol)
petroleum naphtha (4)
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
containing metal dust, including
aluminum, magnesium, and their
commercial alloys, and other
metals of similarly hazardous
characteristics.
Group F
containing carbon black,
coal or coke dust.
Group G
containing flour,
starch or grain dust. |
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(1) Group D equipment
shall be permitted for this atmosphere if such equipment is isolated in
accordance with Section 501-5(a) of National Electric Code by sealing all
conduit 1/2 inch size or larger.
(2) Group C equipment shall be permitted for this
atmosphere if such equipment is isolated in accordance with Section 501-5(a)
of National Electric Code by sealing all conduit 1/2-inch size or larger.
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For classification of areas involving ammonia
atmosphere,
(3) See Safety Code for Mechanical Refrigeration
(ANSI/ASHRAE 15-1978) and Safety Requirements for the Storage and Handling
of Anhydrous Ammonia (ANSI/CGA G2.1-1972).
(4) A saturated hydrocarbon mixture boiling in the
range 20-135 -C (68-275 -F). Also known by the synonyms benzine, ligroin,
petroleum ether, or naphtha. |
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