A flammable hazard sign in Arabic

A flammable liquid is any liquid with a flash point at or below a certain threshold, as defined by some governing body.


The Occupational Safety and Health Administration (OSHA) of the United States Department of Labor defines a liquid as flammable if it has a flash point at or below 199.4° F (93° C).[1] Prior to bringing regulations in line with the United Nations Globally Harmonized System of Classification and Labeling of Chemicals (GHS) in 2012, OSHA considered flammable liquids to be those with a flash point below 100° F (37.8° C). Those with flash points above 100° F and below 200° F (93.3° C) were classified as combustible liquids.[2][3] Studies show that the actual measure of a liquids flammability, its flash point, is dependent on altitude.[4]

Categorization

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Both OSHA and GHS further divide flammable liquids into 4 categories:

  • Category I flammable liquids are those with boiling points ≤ 95° F (35° C) and flash points < 73° F (23° C)[1][5]
  • Category II flammable liquids are those with boiling points > 95° F and flash points < 73° F[1][5]
  • Category III flammable liquids are those with flash points > 73° F and ≤ 140° F (60° C)[1][5]
  • Category IV flammable liquids are those with flash points > 140° F and ≤ 199.4°F[1][5]

These categorizations are dependent upon a set altitude and atmospheric pressure, as both boiling point and flash point change with changes in pressure.[4][6]


Labeling

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Both GHS and OSHA require the labeling of flammable liquids, on containers and safety data sheets, as follows:[3][5]

Category I Category II Category III Category IV
Symbol Flame Flame Flame none
Signal Word Danger Danger Warning Warning
Hazard Statement Extremely flammable liquid and vapour Highly flammable liquid and vapor Flammable liquid and vapour Combustible liquid
 
Flammable liquid labels on fuel tanks


References

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  1. ^ a b c d e "1910.106 - Flammable liquids. | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2019-03-06.
  2. ^ "But It Wasn't Flammable Before! GHS Changed the Meaning of 'Flammable Liquids'". EHS Daily Advisor. 2015-09-23. Retrieved 2019-03-08.
  3. ^ a b "HCS/HazCom 2012 Final Rule & Appendices | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2019-03-08.
  4. ^ a b Ding, Chao, et al. “Experimental Study of the Flash Point of Flammable Liquids under Different Altitudes in Tibet Plateau.” Fire & Materials, vol. 38, no. 2, Mar. 2014, pp. 241–246. EBSCOhost, doi:10.1002/fam.2177.
  5. ^ a b c d e Globally harmonized system of classification and labelling of chemicals (GHS). United Nations. Economic Commission for Europe. Secretariat. (Seventh revised edition ed.). New York. ISBN 9789211171310. OCLC 994197992. {{cite book}}: |edition= has extra text (help)CS1 maint: others (link)
  6. ^ "Standard Temperature and Pressure". www.kentchemistry.com. Retrieved 2019-03-11.