# Flammability limit

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Burning within well-defined lower and upper bounds

**Flammability limits** or **explosive limits** are the ranges of [fuel](/source/Fuel) concentrations in relation to oxygen from the air. Combustion can range in violence from [deflagration](/source/Deflagration) through [detonation](/source/Detonation).

Limits vary with temperature and pressure, but are normally expressed in terms of volume percentage at 25 °C and atmospheric pressure. These limits are relevant both in producing and optimising explosion or combustion, as in an engine, or to preventing it, as in uncontrolled explosions of build-ups of combustible gas or dust. Attaining the best combustible or explosive mixture of a fuel and air (the [stoichiometric](/source/Stoichiometric) proportion) is important in [internal combustion engines](/source/Internal_combustion_engine) such as [gasoline](/source/Petrol_engine) or [diesel engines](/source/Diesel_engine).

The standard reference work is still that elaborated by [Michael George Zabetakis](/source/Michael_George_Zabetakis), a [fire safety engineering](/source/Fire_safety_engineering) specialist, using an apparatus developed by the [United States Bureau of Mines](/source/United_States_Bureau_of_Mines).

## Violence of combustion

Combustion can vary in degree of violence. A [deflagration](/source/Deflagration) is a propagation of a combustion zone at a velocity less than the speed of sound in the unreacted medium. A [detonation](/source/Detonation) is a propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium. An [explosion](/source/Explosion) is the bursting or rupture of an enclosure or container due to the development of internal pressure from a deflagration or detonation as defined in [NFPA](/source/National_Fire_Protection_Association) 69.

## Limits

Any mixture of combustibles has specific lower and upper flammability limits. These limits are a function of the [pressure](/source/Pressure), [temperature](/source/Temperature) and [composition](/source/Chemical_composition). These limits are often shown in [flammability diagrams](/source/Flammability_diagram) for which an example can be found in the work by Bee and Börner.[1]

### Lower flammability limit

**[Lower flammability limit](/source/Lower_flammable_limit)** (LFL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower explosive level (LEL). At a concentration in air lower than the LFL, gas mixtures are "too lean" to burn. Methane gas has an LFL of 4.4%.[2] If the atmosphere has less than 4.4% methane, an explosion cannot occur even if a source of ignition is present. From the health and safety perspective, the LEL concentration is considered to be [Immediately Dangerous to Life or Health (IDLH)](/source/Immediately_dangerous_to_life_or_health), where a more stringent exposure limit does not exist for the flammable gas.[3]

Percentage reading on combustible air monitors should not be confused with the LFL concentrations. [Explosimeters](/source/Explosimeter) designed and calibrated to a specific gas may show the relative concentration of the atmosphere to the LFL—the LFL being 100%. A 5% displayed LFL reading for methane, for example, would be equivalent to 5% multiplied by 4.4%, or approximately 0.22% methane by volume at 20 degrees C. Control of the explosion hazard is usually achieved by sufficient natural or mechanical ventilation, to limit the concentration of flammable gases or vapors to a maximum level of 25% of their *lower explosive or flammable limit*.

### Upper flammability limit

**Upper flammability limit** (UFL): Highest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in the presence of an ignition source (arc, flame, heat). Concentrations higher than UFL or UEL are "too rich" to burn. Operating above the UFL is usually avoided for safety because air leaking in can bring the mixture into combustibility range.

### Influence of temperature, pressure and composition

Flammability limits of mixtures of several combustible gases can be calculated using [Le Chatelier's](/source/Henri_Louis_Le_Chatelier) mixing rule for combustible volume fractions x i {\displaystyle x_{i}} :

- L F L mix = 1 ∑ i x i L F L i {\displaystyle LFL_{\text{mix}}={\frac {1}{\sum _{i}{\frac {x_{i}}{LFL_{i}}}}}}

and similar for UFL.

[Temperature](/source/Temperature), [pressure](/source/Pressure), and the concentration of the oxidizer also influences flammability limits. Higher temperature or pressure, as well as higher concentration of the oxidizer (primarily oxygen in air), results in lower LFL and higher UFL, hence the gas mixture will be easier to explode.

Usually atmospheric air supplies the oxygen for combustion, and limits assume the normal concentration of oxygen in air. Oxygen-enriched atmospheres enhance combustion, lowering the LFL and increasing the UFL, and vice versa; an atmosphere devoid of an oxidizer is neither flammable nor explosive for any fuel concentration (except for gases that can energetically decompose even in the absence of an oxidizer, such as [acetylene](/source/Acetylene)). Significantly increasing the fraction of inert gases in an air mixture, at the expense of oxygen, increases the LFL and decreases the UFL.

## Controlling explosive atmospheres

### Gas and vapor

Controlling gas and vapor concentrations outside the flammable limits is a major consideration in [occupational safety and health](/source/Occupational_safety_and_health). Methods used to control the concentration of a potentially explosive gas or vapor include use of sweep gas, an unreactive gas such as [nitrogen](/source/Nitrogen) or [argon](/source/Argon) to dilute the explosive gas before coming in contact with air. Use of scrubbers or [adsorption](/source/Adsorption) resins to remove explosive gases before release are also common. Gases can also be maintained safely at concentrations above the UEL, although a breach in the storage container can lead to explosive conditions or intense [fires](/source/Fire).

### Dusts

Dusts also have upper and lower explosion limits, though the upper limits are hard to measure and of little practical importance. Lower flammability limits for many organic materials are in the range of 10–50 g/m3, which is much higher than the limits set for health reasons, as is the case for the LEL of many gases and vapours. Dust clouds of this concentration are hard to see through for more than a short distance, and normally only exist inside process equipment.

Flammability limits also depend on the particle size of the dust involved, and are not intrinsic properties of the material. In addition, a concentration above the LEL can be created suddenly from settled dust accumulations, so management by routine monitoring, as is done with gases and vapours, is of no value. The preferred method of managing combustible dust is by preventing accumulations of settled dust through process enclosure, ventilation, and surface cleaning. However, lower flammability limits may be relevant to plant design.

### Volatile liquids

Situations caused by evaporation of flammable liquids into the air-filled void volume of a container may be limited by flexible container volume or by using an immiscible fluid to fill the void volume. [Hydraulic tankers](/source/Hydraulic_tanker) use displacement of water when filling a tank with petroleum.[4]

## Examples

The flammable/explosive limits of some gases and vapors are given below. Concentrations are given in percent by volume of air.

- Class IA liquids with a [flash point](/source/Flash_point) less than 73 °F (23 °C) and [boiling point](/source/Boiling_point) less than 100 °F (38 °C) have a [NFPA 704](/source/NFPA_704) flammability rating of 4

- Class IB liquids with a flash point less than 73 °F (23 °C) and a boiling point equal to or greater than 100 °F (38 °C) and class IC liquids with a flash point equal to or greater than 73 °F (23 °C), but less than 100 °F (38 °C) have a NFPA 704 flammability rating of 3

- Class II liquids with a flash point equal to or greater than 100 °F (38 °C), but less than 140 °F (60 °C) and class IIIA liquids with a flash point equal to or greater than 140 °F (60 °C), but less than 200 °F (93 °C) have a NFPA 704 flammability rating of 2

- Class IIIB liquids with a flash point equal to or greater than 200 °F (93 °C) have a NFPA 704 flammability rating of 1

Substance Flammability limit (%vol.) NFPA class Flash point Minimum ignition energy (mJ) @ proportion in air at which achieved[a][5] Autoignition temperature Lower Upper Acetaldehyde 4.0 57.0 IA −39 °C 0.37 175 °C Acetic acid (glacial) 4 19.9 II 39–43 °C 463 °C Acetic anhydride II 54 °C Acetone 2.6–3 12.8–13 IB −17 °C 1.15 @ 4.5% 465 °C, 485 °C[6] Acetonitrile IB 2 °C 524 °C Acetyl chloride 7.3 19 IB 5 °C 390 °C Acetylene 2.5 100[7] IA Flammable gas 0.017 @ 8.5%; 0.0002 @ 40%, in pure oxygen 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 4.5–5.1[8] 78 IA Flammable gas Benzene 1.2 7.8 IB −11 °C 0.2 @ 4.7% 560 °C 1,3-Butadiene 2.0 12 IA −85 °C 0.13 @ 5.2% Butane, n-butane 1.6 8.4 IA −60 °C 0.25 @ 4.7% 420–500 °C n-Butyl acetate, butyl acetate 1–1.7[6] 8–15 IB 24 °C 370 °C 2-Butanol 1.7 9.8 29 °C 405 °C Isobutanol 1.7 10.9 22–27 °C 415 °C n-Butanol 1.4[6] 11.2 IC 35 °C 340 °C n-Butyl chloride, 1-chlorobutane 1.8 10.1 IB −6 °C 1.24 n-Butyl mercaptan 1.4[9] 10.2 IB 2 °C 225 °C Butyl methyl ketone, 2-hexanone 1[10] 8 IC 25 °C 423 °C Butylene, 1-butylene, 1-butene 1.98[8] 9.65 IA −80 °C Carbon disulfide 1.0 50.0 IB −30 °C 0.009 @ 7.8% 90 °C Carbon monoxide 12[8] 75 IA −191 °C Flammable gas 609 °C Chlorine monoxide IA Flammable gas 1-Chloro-1,1-difluoroethane 6.2 17.9 IA −65 °C Flammable gas Cyanogen 6.0–6.6[11] 32–42.6 IA Flammable gas Cyclobutane 1.8 11.1 IA −63.9 °C[12] 426.7 °C Cyclohexane 1.3 7.8–8 IB −18 – −20 °C[13] 0.22 @ 3.8% 245 °C Cyclohexanol 1 9 IIIA 68 °C 300 °C Cyclohexanone 1–1.1 9–9.4 II 43.9–44 °C 420 °C[14] Cyclopentadiene[15] IB 0 °C 0.67 640 °C Cyclopentane 1.5–2 9.4 IB −37 – −38.9 °C[16][17] 0.54 361 °C Cyclopropane 2.4 10.4 IA −94.4 °C[18] 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[19] 38 °C o-Dichlorobenzene, 1,2-dichlorobenzene 2[20] 9 IIIA 65 °C 648 °C 1,1-Dichloroethane 6 11 IB 14 °C 1,2-Dichloroethane 6 16 IB 13 °C 413 °C 1,1-Dichloroethene 6.5 15.5 IA −10 °C Flammable gas Dichlorofluoromethane 54.7 Non flammable,[21] −36.1 °C[22] 552 °C Dichloromethane, methylene chloride 16 66 Non flammable Dichlorosilane 4–4.7 96 IA −28 °C 0.015 Diesel fuel 0.6 7.5 IIIA >62 °C 210 °C Diethanolamine 2 13 IB 169 °C Diethylamine 1.8 10.1 IB −23 – −26 °C 312 °C Diethyl disulfide 1.2 II 38.9 °C[23] Diethyl ether 1.9–2 36–48 IA −45 °C 0.19 @ 5.1% 160–170 °C Diethyl sulfide IB −10 °C[24] 1,1-Difluoroethane 3.7 18 IA −81.1 °C[25] 1,1-Difluoroethylene 5.5 21.3 −126.1 °C[26] Difluoromethane 14.4[27] Diisobutyl ketone 1 6 49 °C Diisopropyl ether 1 21 IB −28 °C Dimethylamine 2.8 14.4 IA Flammable gas 1,1-Dimethylhydrazine IB Dimethyl sulfide IA −49 °C Dimethyl sulfoxide 2.6–3 42 IIIB 88–95 °C 215 °C 1,4-Dioxane 2 22 IB 12 °C Epichlorohydrin 4 21 31 °C Ethane 3[8] 12–12.4 IA Flammable gas, −135 °C 515 °C Ethanol, ethyl alcohol 3–3.3 19 IB 12.8 °C 365 °C 2-Ethoxyethanol 3 18 43 °C 2-Ethoxyethyl acetate 2 8 56 °C Ethyl acetate 2 12 IA −4 °C 460 °C Ethylamine 3.5 14 IA −17 °C Ethylbenzene 1.0 7.1 15–20 °C Ethylene 2.7 36 IA 0.07 490 °C Ethylene glycol 3 22 111 °C Ethylene oxide 3 100 IA −20 °C Ethyl chloride 3.8[8] 15.4 IA −50 °C Ethyl mercaptan IA Fuel oil No.1 0.7[8] 5 Furan 2 14 IA −36 °C Gasoline (100 octane) 1.4 7.6 IB < −40 °C 246–280 °C Glycerol 3 19 199 °C Heptane, n-heptane 1.05 6.7 −4 °C 0.24 @ 3.4% 204–215 °C Hexane, n-hexane 1.2 7.5 −22 °C 0.24 @ 3.8% 225 °C, 233 °C[6] Hydrogen 4/18.3[28] 75/59 IA Flammable gas 0.016 @ 28%; 0.0012, in pure oxygen 500–571 °C Hydrogen sulfide 4.3 46 IA Flammable gas 0.068 Isobutane 1.8[8] 9.6 IA Flammable gas 462 °C Isobutyl alcohol 2 11 28 °C Isophorone 1 4 84 °C Isopropyl alcohol, isopropanol 2[8] 12 IB 12 °C 398–399 °C; 425 °C[6] Isopropyl chloride IA Kerosene Jet A-1 0.6–0.7 4.9–5 II >38 °C, as jet fuel 210 °C Lithium hydride IA 2-Mercaptoethanol IIIA Methane (natural gas) ISO10156 5.0 14.3 IA Flammable gas 0.21 @ 8.5% 580 °C IEC60079-20-1 4.4 17 Methyl acetate 3 16 −10 °C Methyl alcohol, methanol 6–6.7[8] 36 IB 11 °C 385 °C; 455 °C[6] Methylamine IA 8 °C Methyl chloride 10.7[8] 17.4 IA −46 °C Methyl ether IA −41 °C Methyl ethyl ether IA Methyl ethyl ketone 1.8[8] 10 IB −6 °C 505–515 °C[6] Methyl formate IA Methyl mercaptan 3.9 21.8 IA −53 °C Mineral spirits 0.7[6] 6.5 38–43 °C 258 °C Morpholine 1.8 10.8 IC 31–37.7 °C 310 °C Naphthalene 0.9[8] 5.9 IIIA 79–87 °C 540 °C Neohexane 1.19[8] 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 Octane 1 7 13 °C iso-Octane 0.79 5.94 Pentane 1.5 7.8 IA −40 – −49 °C 0.18 @ 4.4%, as 2-pentane 260 °C n-Pentane 1.4 7.8 IA 0.28 @ 3.3% iso-Pentane 1.32[8] 9.16 IA 420 °C Phosphine IA Propane 2.1 9.5–10.1 IA Flammable gas 0.25 @ 5.2%; 0.0021, in pure oxygen 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[8] 98 IA <21 °C Styrene 1.1 6.1 IB 31–32.2 °C 490 °C Tetrafluoroethylene IA Tetrahydrofuran 2 12 IB −14 °C 321 °C Toluene 1.2–1.27 6.75–7.1 IB 4.4 °C 0.24 @ 4.1% 480 °C; 535 °C[6] Triethylborane −20 °C −20 °C Trimethylamine IA Flammable gas Trinitrobenzene IA Turpentine 0.8[29] IC 35 °C Vegetable oil IIIB 327 °C Vinyl acetate 2.6 13.4 −8 °C Vinyl chloride 3.6 33 Xylenes 0.9–1.0 6.7–7.0 IC 27–32 °C 0.2 m-Xylene 1.1[6] 7 IC 25 °C 525 °C o-Xylene IC 17 °C p-Xylene 1.0 6.0 IC 27.2 °C 530 °C

1. **[^](#cite_ref-5)** Note that for many chemicals it takes the least amount of ignition energy halfway between the LEL and UEL.

## ASTM E681

Image of a flame of R-32 ([Difluoromethane](/source/Difluoromethane)) near its LFL in a 12 L ASTM E-681 apparatus.[27]

In the U.S. the most common method of measuring LFLs and UFLs is [ASTM E681](https://www.astm.org/Standards/E681.htm).[27] This standard test is required for [HAZMAT Class 2 Gases](/source/HAZMAT_Class_2_Gases) and for determining [refrigerant](/source/Refrigerant) flammability classifications. This standard uses visual observations of flame propagation in 5 or 12 L spherical glass vessels to measure the flammability limits. Flammable conditions are defined as those for which a flame propagates outside a 90° cone angle.

## See also

- [Chemistry portal](https://en.wikipedia.org/wiki/Portal:Chemistry)

- [ATEX](/source/ATEX)

- [Flammability](/source/Flammability)

- [Limiting oxygen concentration](/source/Limiting_oxygen_concentration)

- [Minimum ignition energy](/source/Minimum_ignition_energy)

## References

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1. ^ [***a***](#cite_ref-ACC_7-0) [***b***](#cite_ref-ACC_7-1) [***c***](#cite_ref-ACC_7-2) [***d***](#cite_ref-ACC_7-3) [***e***](#cite_ref-ACC_7-4) [***f***](#cite_ref-ACC_7-5) [***g***](#cite_ref-ACC_7-6) [***h***](#cite_ref-ACC_7-7) [***i***](#cite_ref-ACC_7-8) [***j***](#cite_ref-ACC_7-9) [Working with modern hydrocarbon and oxygenated solvents: a guide to flammability](http://www.americanchemistry.com/s_acc/sec_solvents.asp?CID=1488&DID=5735) [Archived](https://web.archive.org/web/20090601224141/http://www.americanchemistry.com/s_acc/sec_solvents.asp?CID=1488&DID=5735) June 1, 2009, at the [Wayback Machine](/source/Wayback_Machine) [American Chemistry Council](/source/American_Chemistry_Council) Solvents Industry Group, pg. 7, January 2008

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1. ^ [***a***](#cite_ref-engineeringtoolbox_9-0) [***b***](#cite_ref-engineeringtoolbox_9-1) [***c***](#cite_ref-engineeringtoolbox_9-2) [***d***](#cite_ref-engineeringtoolbox_9-3) [***e***](#cite_ref-engineeringtoolbox_9-4) [***f***](#cite_ref-engineeringtoolbox_9-5) [***g***](#cite_ref-engineeringtoolbox_9-6) [***h***](#cite_ref-engineeringtoolbox_9-7) [***i***](#cite_ref-engineeringtoolbox_9-8) [***j***](#cite_ref-engineeringtoolbox_9-9) [***k***](#cite_ref-engineeringtoolbox_9-10) [***l***](#cite_ref-engineeringtoolbox_9-11) [***m***](#cite_ref-engineeringtoolbox_9-12) [***n***](#cite_ref-engineeringtoolbox_9-13) [***o***](#cite_ref-engineeringtoolbox_9-14) ["Gases - Explosive and Flammability Concentration Limits"](http://www.engineeringtoolbox.com/explosive-concentration-limits-d_423.html). Retrieved 9 September 2013.

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1. **[^](#cite_ref-11)** ["2-HEXANONE ICSC:0489"](http://www.oit.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc04/icsc0489.htm). *oit.org*. Retrieved 18 March 2018.

1. **[^](#cite_ref-12)** ["IPCS INTOX Site Closed"](http://www.intox.org/databank/documents/chemical/cyanogen/cie430.htm). *www.intox.org*. Retrieved 18 March 2018.

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1. **[^](#cite_ref-14)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 216

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1. **[^](#cite_ref-20)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 244

1. **[^](#cite_ref-21)** Walsh (1989) Chemical Safety Data Sheets, Roy. Soc. Chem., Cambridge.

1. **[^](#cite_ref-22)** ["Encyclopedia.airliquide.com"](https://web.archive.org/web/20200526073305/https://encyclopedia.airliquide.com/sds/en/042_AL_EN.pdf) (PDF). Archived from [the original](http://encyclopedia.airliquide.com/sds/en/042_AL_EN.pdf) (PDF) on 26 May 2020. Retrieved 25 June 2023.

1. **[^](#cite_ref-23)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 266

1. **[^](#cite_ref-24)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 281

1. **[^](#cite_ref-25)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 286

1. **[^](#cite_ref-26)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 296

1. **[^](#cite_ref-27)** Yaws, Carl L.; Braker, William; *Matheson Gas Data Book* Published by McGraw-Hill Professional, 2001 pg. 301

1. ^ [***a***](#cite_ref-:0_28-0) [***b***](#cite_ref-:0_28-1) [***c***](#cite_ref-:0_28-2) Kim, Dennis K.; Klieger, Alexandra E.; Lomax, Peter Q.; Mccoy, Conor G.; Reymann, Jonathan Y.; Sunderland, Peter B. (14 September 2018). ["An improved test method for refrigerant flammability limits in a 12 L vessel"](https://doi.org/10.1080/23744731.2018.1434381). *Science and Technology for the Built Environment*. **24** (8): 861–866. [Bibcode](/source/Bibcode_(identifier)):[2018STBE...24..861K](https://ui.adsabs.harvard.edu/abs/2018STBE...24..861K). [doi](/source/Doi_(identifier)):[10.1080/23744731.2018.1434381](https://doi.org/10.1080%2F23744731.2018.1434381). [ISSN](/source/ISSN_(identifier)) [2374-4731](https://search.worldcat.org/issn/2374-4731). [S2CID](/source/S2CID_(identifier)) [139489210](https://api.semanticscholar.org/CorpusID:139489210).

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1. **[^](#cite_ref-30)** ["Combustibles"](https://web.archive.org/web/20160303191927/http://www.afcintl.com/pdf/combustibles.pdf) (PDF). *afcintl.com*. Archived from [the original](http://www.afcintl.com/pdf/combustibles.pdf) (PDF) on 3 March 2016. Retrieved 18 March 2018.

## Further reading

- David R. Lide, Editor-in-Chief; *CRC Handbook of Chemistry and Physics, 72nd edition*; CRC Press; [Boca Raton](/source/Boca_Raton%2C_Florida), Florida; 1991; [ISBN](/source/ISBN_(identifier)) [0-8493-0565-9](https://en.wikipedia.org/wiki/Special:BookSources/0-8493-0565-9)

v t e Fire protection Fundamental concepts Backdraft Boiling liquid expanding vapor explosion (BLEVE) Boilover Combustibility and flammability Conflagration Dangerous goods (HAZMAT) Deflagration Detonation Dust explosion Enthalpy of vaporization Explosive Fire classification Fire control Fire loading Fire point Fire triangle Flammability diagram Flammability limit Flammable liquid Flashover Flash point Friction loss Gas leak Heat transfer Jet fire K-factor (fire protection) Pool fire Pyrolysis Spontaneous combustion Structure fire Thermal radiation Water pressure Technology Active fire protection Automatic fire suppression Condensed aerosol fire suppression Detonation flame arrester External water spray system Fire bucket Fire prevention Fire protection Fire retardant Fire-retardant fabric Fire retardant gel Fire-safe polymers Fire safety Fire sprinkler system Fire suppression system Firefighting foam Flame arrester Flame retardant Flashback arrestor Fusible link Gaseous fire suppression Hypoxic air technology for fire prevention Inerting system Intumescent Passive fire protection Personal protective equipment (PPE) Relief valve Spark arrestor Tank blanketing Vehicle fire suppression system Building design Annulus (firestop) Area of refuge Booster pump Compartmentation Crash bar Electromagnetic door holder Electromagnetic lock Emergency exit Emergency light Exit sign Fire curtain Fire cut Fire damper Fire door Fire escape Fire extinguisher Fire hose Fire hydrant Fire pump Fire sprinkler Firestop Firestop pillow Firewall (construction) Grease duct Heat and smoke vent Packing (firestopping) Penetrant (mechanical, electrical, or structural) Penetration (firestop) Pressurisation ductwork Safety glass Smoke control Smoke damper Smoke exhaust ductwork Smokeproof enclosure Standpipe (firefighting) Fire alarm systems Aspirating smoke detector Carbon monoxide detector Circuit integrity Explosive gas leak detector Fire alarm call box Fire alarm control panel Fire alarm notification appliance Fire drill Flame detector Heat detector Manual fire alarm activation Smoke detector Professions, trades, and services Duct cleaning Fire insurance Fire protection engineering Fireproofing Fire-resistance rating Fire Safety Evaluation System (FSES) Fire test Kitchen exhaust cleaning Listing and approval use and compliance Sprinkler fitting Industry organizations Institution of Fire Engineers (IFE) National Council of Examiners for Engineering and Surveying (NCEES) National Fire Protection Association (NFPA) Society of Fire Protection Engineers (SFPE) Underwriters Laboratories (UL) Standards CE marking EN 3 EN 54 EN 16034 Flame spread GHS hazard statements GHS precautionary statements Life Safety Code (NFPA 101) List of R-phrases List of S-phrases Safety data sheet UL 94 Awards Arthur B. Guise Medal Harry C. Bigglestone Award See also Template:Fire Template:Firefighting Template:HVAC Category Commons

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Adapted from the Wikipedia article [Flammability limit](https://en.wikipedia.org/wiki/Flammability_limit) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Flammability_limit?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.