CHAPTER 5
EXAMPLES AND TABLES
COMMENTARY AT 500.6(B)(3) INFORMATIONAL NOTE NO. 3
Section 500.6(B) separates combustible dusts into three Class II groups — E, F, and G — depending on their properties.
Selected combustible dusts have been evaluated for the purpose of designating the appropriate dust group — E, F, or G, and this information is used to
properly select electrical equipment for use in Class II locations. These selected materials, with their group classification and relevant physical
properties, are listed in NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for
Electrical Installations in Chemical Process Areas.
Commentary Table 500.2 Selected Combustible Materials
Chemical Name
Acetal, Linear
Acetoacet-p-phenetidide
Acetoacetanilide
Acetylamino-t-nitrothiazole
Acrylamide Polymer
Acrylonitrile Polymer
Acrylonitrile-Vinyl Chloride-Vinylidenechloride copolymer
(70-20-10)
Acrylonitrile-Vinyl Pyridine Copolymer
Adipic Acid
CAS No.
122-82-7
102-01-2
124-04-9
NEC
Group
Code
Layer or Cloud Ignition
Temp. (ºC)
G
G
G
G
G
G
G
NL
NL
M
440
560
440
450
240
460
210
G
G
M
240
550
Alfalfa Meal
Alkyl Ketone Dimer Sizing Compound
Allyl Alcohol Derivative (CR-39)
Almond Shell
Aluminum, A422 Flake
Aluminum, Atomized Collector Fines
Aluminum — cobalt alloy (60-40)
Aluminum — copper alloy (50-50)
Aluminum — lithium alloy (15% Li)
Aluminum — magnesium alloy (Dowmetal)
Aluminum — nickel alloy (58-42)
Aluminum — silicon alloy (12% Si)
Amino-5-nitrothiazole
Anthranilic Acid
Apricot Pit
Aryl-nitrosomethylamide
Asphalt
Aspirin [acetol (2)]
Azelaic Acid
Azo-bis-butyronitrile
Benzethonium Chloride
Benzoic Acid
Benzotriazole
Beta-naphthalene-axo-dimethylaniline
Bis(2-hydroxy-5-chlorophenyl) Methane
Bisphenol-A
Boron, Commercial Amorphous (85% B)
Calcium Silicide
Carbon Black (More Than 8% Total Entrapped Volatiles)
Carboxymethyl Cellulose
Carboxypolymethylene
Cashew Oil, Phenolic, Hard
Cellulose
Cellulose Acetate
Cellulose Acetate Butyrate
7429-90-5
121-66-4
118-92-3
8052-42-4
50-78-2
109-31-9
78-67-1
65-85-0
95-14-7
97-23-4
80-05-7
7440-42-8
9000-11-7
G
G
G
G
E
E
E
E
E
E
E
E
G
G
G
G
F
G
G
G
G
G
G
G
G
G
E
E
F
G
G
G
G
G
G
NL
CL
CL
NL
M
NL
M
M
CL
M
M
NL
M
NL
NL
200
160
500
200
320
550
570
830
400
430
540
670
460
580
230
490
510
660
610
350
380
440
440
175
570
570
400
540
290
520
180
260
340
370
Cellulose Triacetate
Charcoal (Activated)
Charcoal (More Than 8% Total Entrapped Volatiles)
Cherry Pit
Chlorinated Phenol
Chlorinated Polyether Alcohol
Chloroacetoacetanilide
Chromium (97%) Electrolytic, Milled
Cinnamon
Citrus Peel
Coal, Kentucky Bituminous
Coal, Pittsburgh Experimental
Coal, Wyoming
Cocoa Bean Shell
Cocoa, Natural, 19% Fat
Coconut Shell
Coke (More Than 8% Total Entrapped Volatiles)
Cork
Corn
Corn Dextrine
Corncob Grit
Cornstarch, Commercial
Cornstarch, Modified
Cottonseed Meal
Coumarone-Indene, Hard
Crag No. 974
Cube Root, South America
Di-alphacumyl Peroxide, 40-60 on CA
Diallyl Phthalate
Dicyclopentadiene Dioxide
Dieldrin (20%)
Dihydroacetic Acid
Dimethyl Isophthalate
Dimethyl Terephthalate
64365-11-3
101-92-8
7440-47-3
533-74-4
83-79-4
80-43-3
131-17-9
60-57-1
1459-93-4
120-61-6
G
F
F
G
G
G
G
E
G
G
F
F
F
G
G
G
F
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
NL
NL
M
NL
CL
M
NL
NL
NL
M
M
430
180
220
570
460
640
400
230
270
180
170
180
370
240
220
210
250
370
240
330
200
200
520
310
230
180
480
420
550
430
580
570
Dinitro-o-toluamide
Dinitrobenzoic Acid
Diphenyl
Ditertiary-butyl-paracresol
Dithane m-45
Epoxy
Epoxy-bisphenol A
Ethyl Cellulose
Ethyl Hydroxyethyl Cellulose
Ethylene Oxide Polymer
Ethylene-maleic Anhydride Copolymer
FerbamTM
Ferromanganese, Medium Carbon
Ferrosilicon (88% Si, 9% Fe)
Ferrotitanium (19% Ti, 74.1% Fe, 0.06% C)
Flax Shive
Fumaric Acid
Garlic, Dehydrated
Gilsonite
Green Base Harmon Dye
Guar Seed
Gulasonic Acid, Diacetone
Gum, Arabic
Gum, Karaya
Gum, Manila
Gum, Tragacanth
Hemp Hurd
Hexamethylene Tetramine
Hydroxyethyl Cellulose
Iron, 98% H2 Reduced
Iron, 99% Carbonyl
Isotoic Anhydride
L-sorbose
Lignin, Hydrolized, Wood-type, Fine
Lignite, California
148-01-6
92-52-4
128-37-0
8018-01-7
14484-64-1
12604-53-4
8049-17-0
110-17-8
12002-43-6
9000-65-1
100-97-0
13463-40-6
G
G
G
G
G
G
G
G
G
G
G
G
E
E
E
G
G
G
F
G
G
G
G
G
G
G
G
G
G
E
E
G
G
G
F
NL
NL
M
NL
NL
NL
CL
NL
NL
NL
CL
M
NL
NL
NL
CL
S
NL
NL
M
NL
500
460
630
420
180
540
510
320
390
350
540
150
290
800
380
230
520
360
500
175
500
420
260
240
360
260
220
410
410
290
310
700
370
450
180
Lycopodium
Malt Barley
Manganese
Magnesium, Grade B, Milled
Manganese Vancide
Mannitol
Methacrylic Acid Polymer
Methionine (l-methionine)
Methyl Cellulose
Methyl Methacrylate Polymer
Methyl Methacrylate-ethyl Acrylate
Methyl Methacrylate-styrene-butadiene
Milk, Skimmed
N,N-Dimethylthio-formamide
Nitropyridone
Nitrosamine
Nylon Polymer
Para-oxy-benzaldehyde
Paraphenylene Diamine
Paratertiary Butyl Benzoic Acid
Pea Flour
Peach Pit Shell
Peanut Hull
Peat, Sphagnum
Pecan Nut Shell
Pectin
Pentaerythritol
Petrin Acrylate Monomer
Petroleum Coke (More Than 8% Total Entrapped Volatiles)
Petroleum Resin
Phenol Formaldehyde
Phenol Formaldehyde, Polyalkylene-p
Phenol Furfural
Phenylbetanaphthylamine
Phthalic Anydride
7439-96-5
69-65-8
63-68-3
9011-14-7
100703-82-0
63428-84-2
123-08-0
106-50-3
98-73-7
94114-14-4
8002-03-7
5328-37-0
115-77-5
7659-34-9
64742-16-1
9003-35-4
9003-35-4
26338-61-4
135-88-6
85-44-9
G
G
E
E
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
F
G
G
G
G
G
G
M
NL
NL
NL
M
NL
CL
M
M
M
NL
NL
NL
M
190
250
240
430
120
460
290
360
340
440
440
480
200
230
430
270
430
380
620
560
260
210
210
240
210
200
400
220
500
580
290
310
680
650
Phthalimide
Pitch, Coal Tar
Pitch, Petroleum
Polycarbonate
Polyethylene, High Pressure Process
Polyethylene, Low Pressure Process
Polyethylene Terephthalate
Polyethylene Wax
Polypropylene (no antioxidant)
Polystyrene Latex
Polystyrene Molding Compound
Polyurethane Foam, Fire Retardant
Polyurethane Foam, No Fire Retardant
Polyvinyl Acetate
Polyvinyl Acetate/Alcohol
Polyvinyl Butyral
Polyvinyl Chloride-dioctyl Phthalate
Potato Starch, Dextrinated
Pyrethrum
Rayon (Viscose) Flock
Red Dye Intermediate
Rice
Rice Bran
Rice Hull
Rosin, DK
Rubber, Crude, Hard
Rubber, Synthetic, Hard (33% S)
Safflower Meal
Salicylanilide
Sevin
Shale, Oil
Shellac
Sodium Resinate
Sorbic Acid (Copper Sorbate or Potash)
Soy Flour
85-41-6
65996-93-2
68187-58-6
9002-88-4
9002-88-4
25038-59-9
68441-04-8
9003-07-0
9003-53-6
9003-53-6
9009-54-5
9009-54-5
9003-20-7
9002-89-5
63148-65-2
9005-25-8
8003-34-7
61788-77-0
8050-09-7
9006-04-6
64706-29-2
87-17-2
63-25-2
68308-34-9
9000-59-3
61790-51-0
110-44-1
68513-95-1
G
F
F
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
F
G
G
G
G
M
NL
NL
NL
NL
NL
NL
NL
NL
NL
NL
NL
NL
NL
NL
NL
M
NL
630
710
630
710
380
420
500
400
420
500
560
390
440
550
440
390
320
440
210
250
175
220
490
220
390
350
320
210
610
140
400
220
460
190
Soy Protein
Stearic Acid, Aluminum Salt
Stearic Acid, Zinc Salt
Styrene Modified Polyester-Glass Fiber
Styrene-acrylonitrile (70-30)
Styrene-butadiene Latex (>75% styrene)
Styrene-maleic Anhydride Copolymer
Sucrose
Sugar, Powdered
Sulfur
Tantalum
Terephthalic Acid
Thorium (contains 1.2% O)
Tin, 96%, Atomized (2% Pb)
Titanium, 99% Ti
Titanium Hydride (95% Ti, 3.8% H)
Trithiobisdimethylthio-formamide
Tung, Kernels, Oil-free
Urea Formaldehyde Molding Compound
Urea Formaldehyde-phenol Formaldehyde
Vanadium, 86.4%
Vinyl Chloride-acrylonitrile Copolymer
Vinyl Toluene-acrylonitrile Butadiene
Violet 200 Dye
Vitamin B1, Mononitrate
Vitamin C
Walnut Shell, Black
Wheat
Wheat Flour
Wheat Gluten, Gum
Wheat Starch
Wheat Straw
Wood Flour
Woodbark, Ground
Yeast, Torula
9010-10-0
637-12-7
557-05-1
100-42-5
9003-54-7
903-55-8
9011-13-6
57-50-1
57-50-1
7704-34-9
7440-25-7
100-21-0
7440-29-1
7440-31-5
7440-32-6
7704-98-5
8001-20-5
9011-05-6
25104-55-6
7440-62-2
9003-00-3
76404-69-8
59-43-8
50-81-7
130498-22-5
100684-25-1
68602-94-8
G
G
G
G
G
G
G
G
G
G
E
G
E
E
E
E
G
G
G
G
E
G
G
G
G
G
G
G
G
G
G
G
G
G
G
M
NL
NL
CL
CL
CL
NL
CL
CL
CL
NL
NL
NL
NL
NL
260
300
510
360
500
440
470
350
370
220
300
680
270
430
330
480
230
240
460
240
490
470
530
175
360
280
220
220
360
520
380
220
260
250
260
Zirconium Hydride
Zirconium (contains 0.3% O)
7704-99-6
7440-67-7
E
E
CL
270
330
Notes:
1. Normally, the minimum ignition temperature of a layer of a specific dust is lower than the minimum ignition temperature of a cloud of that dust. Since this is not universally
true, the lower of the two minimum ignition temperatures is listed. If no symbol appears in the “Code” column, then the layer ignition temperature is shown. “CL” means the cloud
ignition temperature is shown. “NL” means that no layer ignition temperature is available, and the cloud ignition temperature is shown. “M” signifies that the dust layer melts
before it ignites; the cloud ignition temperature is shown. “S” signifies that the dust layer sublimes before it ignites; the cloud ignition temperature is shown.
2. Certain metal dusts may have characteristics that require safeguards beyond those required for atmospheres containing the dusts of aluminum, magnesium, and their
commercial alloys. For example, zirconium and thorium dusts may ignite spontaneously in air, especially at elevated temperatures.
3. Due to the impurities found in coal, its ignition temperatures vary regionally and ignition temperatures are not available for all regions in which coal is mined.
Source: NFPA 499-2008, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process
Areas, Table 4.5.2.
COMMENTARY AT 500.6(A)(4) INFORMATIONAL NOTE NO. 2
Flammable gases, flammable liquid–produced vapors, and combustible liquid–produced vapors are separated into four Class I groups — A, B, C, and D
(or three Class I zone groups — IIC, IIB, and IIA; see 505.6) depending on their properties. By grouping explosive mixtures that have similar igniting
current ratios and maximum safe clearances between parts of a joint in an enclosure, equipment can be designed for the entire group rather than an
individual chemical. The Code requirements for Class I locations do not vary for different kinds of gas or vapor contained in a group, except as in
Exceptions No. 1 and No. 2 to 500.6(A)(2). This method makes it easier to properly select equipment designed for use in the particular group involved.
Selected combustible materials have been evaluated for the purpose of designating the appropriate gas group — A, B, C, or D (or IIC, IIB, or IIA), and
this information is used to properly select electrical equipment for use in Class I locations. These materials, with their group classification and relevant
physical properties, are listed in NFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous
(Classified) Locations for Electrical Installations in Chemical Process Areas.
Many documents used to determine an area’s classification do not require a hazardous classification unless the location contains a concentration over
25 percent of the material’s lower flammable limit (LFL).
Commentary Table 500.1 Selected Chemicals
Chemical
Acetaldehyde
Acetic Acid
Acetic Acid-tert-Butyl
Ester
Acetic Anhydride
Acetone
Acetone Cyanohydrin
Acetonitrile
Acetylene
Acrolein (Inhibited)
Acrylic Acid
Acrylonitrile
Adiponitrile
Allyl Alcohol
Allyl Chloride
Allyl Glycidyl Ether
Alpha-Methyl Styrene
n-Amyl Acetate
sec-Amyl Acetate
Ammonia
Aniline
Benzene
CAS
No.
75-07-0
64-19-7
540-885
108-247
67-64-1
75-86-5
75-05-8
74-86-2
107-028
79-10-7
107-131
111-693
107-186
107-051
106-923
98-83-9
628-637
626-380
766441-7
62-53-3
71-43-2
Class I
Division
Group
Cd
Dd
D
Typea
D
II
49
Dd
D
D
Ad
B(C)d
I
IIIA
I
GAS
I
–20
74
6
D
Dd
II
I
D
Vapor
Pressureb
(mm Hg)
874.9
15.6
40.6
Class I
Zone
Groupc
IIA
IIA
1.7
60.0
19.9
9.8
Vapor
Density
(Air = 1)
1.5
2.1
4.0
316
2.7
10.3
3.5
4.9
IIA
465
688
524
305
235
2.5
2.2
3.0
2.5
2.8
12.8
12.0
16.0
100
31.0
2.0
2.9
1.4
0.9
1.9
230.7
0.3
91.1
36600
274.1
IIA
54
0
438
481
2.4
3
8.0
17
2.5
1.8
4.3
108.5
IIB
IIB
IIIA
93
550
1.0
0.002
Cd
I
22
378
2.5
18.0
2.0
25.4
IIB
D
I
–32
485
2.9
11.1
2.6
366
IIA
B(C)e
II
57
D
D
II
I
25
574
360
2.7
4.2
IIA
D
I
23
Dd,f
GAS
D
Dd
IIIA
I
I
II
II
Flash
Point
(ºC)
–38
39
70
–11
AIT
(ºC)
%LFL
%UFL
175
426
4.0
IIA
IIC
IIB
MIE
(mJ)
MIC
Ratio
MESG
(mm)
0.37
0.98
2.67
0.92
1.76
1.23
1.15
0.017
0.13
0.16
1.00
1.02
0.28
1.50
0.25
0.78
0.86
0.87
0.84
1.33
1.17
3.9
0.8
1.1
11.0
7.5
4.1
4.5
1.1
7.5
4.5
651
15
28
0.6
7498.0
IIA
680
6.85
3.17
615
498
1.2
1.2
8.3
7.8
3.2
2.8
0.7
94.8
IIA
IIA
0.20
1.00
0.99
1.02
IIA
Benzyl Chloride
Bromopropyne
n-Butane
1,3-Butadiene
1-Butanol
Butyl alcohol (s) (butanol2)
Butylamine
Butylene
n-Butyraldehyde
n-Butyl Acetate
sec-Butyl Acetate
tert-Butyl Acetate
n-Butyl Acrylate
(Inhibited)
n-Butyl Glycidyl Ether
n-Butyl Formal
Butyl Mercaptan
Butyl-2-Propenoate
para tert-Butyl Toluene
n-Butyric Acid
98-87-3
106-967
358347-9
106-990
71-36-3
78-92-2
109-739
2516767-3
123-728
123-864
105-464
540-885
141-322
242608-6
110-623
109-795
141-322
98-51-1
107-926
D
D
IIIA
I
585
324
1.1
3.0
Dd,g
GAS
288
1.9
8.5
2.0
IIA
0.25
0.94
1.07
B(D)d,e
GAS
420
2.0
11.5
1.9
IIB
0.13
0.76
0.79
Dd
Dd
I
I
36
23.8
343
405
1.4
1.7
11.2
9.8
2.6
2.6
7.0
IIA
IIA
D
GAS
–12
312
1.7
9.8
2.5
92.9
IIA
D
I
385
1.6
10.0
1.9
2214.6
IIA
0.94
Cd
I
–12
218
1.9
12.5
2.5
112.2
IIA
0.92
Dd
I
–2
421
1.7
7.6
4.0
11.5
IIA
D
II
28
1.7
9.8
4.0
22.2
D
II
1.7
9.8
4.0
40.6
D
II
1.7
9.9
4.4
5.5
B(C)e
II
C
IIIA
C
I
2
D
II
49
D
Dd
IIIA
IIIA
72
10
49
293
4.4
0.5
34.3
443
3.1
46.4
1.7
9.9
4.4
5.5
2.0
10.0
3.0
0.8
IIB
0.91
1.13
1.08
1.04
0.88
Carbon Disulfide
Carbon Monoxide
Chloroacetaldehyde
Chlorobenzene
1-Chloro-1-Nitropropane
Chloroprene
Cresol
Crotonaldehyde
Cumene
Cyclohexane
Cyclohexanol
Cyclohexanone
Cyclohexene
Cyclopropane
p-Cymene
Decene
n-Decaldehyde
n-Decanol
Decyl Alcohol
75-15-0
630-080
107-200
108-907
242566-3
126-998
131977-3
417030-3
98-82-8
110-827
108-930
108-941
110-838
75-19-4
99-87-6
872-059
112-312
112-301
112-301
d,h
Cd
I
GAS
–30
90
609
1.3
12.5
50.0
74
2.6
0.97
358.8
IIC
IIB
0.009
0.39
0.20
0.54
C
IIIA
88
D
I
29
C
IIIA
D
GAS
–20
D
IIIA
81
559
1.1
Cd
I
13
232
2.1
15.5
2.4
33.1
IIB
0.81
D
D
I
I
36
–17
424
245
0.9
1.3
6.5
8.0
4.1
2.9
4.6
98.8
IIA
IIA
1.05
0.94
D
IIIA
68
300
3.5
0.7
IIA
D
II
44
420
1.1
3.4
4.3
IIA
D
I
–6
244
1.2
2.8
89.4
IIA
Dd
D
D
I
II
II
47
503
436
235
2.4
0.7
1.5
4.6
4.8
5430
1.5
1.7
IIA
IIA
C
IIIA
D
IIIA
82
288
5.3
0.008
D
IIIA
82
288
5.3
0.008
63.1
593
1.3
9.6
3.9
4.0
20.0
3.0
11.9
3.7
9.4
10.4
5.6
0.09
0.22
1.0
0.98
0.97
0.17
0.84
0.91
Diacetone Alcohol
Di-Isobutylene
Di-Isobutyl Ketone
o-Dichlorobenzene
1,4-Dichloro-2,3
Epoxybutane
1,1-Dichloroethane
1,2-Dichloroethylene
1,1-Dichloro-1Nitroethane
1,3-Dichloropropene
Dicyclopentadiene
Diethylamine
Diethylaminoethanol
Diethyl Benzene
Diethyl Ether (Ethyl Ether)
Diethylene Glycol
Monobutyl Ether
Diethylene Glycol
Monomethyl Ether
n-n-Dimethyl Aniline
Dimethyl Formamide
Dimethyl Sulfate
123-422
2516770-8
108-838
955-501
358347-9
130021-6
156-592
594-729
1006102-6
77-73-6
109-879
100-378
2534017-4
60-29-7
112-345
111-773
121-697
68-12-2
77-78-1
D
IIIA
64
603
1.8
6.9
4.0
1.4
Dd
I
2
391
0.8
4.8
3.8
D
II
60
396
0.8
7.1
4.9
D
IIIA
66
647
2.2
9.2
5.1
IIA
Dd
I
1.9
8.5
2.0
IIA
D
I
438
6.2
16.0
3.4
227
IIA
1.82
D
I
97
460
5.6
12.8
3.4
204
IIA
3.91
C
IIIA
76
D
I
35
C
Cd
I
I
32
–28
503
312
2.8
IIA
IIA
0.91
1.15
C
IIIA
60
320
4.0
1.6
IIA
D
II
57
395
4.6
Cd
C
I
IIIA
–45
78
160
228
538
0.02
IIB
C
IIIA
93
241
C
IIIA
63
371
1.0
D
D
II
IIIA
58
83
455
188
2.2
0.96
1.7
0.25
0.98
1.07
5.0
5.3
14.5
3.8
1.8
10.1
2.5
1.9
0.9
36
24.6
2.6
5.6
0.19
0.88
0.83
0.2
15.2
4.2
0.7
2.5
4.4
4.1
0.7
IIA
1.08
Dimethylamine
2,2-Dimethylbutane
2,3-Dimethylbutane
3,3-Dimethylheptane
2,3-Dimethylhexane
2,3-Dimethylpentane
Di-N-Propylamine
1,4-Dioxane
Dipentene
Dipropylene Glycol
Methyl Ether
Diisopropylamine
Dodecene
Epichlorohydrin
Ethane
Ethanol
Ethylamine
Ethylene
Ethylenediamine
Ethylenimine
Ethylene Chlorohydrin
124-403
75-83-2
78-29-8
107126-7
3139454-4
107-835
142-847
123-911
138-863
3459094-8
108-189
684215-5
313264-7
74-84-0
64-17-5
75-04-7
74-85-1
107-153
151-564
107-073
C
GAS
400
Dg
Dg
Dg
I
I
I
Dg
I
438
Dg
I
335
211.7
C
I
17
299
27.1
IIA
Cd
I
12
180
2.0
22.0
3.0
38.2
IIB
D
II
45
237
0.7
6.1
4.7
C
IIIA
85
1.1
3.0
5.1
C
GAS
–6
316
1.1
7.1
3.5
D
IIIA
100
255
Cd
I
33
411
3.8
21.0
3.2
Dd
Dd
Dd
Cd
Dd
GAS
I
I
GAS
I
–29
13
–18
33
472
363
385
490
385
3.0
3.3
3.5
2.7
2.5
12.5
19.0
14.0
36.0
12.0
1.0
1.6
1.6
1.0
2.1
Cd
I
–11
320
3.3
54.8
1.5
211
D
IIIA
59
425
4.9
15.9
2.8
7.2
–48
2.8
14.4
1.6
405
396
325
IIA
319.3
10.8
0.95
0.19
0.70
IIA
1.18
IIA
1.02
0.5
13.0
59.5
1048
IIA
IIA
IIB
0.24
2.4
0.070
12.5
0.48
0.82
0.88
0.91
0.89
0.53
0.65
Ethylene Dichloride
Ethylene Glycol
Monoethyl Ether Acetate
Ethylene Glycol
Monobutyl Ether Acetate
Ethylene Glycol
Monobutyl Ether
Ethylene Glycol
Monoethyl Ether
Ethylene Glycol
Monomethyl Ether
Ethylene Oxide
2-Ethylhexaldehyde
2-Ethylhexanol
2-Ethylhexyl Acrylate
Ethyl Acetate
Ethyl Acrylate (Inhibited)
Ethyl Alcohol
Ethyl Sec-Amyl Ketone
Ethyl Benzene
Ethyl Butanol
Ethyl Butyl Ketone
Ethyl Chloride
Ethyl Formate
Ethyl Mercaptan
107-062
111-159
112-072
111-762
110-805
109-864
75-21-8
123-057
104-767
103-093
141-786
140-885
64-17-5
541-855
100-414
97-95-0
106-354
75-00-3
109-944
75-08-1
Dd
I
13
413
6.2
16.0
3.4
79.7
C
II
47
379
1.7
4.7
2.3
C
IIIA
340
0.9
8.5
C
IIIA
238
1.1
12.7
4.1
1.0
C
II
235
1.7
15.6
3.0
5.4
0.84
D
II
285
1.8
14.0
2.6
9.2
0.85
B(C)d,e
C
I
II
–20
52
429
191
3
0.8
100
7.2
1.5
4.4
1314
1.9
D
IIIA
81
0.9
9.7
4.5
0.2
D
IIIA
88
252
Dd
I
–4
427
2.0
11.5
3.0
Dd
I
9
372
1.4
14.0
Dd
D
I
II
13
59
363
3.3
D
I
15
432
D
D
II
II
57
46
D
D
GAS
GAS
–50
–20
Cd
I
–18
IIA
0.53
0.97
0.9
IIB
0.065
93.2
IIA
0.46
3.5
37.5
IIA
19.0
1.6
59.5
IIA
0.8
6.7
3.7
9.6
1.2
7.7
3.5
4.0
1.5
3.6
519
455
3.8
2.8
15.4
16.0
2.2
2.6
300
2.8
18.0
2.1
0.47
0.59
0.3
0.99
0.86
0.88
IIA
527.4
IIB
0.89
0.94
0.90
0.90
n-Ethyl Morpholine
2-Ethyl-3-Propyl Acrolein
Ethyl Silicate
Formaldehyde (Gas)
Formic Acid
Fuel Oil 1
100-743
645-625
78-10-4
50-00-0
64-18-6
800820-6
C
I
32
4.0
C
IIIA
68
4.4
D
B
D
D
C
C
Dd
II
GAS
II
II or
IIIAk
II or
IIIAk
IIIA or
IIIBk
IIIA
IIIA
I
50
38–
72k
52–
96k
66–
132k
60
75
–46
Dd
I
Dg
73
57.0
5.0
316
490
280
2.1
1.8
1.4
19.3
16.3
7.6
3.3
3.4
3.0
2.3
0.6
–4
204
1.0
6.7
3.5
45.5
I
–1
204
Dd,g
I
–23
225
D
IIIA
63
D
I
35
424
1.2
8.0
D
I
–26
245
1.2
6.9
D
II
45
C
II
38
Bd
GAS
Fuel Oil 6
Furfural
Furfuryl Alcohol
Gasoline
n-Heptane
n-Heptene
n-Hexane
Hexanol
2-Hexanone
Hexene
sec-Hexyl Acetate
Hydrazine
Hydrogen
98-01-1
98-00-0
800661-9
142-825
8162404-6
110-543
111-273
591-786
592-416
108-849
302-012
133374-0
7.2
1.0
1.6
7
18.0
0.7
Fuel Oil 2
430
434
210
42.7
IIB
IIA
0.57
1.86
257
0.94
IIA
0.24
0.88
3.4
1.1
7.5
0.91
0.97
3.0
152
IIA
3.5
0.8
IIA
3.5
10.6
0.24
0.88
0.93
0.98
186
5.0
23
500
4
98.0
1.1
75
0.1
14.4
IIC
0.019
0.25
0.28
Hydrogen Cyanide
Hydrogen Selenide
Hydrogen Sulfide
Isoamyl Acetate
Isoamyl Alcohol
Isobutane
Isobutyl Acetate
Isobutyl Acrylate
Isobutyl Alcohol
Isobutyraldehyde
Isodecaldehyde
Isohexane
Isopentane
Isooctyl Aldehyde
Isophorone
Isoprene
Isopropyl Acetate
Isopropyl Ether
Isopropyl Glycidyl Ether
Isopropylamine
Kerosene
74-90-8
778307-5
778306-4
123-922
123-513
75-28-5
110-190
106-638
78-83-1
78-84-2
112-312
107-835
78-78-4
123-057
78-59-1
78-79-5
108-214
108-203
401614-2
75-31-0
800820-6
Cd
C
GAS
I
Cd
GAS
D
I
D
–18
538
5.6
40.0
0.9
IIB
260
4.0
44.0
1.2
25
360
1.0
7.5
4.5
6.1
II
43
350
1.2
9.0
3.0
3.2
Dg
Dd
GAS
I
18
460
421
1.8
2.4
8.4
10.5
2.0
4.0
17.8
D
I
4.4
7.1
Dd
C
C
I
GAS
IIIA
2.5
2.5
5.4
10.5
427
–40
–40
Dg
Dg
C
II
D
Dd
D
I
I
Dd
I
C
I
D
D
GAS
II
0.80
7793
416
196
1.2
1.6
10.9
10.6
IIB
0.068
0.90
IIA
1.02
IIA
0.95
IIA
IIA
0.92
IIA
1.00
0.98
0.92
0.09
264
211.7
420
197
688.6
1.9
84
–54
460
220
460
0.8
1.5
1.8
3.8
8.9
8.0
4.8
2.4
3.5
0.4
550.6
60.4
–28
443
1.4
7.9
3.5
148.7
–26
72
402
210
2.3
0.7
10.4
5.0
2.0
IIA
1.14
2.0
IIA
0.94
Liquefied Petroleum Gas
Mesityl Oxide
Methane
Methanol
Methyl Acetate
Methyl Acrylate
Methyl Alcohol
Methyl Amyl Alcohol
Methyl Chloride
Methyl Ether
Methyl Ethyl Ketone
Methyl Formal
Methyl Formate
2-Methylhexane
Methyl Isobutyl Ketone
Methyl Isocyanate
Methyl Mercaptan
Methyl Methacrylate
Methyl N-Amyl Ketone
Methyl Tertiary Butyl
Ether
2-Methyloctane
2-Methylpropane
Methyl-1-Propanol
6847685-7
141-979
74-82-8
67-56-1
79-20-9
96-33-3
67-56-1
108-112
74-87-3
115-106
78-93-3
534-156
107-313
3139454-4
141-797
624-839
74-93-1
80-62-6
110-430
163404-4
322161-2
75-28-5
78-83-1
D
I
Dd
I
Dd
Dd
D
D
Dd
D
GAS
I
GAS
GAS
I
II
D
Cd
GAS
GAS
Dd
Cd
405
31
344
1.4
7.2
3.4
12
–10
23
600
385
454
468
385
5
6.0
3.1
2.8
6.0
1.0
15
36.0
16.0
25.0
36
5.5
0.6
1.1
2.6
3.0
1.1
3.5
–46
–41
632
350
8.1
3.4
17.4
27.0
1.7
1.6
I
I
–6
1
404
238
1.4
11.4
2.5
3.1
D
GAS
–19
449
4.5
23.0
2.1
Dg
I
Dd
I
31
440
1.2
8.0
3.5
D
GAS
–15
534
5.3
26.0
2.0
C
D
D
GAS
I
II
–18
10
49
422
393
3.9
1.7
1.1
21.8
8.2
7.9
1.7
3.6
3.9
37.2
3.8
D
I
–80
435
1.6
8.4
0.2
250.1
Dg
Dd
I
I
41
47.6
126.3
126.3
5.3
IIA
IIA
IIA
IIB
IIA
IIA
0.28
0.14
IIA
IIB
92.4
IIB
0.53
1.00
0.82
1.08
0.98
1.12
0.92
0.99
0.85
0.91
1.01
0.85
1.00
0.84
0.92
0.84
IIA
0.94
IIA
1.21
IIA
0.95
IIA
0.98
280
–40
11
220
6.3
460
416
2639
10.1
1.2
10.9
2.5
Methyl-2-Propanol
2-Methyl-5-Ethyl Pyridine
Methylacetylene
MethylacetylenePropadiene
Methylal
Methylamine
2-Methylbutane
Methylcyclohexane
Methylcyclohexanol
2-Methycyclohexanone
2-Methylheptane
3-Methylhexane
3-Methylpentane
2-Methylpropane
2-Methyl-1-Propanol
2-Methyl-2-Propanol
2-Methyloctane
3-Methyloctane
4-Methyloctane
Monoethanolamine
Monoisopropanolamine
Monomethyl Aniline
Monomethyl Hydrazine
75-65-0
104-905
74-99-7
2784630-6
109-875
74-89-5
78-78-4
208-872
2563042-3
583-608
589-344
94-14-0
75-28-5
78-83-1
75-65-0
221632-2
221633-3
221634-4
141-435
78-96-6
100-618
60-34-4
Dd
D
I
Cd
C
I
I
C
I
D
Dg
D
GAS
I
D
D
10
74
360
2.4
1.1
8.0
6.6
1.7
42.2
1.4
4306
–18
237
1.6
17.6
2.6
–56
–4
430
420
250
4.9
1.4
1.2
20.7
8.3
6.7
1.0
2.6
3.4
68
296
420
280
Dg
Dg
Dd
Dd
Dg
278
460
223
478
220
IIA
1.10
398
688.6
0.27
–40
61.5
1.2
2.4
10.9
8.0
2.5
2.6
2639
10.5
42.2
Dg
220
6.3
Dg
225
6.8
D
85
410
2.1
0.4
D
C
77
374
482
2.6
1.1
0.5
23
194
I
0.74
3.9
Dg
Dg
C
0.11
IIB
3.9
II
I
I
I
2.6
4.2
2.5
92.0
1.6
IIA
Morpholine
Naphtha (Coal Tar)
Naphtha (Petroleum)
Neopentane
Nitrobenzene
Nitroethane
Nitromethane
1-Nitropropane
2-Nitropropane
n-Nonane
Nonene
Nonyl Alcohol
n-Octane
Octene
n-Octyl Alcohol
n-Pentane
1-Pentanol
2-Pentanone
1-Pentene
2-Pentene
110-918
803030-6
803030-6
463-821
98-95-3
79-24-3
75-52-5
108-032
79-46-9
111-842
2721495-8
143-088
111-659
2537783-7
111-875
109-660
71-41-0
107-879
109-671
109-682
Cd
II
35
310
1.4
11.2
D
II
42
277
Dd,i
I
42
288
1.1
5.9
2.5
Dg
–65
450
1.4
8.3
2.6
1286
D
C
C
C
I
I
I
88
28
35
34
482
414
418
421
1.8
3.4
7.3
2.2
4.3
2.6
2.1
3.1
0.3
20.7
36.1
10.1
IIA
IIB
IIA
IIB
Cd
Dg
I
I
28
31
428
205
2.6
0.8
3.1
4.4
17.1
4.4
IIA
D
I
10.1
IIA
0.95
IIA
11.0
2.9
0.8
D
3.0
IIA
0.92
0.94
0.87
1.17
0.84
4.4
0.8
6.1
5.0
0.02
IIA
6.5
3.9
14.0
IIA
0.94
4.5
0.08
IIA
1.05
Dd,g
I
13
206
1.0
D
I
8
230
0.9
3.9
D
Dd,g
I
–40
243
1.5
7.8
2.5
513
IIA
Dd
D
I
I
33
7
300
452
1.2
1.5
10.0
8.2
3.0
3.0
2.5
35.6
IIA
IIA
D
I
–18
275
1.5
8.7
2.4
639.7
D
I
–18
2.4
0.28
0.97
0.93
1.30
0.99
2-Pentyl Acetate
Phenylhydrazine
Process Gas > 30% H2
Propane
1-Propanol
2-Propanol
Propiolactone
Propionaldehyde
Propionic Acid
Propionic Anhydride
n-Propyl Acetate
n-Propyl Ether
Propyl Nitrate
Propylene
Propylene Dichloride
Propylene Oxide
Pyridine
Styrene
Tetrahydrofuran
Tetrahydronaphthalene
Tetramethyl Lead
626-380
100-630
133374-0
74-98-6
71-23-8
67-63-0
57-57-8
123-386
79-09-4
123-626
109-604
111-433
627-134
115-071
78-87-5
75-56-9
110-861
100-425
109-999
119-642
75-74-1
D
I
D
23
1.1
7.5
89
Bj
GAS
Dd
Dd
Dd
D
C
GAS
I
I
4.5
3.7
0.03
520
4.0
75.0
0.1
15
12
450
413
399
9.5
13.7
12.7
I
–9
207
2.1
2.2
2.0
2.9
2.6
17.0
1.6
2.1
2.1
2.5
2.0
20.7
45.4
2.2
318.5
D
D
II
54
74
466
285
2.9
1.3
12.1
9.5
2.5
4.5
D
I
14
450
1.7
8.0
Cd
I
21
215
1.3
7.0
Bd
I
20
175
2.0
100.0
Dd
GAS
460
2.4
10.3
1.5
D
B(C)d,e
Dd
I
I
I
16
–37
20
557
449
482
3.4
2.3
1.8
14.5
36.0
12.4
3.9
2.0
2.7
Dd
I
31
490
0.9
6.8
Cd
I
–14
321
2.0
D
IIIA
385
0.8
C
II
38
IIA
IIA
IIA
0.019
0.45
0.25
0.82
0.65
0.97
0.89
1.00
IIB
0.86
3.7
1.4
IIA
1.10
3.5
33.4
IIA
1.05
3.5
62.3
IIA
0.28
0.91
51.7
534.4
20.8
IIA
IIB
IIA
0.13
1.32
0.70
3.6
6.1
IIA
11.8
2.5
161.6
IIB
5.0
4.6
0.4
9.2
1.21
0.54
0.87
Toluene
n-Tridecene
Triethylamine
Triethylbenzene
2,2,3-Trimethylbutane
2,2,4-Trimethylbutane
2,2,3-Trimethylpentane
2,2,4-Trimethylpentane
2,3,3-Trimethylpentane
Tripropylamine
Turpentine
n-Undecene
Unsymmetrical Dimethyl
Hydrazine
Valeraldehyde
Vinyl Acetate
Vinyl Chloride
Vinyl Toluene
Vinylidene Chloride
Xylene
Xylidine
108-883
243756-1
121-448
2534018-5
102-692
800664-2
2876127-5
57-14-7
110-623
108-054
75-01-4
2501315-4
75-35-4
133020-7
121-697
Dd
I
D
IIIA
Cd
I
D
4
480
1.1
7.1
3.1
28.53
6.4
593.4
8.0
3.5
68.5
56.0
5.6
0.6
–9
249
1.2
83
Dg
Dg
Dg
Dg
Dg
D
442
407
396
415
425
II
41
D
I
35
D
IIIA
Cd
I
–15
249
C
I
280
222
Dd
I
–6
402
2.6
Dd
D
GAS
–78
52
472
494
D
Dd
I
I
25
C
IIIA
63
4.9
253
0.8
0.24
IIA
0.75
1.05
IIA
1.04
IIA
1.13
4.8
0.7
2.0
1.5
IIA
5.5
95.0
1.9
IIB
3.0
34.3
13.4
3.0
113.4
3.6
0.8
33.0
11.0
2.2
4.1
570
464
6.5
0.9
15.5
7.0
3.4
3.7
599.4
371
1.0
4.2
0.7
IIA
0.70
IIA
a
Type is used to designate if the material is a gas, flammable liquid, or combustible liquid. (See 4.2.6 and 4.2.7 of NFPA 497.)
b
Vapor pressure reflected in units of mm Hg at 25ºC (77ºF) unless stated otherwise.
IIA
IIA
0.94
0.96
0.2
3.91
1.09
c Class I, Zone Groups are based on 1996 IEC TR3 60079-20, Electrical apparatus for explosive gas atmospheres — Part 20: Data for flammable gases and vapors,
relating to the use of electrical apparatus, which contains additional data on MESG and group classifications.
d
Material has been classified by test.
e
Where all conduit runs into explosionproof equipment are provided with explosionproof seals installed within 450 mm (18 in.) of the enclosure, equipment for
the group classification shown in parentheses is permitted.
f
For classification of areas involving ammonia, see ASHRAE 15, Safety Code for Mechanical Refrigeration, and ANSI/CGA G2.1, Safety Requirements for the
Storage and Handling of Anhydrous Ammonia.
g
Commercial grades of aliphatic hydrocarbon solvents are mixtures of several isomers of the same chemical formula (or molecular weight). The autoignition
temperatures of the individual isomers are significantly different. The electrical equipment should be suitable for the AIT of the solvent mixture. (See A.4.4.2 of
NFPA 497.)
h
Certain chemicals have characteristics that require safeguards beyond those required for any of the above groups. Carbon disulfide is one of these chemicals
because of its low autoignition temperature and the small joint clearance necessary to arrest its flame propagation.
I
Petroleum naphtha is a saturated hydrocarbon mixture whose boiling range is 20ºC to 135ºC (68ºF to 275ºF). It is also known as benzine, ligroin, petroleum
ether, and naphtha.
j
Fuel and process gas mixtures found by test not to present hazards similar to those of hydrogen may be grouped based on the test results.
k
Liquid type and flash point vary due to regional blending differences.
Source: NFPA 497-2008, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical
Installations in Chemical Process Areas, Table 4.4.2