Class B fire

In fire classes, a Class B fire is a fire in flammable liquids or flammable gases, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, or alcohols.[1] For example, propane, natural gas, gasoline and kerosene fires are types of Class B fires.[2][3] The use of lighter fluid on a charcoal grill, for example, creates a Class B fire.[4] Some plastics are also Class B fire materials.[3]

Attempts to extinguish a grease fire during a demonstration

Class B fires are distinguished from the other fire classes: Class A fires ("ordinary combustibles" such as wood, paper, or rubber); Class C fires (in which the burning material is energized electrical equipment) and Class D fires (in which the burning material is combustible metals).[3] The less-commonly-used Class K (known outside the United States as Class F) refers to fires involving cooking oil or fat; these materials are technically part of Class B.[5]

Fires are classified by the proper extinguishing agent. While water is used on Class A fires, using water on a Class B fire (such as a grease fire) is extremely dangerous.[3][5] This is because burning grease is hotter than the boiling point of water (212 degrees Fahrenheit or 100 degrees Celsius); when water is placed on grease, it creates steam which expands rapidly and splatters, causing burns and spreading the fire).[3] Because of this, Class A fire extinguishers use water, while Class B fire extinguishers use dry chemicals (foam or powder),[5] such as aqueous film-forming foam, multi-purpose dry chemicals such as ammonium phosphate, and halogenated agents (such as Halon 1301 and Halon 1211)[6] or highly pressurized carbon dioxide.[5] Some fire extinguishers contain chemicals designed to fight both Class A and Class B fires.[6]

Grease and cooking oil fires pose a safety risk. One ten-year study, examining the years 1976 to 1985, found that 4.7% of hospitalized burn patients suffered burns from hot grease or oil, with 78% of such injuries occurring in the home.[7] According to the National Fire Protection Association, between 2010 and 2014, nearly half (46%) of home structure fires reported to fire departments in the United States involved cooking; over the same time period, cooking equipment was implicated in 19% of home fire deaths, 44% of home fire injuries, and 17% of total direct property damage.[8] Grease fires are an object of study in food science.[9]

See alsoEdit

  • Grease duct – a duct designed to vent grease-laden flammable vapors to prevent them from building up near the flame of cooking apparatuses
  • Exhaust hood – a device containing a mechanical fan that for use above the stove or cooktop in the kitchen to remove airborne elements produced by cooking


  1. ^ NFPA's Illustrated Dictionary of Fire Service Terms, p. 23 (National Fire Protection Association/Jones and Bartlett Publishers: 2006).
  2. ^ James R. Gillespie & Frank Flanders, Modern Livestock & Poultry Production, 8th ed. (Centgage Learning: 2009), p. 76.
  3. ^ a b c d e International Association of Fire Chiefs/National Fire Protection Association, Fire Inspector: Principles and Practice (Jones and Bartlett Publishers, 2012), pp. 204-06.
  4. ^ Robert H. Hill, Jr. & David C. Finster, Laboratory Safety for Chemistry Students (2d ed.: John Wiley & Sons, 2016).
  5. ^ a b c d JB Crippin, "Types of Fires" in Forensic Chemistry (ed. Max M. Houck: Academic Press, 2015), p. 219.
  6. ^ a b Lon H. Ferguson & Christopher A. Janicak, Fundamentals of Fire Protection for the Safety Professional (2d ed. 2015), pp. 203-04.
  7. ^ Schubert, Warren; Ahrenholz, David H.; Solem, Lynn D. (1990). "Burns from Hot Oil and Grease: A Public Health Hazard". Journal of Burn Care & Rehabilitation. 11 (6): 558–62. doi:10.1097/00004630-199011000-00014. PMID 2286612.
  8. ^ Marty Ahrens, Home Fires Involving Cooking Equipment, National Fire Protection Association (November 2016).
  9. ^ Ingolf Gruen, Out of the Frying Pan and into the Grease Fire: A Case Study in Food Science, National Center for Case Study Teaching in Science, University at Buffalo (May 31, 2003).