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Substance

LFL/LEL in %

by volume of air

UFL/UEL in %

by volume of air

NFPA Class

Flash point

Minimum ignition energy in mJ

Expressed at percent by volume in air
(Note that for many chemicals it
takes the least amount of
ignition energy halfway between
the LEL and UEL.)
[2]

Auto ignition
temperature

1,1-Dichloroethane

6

11

IB

14 C

1,1-Dichloroethene

6.5

15.5

IA

−10 C Flammable gas

1,1-Difluoroethane

3.7

18

IA

−81.1 C[22]

1,1-Difluoroethylene

5.5

21.3

−126.1 C[23]

1,1-Dimethylhydrazine

IB

1,2-Dichloroethane

6

16

IB

13 C

413 C

1,3-Butadiene

2.0

12

IA

−85 C

0.13 @ 5.2%

1,4-Dioxane

2

22

IB

12 C

1-Chloro-1,1-difluoroethane

6.2

17.9

IA

−65 C Flammable gas

2-Ethoxyethanol

3

18

43 C

2-Ethoxyethyl acetate

2

8

56 C

2-Mercaptoethanol

IIIA

Acetaldehyde

4.0

57.0

IA

−39 C

0.37

175 C

Acetic acid (glacial)

4

19.9

II

39 C to 43 C

463 C

Acetic anhydride

II

54 C

Acetone

2.63

12.813

IB

−17 C

1.15 @ 4.5%

465 C, 485 C[3]

Acetonitrile

IB

2 C

524 C

Acetyl chloride

7.3

19

IB

5 C

390 C

Acetylene

2.5

100[4]

IA

Flammable gas

0.017 @ 8.5% (in pure oxygen 0.0002 @ 40%)

305 C

Acrolein

2.8

31

IB

−26 C

0.13

Acrylonitrile

3.0

17.0

IB

0 C

0.16 @ 9.0%

Allyl chloride

2.9

11.1

IB

−32 C

0.77

Ammonia

15

28

IIIB

11 C

680

651 C

Arsine

4.55.1[5]

78

IA

Flammable gas

Benzene

1.2

7.8

IB

−11 C

0.2 @ 4.7%

560 C

Butanen-butane

1.6

8.4

IA

−60 C

0.25 @ 4.7%

420500 C

Butyl alcohol, butanol

1

11

IC

29 C

Butyl methyl ketone2-hexanone

1[7]

8

IC

25 C

423 C

Butylene1-butylene, 1-butene

1.98[5]

9.65

IA

−80 C

Carbon disulfide

1.0

50.0

IB

−30 C

0.009 @ 7.8%

90 C

Carbon monoxide

12[5]

75

IA

−191 C Flammable gas

609 C

Chlorine monoxide

IA

Flammable gas

Cyanogen

6.06.6[8]

3242.6

IA

Flammable gas

Cyclobutane

1.8

11.1

IA

−63.9 C[9]

426.7 C

Cyclohexane

1.3

7.88

IB

−18 C to -20 C[10]

0.22 @ 3.8%

245 C

Cyclohexanol

1

9

IIIA

68 C

300 C

Cyclohexanone

11.1

99.4

II

43.944 C

420 C[11]

Cyclopentadiene[12]

IB

0 C

0.67

640 C

Cyclopentane

1.52

9.4

IB

−37 to −38.9 C[13][14]

0.54

361 C

Cyclopropane

2.4

10.4

IA

−94.4 C[15]

0.17 @ 6.3%

498 C

Decane

0.8

5.4

II

46.1 C

210 C

Diborane

0.8

88

IA

−90 C Flammable gas[16]

38 C

Dichlorofluoromethane

54.7

Non flammable,[18] -36.1 C[19]

552 C

Dichloromethane, methylene chloride

16

66

Non flammable

Dichlorosilane

44.7

96

IA

−28 C

0.015

Diesel fuel

0.6

7.5

IIIA

>62 C (143 F)

210 C

Diethanolamine

2

13

IB

169 C

Diethyl disulfide

1.2

II

38.9 C[20]

Diethyl ether

1.92

3648

IA

−45 C

0.19 @ 5.1%

160170 C

Diethyl sulfide

IB

−10 C[21]

Diethylamine

1.8

10.1

IB

−23 to −26 C

312 C

Diisobutyl ketone

1

6

49 C

Diisopropyl ether

1

21

IB

−28 C

Dimethyl sulfide

IA

−49 C

Dimethyl sulfoxide

2.63

42

IIIB

8895 C

215 C

Dimethylamine

2.8

14.4

IA

Flammable gas

Epichlorohydrin

4

21

31 C

Ethane

3[5]

1212.4

IA

Flammable gas -135 C

515 C

Ethanol, ethyl alcohol

33.3

19

IB

12.8 C (55 F)

365 C

Ethyl acetate

2

12

IA

−4 C

460 C

Ethyl chloride

3.8[5]

15.4

IA

−50 C

Ethyl mercaptan

IA

Ethylamine

3.5

14

IA

−17 C

Ethylbenzene

1.0

7.1

1520 C

Ethylene

2.7

36

IA

0.07

490 C

Ethylene glycol

3

22

111 C

Ethylene oxide

3

100

IA

−20 C

Fuel oil No.1

0.7[5]

5

Furan

2

14

IA

−36 C

Gasoline (100 octane)

1.4

7.6

IB

< −40 C (−40 F)

246280 C

Glycerol

3

19

199 C

Heptane, n-heptane

1.05

6.7

−4 C

0.24 @ 3.4%

204215 C

Hexane, n-hexane

1.1

7.5

−22 C

0.24 @ 3.8%

225 C, 233 C[3]

Hydrogen

4/18.3[24]

75/59

IA

Flammable gas

0.016 @ 28% (in pure oxygen 0.0012)

500571 C

Hydrogen sulfide

4.3

46

IA

Flammable gas

0.068

iso-Octane

0.79

5.94

iso-Pentane

1.32[5]

9.16

IA

420 C

Isobutane

1.8[5]

9.6

IA

Flammable gas

462 C

Isobutyl alcohol

2

11

28 C

Isophorone

1

4

84 C

Isopropyl alcohol, isopropanol

2[5]

12

IB

12 C

398399 C; 425 C[3]

Isopropyl chloride

IA

Kerosene Jet A-1

0.60.7

4.95

II

>38 C (100 F) as jet fuel

210 C

Lithium hydride

IA

m-Xylene

1.1[3]

7

IC

25 C

525 C

Methane (natural gas)

5.0

15

IA

Flammable gas

0.21 @ 8.5%

580 C

Methyl acetate

3

16

−10 C

Methyl alcohol, methanol

66.7[5]

36

IB

11 C

385 C; 455 C[3]

Methyl chloride

10.7[5]

17.4

IA

−46 C

Methyl ether

IA

−41 C

Methyl ethyl ether

IA

Methyl ethyl ketone

1.8[5]

10

IB

−6 C

505515 C[3]

Methyl formate

IA

Methyl mercaptan

3.9

21.8

IA

−53 C

Methylamine

IA

8 C

Mineral spirits

0.7[3]

6.5

3843 C

258 C

Morpholine

1.8

10.8

IC

3137.7 C

310 C

n-Butanol

1.4[3]

11.2

IC

35 C

340 C

n-Butyl acetate, butyl acetate

11.7[3]

815

IB

24 C

370 C

n-Butyl chloride, 1-chlorobutane

1.8

10.1

IB

−6 C

1.24

n-Butyl mercaptan

1.4[6]

10.2

IB

2 C

225 C

n-Pentane

1.4

7.8

IA

0.28 @ 3.3%

Naphthalene

0.9[5]

5.9

IIIA

7987 C

540 C

Neohexane

1.19[5]

7.58

−29 C

425 C

Nickel tetracarbonyl

2

34

4 C

60 C

Nitrobenzene

2

9

IIIA

88 C

Nitromethane

7.3

22.2

35 C

379 C

o-Dichlorobenzene, 1,2-dichlorobenzene

2[17]

9

IIIA

65 C

648 C

o-Xylene

IC

17 C

Octane

1

7

13 C

p-Xylene

1.0

6.0

IC

27.2 C

530 C

Pentane

1.5

7.8

IA

−40 to −49 C

as 2-Pentane 0.18 @ 4.4%

260 C

Phosphine

IA

Propane

2.1

9.510.1

IA

Flammable gas

0.25 @ 5.2% (in pure oxygen 0.0021)

480 C

Propyl acetate

2

8

13 C

Propylene

2.0

11.1

IA

−108 C

0.28

458 C

Propylene oxide

2.9

36

IA

Pyridine

2

12

20 C

Silane

1.5[5]

98

IA

<21 C

Styrene

1.1

6.1

IB

3132.2 C

490 C

Tetrafluoroethylene

IA

Tetrahydrofuran

2

12

IB

−14 C

321 C

Toluene

1.21.27

6.757.1

IB

4.4 C

0.24 @ 4.1%

480 C; 535 C[3]

Triethylborane

−20 C

−20 C

Trimethylamine

IA

Flammable gas

Trinitrobenzene

IA

Turpentine

0.8[25]

IC

35 C

Vegetable oil

IIIB

327 C (620 F)

Vinyl acetate

2.6

13.4

−8 C

Vinyl chloride

3.6

33

Xylenes

0.91.0

6.77.0

IC

2732 C

0.2