Fire triangle - wikipedia Fire triangle This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( November 2016 ) The Fire Triangle. The Fire Triangle or Combustion Triangle or '' Fire Diamond '' are simple models for understanding the necessary ingredients for most fires. The triangle illustrates the three elements a fire needs to ignite : heat, fuel, and an oxidizing agent ( usually oxygen ). A fire naturally occurs when the elements are present and combined in the right mixture, meaning that fire is actually an event rather than a thing. A fire can be prevented or extinguished by removing any one of the elements in the fire triangle. For example, covering a fire with a fire blanket removes the oxygen part of the triangle and can extinguish a fire. In large fires where firefighters are called in, decreasing the amount of oxygen is not usually an option because there is no effective way to make that happen in an extended area. Contents 1 Fire Tetrahedron 2 Oxidizer 3 Extinction of the fire 4 Role of water in fire - fighting 5 Multi-scale fire triangles for wildland fires 6 See also 7 Notes 8 References Fire tetrahedron Not to be confused with NFPA 704, also called the fire diamond. The fire tetrahedron The fire tetrahedron represents the addition of a component in the chemical chain reaction, to the three already present in the fire triangle. Once a fire has started, the resulting exothermic chain reaction sustains the fire and allows it to continue until or unless at least one of the elements of the fire is blocked. Foam can be used to deny the fire the oxygen it needs. Water can be used to lower the temperature of the fuel below the ignition point or to remove or disperse the fuel. Halon can be used to remove free radicals and create a barrier of inert gas in a direct attack on the chemical reaction responsible for the fire. Combustion is the chemical reaction that feeds a fire more heat and allows it to continue. When the fire involves burning metals like lithium, magnesium, titanium, etc. ( known as a class - D fire ), it becomes even more important to consider the energy release. The metals react faster with water than with oxygen and thereby more energy is released. Putting water on such a fire results in the fire getting hotter or even exploding. Carbon dioxide extinguishers are ineffective against certain metals such as titanium. Therefore, inert agents ( e.g. dry sand ) must be used to break the chain reaction of metallic combustion. In the same way, as soon as one of the four elements of the tetrahedron is removed, combustion stops. Oxidizer The oxidizer is the other reactant of the chemical reaction. In most cases, it is the ambient air, and in particular one of its components, oxygen ( O ). By depriving a fire of air, it can be extinguished ; for example, when covering the flame of a small candle with an empty glass, fire stops ; to the contrary, if air is blown over a wood fire with bellows, the fire is activated by the introduction of more air. In certain torches, gaseous oxygen is introduced to improve combustion. Some chemicals, such as fluorine gas, perchlorate salts such as ammonium perchlorate, or chlorine trifluoride, act as oxidisers, sometimes more powerful ones than oxygen itself. A fire based on a reaction with these oxidisers can be very difficult to put out until the oxidiser is exhausted ; that leg of the fire triangle can not be broken by normal means ( i.e., depriving it of air will not smother it ). In certain cases such as some explosives, the oxidizer and combustible are the same ( e.g., nitroglycerin, an unstable molecule that has oxidizing parts in the same molecule as the oxidizeable parts ). Reaction is initiated by an activating energy, in most cases, it is heat. Several examples include friction, as in case of matches, heating an electrical wire, a flame ( propagation of fire ), or a spark ( from a lighter or from any starting electrical device ). There are also many other ways to bring sufficient activation energy including electricity, radiation, and pressure, all of which will lead to a temperature rise. In most cases, heat production enables self - sustainability of the reaction, and enables a chain reaction to grow. The temperature at which a liquid produces sufficient vapor to get a flammable mix with self - sustainable combustion is called its flash - point. Extinction of the fire To stop a combustion reaction, one of the three elements of the fire - triangle has to be removed. Without sufficient heat, a fire can not begin, and it can not continue. Heat can be removed by the application of a substance which reduces the amount of heat available to the fire reaction. This is often water, which absorbs heat for phase change from water to steam. Introducing sufficient quantities and types of powder or gas in the flame reduces the amount of heat available for the fire reaction in the same manner. Scraping embers from a burning structure also removes the heat source. Turning off the electricity in an electrical fire removes the ignition source. Without fuel, a fire will stop. Fuel can be removed naturally, as where the fire has consumed all the burnable fuel, or manually, by mechanically or chemically removing the fuel from the fire. Fuel separation is an important factor in wildland fire suppression, and is the basis for most major tactics, such as controlled burns. The fire stops because a lower concentration of fuel vapor in the flame leads to a decrease in energy release and a lower temperature. Removing the fuel thereby decreases the heat. Without sufficient oxygen, a fire can not begin, and it can not continue. With a decreased oxygen concentration, the combustion process slows. Oxygen can be denied to a fire using a carbon dioxide fire extinguisher, a fire blanket or water. Role of water in fire - fighting Water can have two different roles. In the case of a solid combustible, the solid fuel produce pyrolyzing products under the influence of heat, commonly radiation. This process is halted by the application of water, since water is more easily evaporated than the fuel is pyrolyzed. Thereby energy is removed from the fuel surface and it is cooled and the pyrolysis is stopped, removing the fuel supply to the flames. In fire fighting, this is referred to as surface cooling. In the gas phase, i.e. in the flames or in the smoke, the combustible can not be separated from the oxidizer, and the only possible action consists of cooling down. In this case, water droplets are evaporated in the gas phase, thereby lowering the temperature and adding water vapour making the gas mixture non combustible. This requires droplets of a size less than about 0.2 mm. In fire fighting, this is referred to as gas cooling or smoke cooling. Cases also exist where the ignition factor is not the activation energy. For example, a smoke explosion is a very violent combustion of unburned gases contained in the smoke created by a sudden fresh air input ( oxidizer input ). The interval in which an air / gas mix can burn is limited by the explosive limits of the air. This interval can be very small ( kerosene ) or large ( acetylene ). Water can not be used on certain type of fires : Fires where live electricity is present -- as water conducts electricity it presents an electrocution hazard. Hydrocarbon fires -- as it will only spread the fire because of the difference in density / hydrophobicity. For example, adding water to a fire with an oil source will cause the oil to spread, since oil and water do not mix. Metal fires -- as these fires produce huge amounts of energy ( up to 7.550 calories / kg for aluminium ) and water can also create violent chemical reactions with burning metal ( possibly even serving as an additional oxidizing agent ). Since these reactions are well understood, it has been possible to create specific water - additives which will allow : A better heat absorption with a higher density than water. Carrying free radical catchers on the fire. Carrying foaming agents to enable water to stay on the surface of a liquid fire and prevent gas release. Carrying specific reactives which will react and change the nature of the burning material. Water - additives are generally designed to be effective on several categories of fires ( class A + class B or even class A + class B + class F ), meaning a better global performance and usability of a single extinguisher on many different types of fires ( or fires that involve several different classes of materials ). Multi-scale fire triangles for wildland fires Multi-scale fire triangles describing the elements of wildland fire at the scale of the flame, a wildfire, and a fire regime. Adapted from Moritz et al. ( 2005 ) Wildfire, complexity, and highly optimized tolerance. Proceedings of the National Academy of Science 102, 17912 - 17917. In the context of wildland fire, the fire triangle can be scaled up to apply to understand fire spread over landscapes ( scales of days and several km ) and recurrence of fire over time ( scales of decades and hundreds of km ). Thus, while heat is important to ignite a flame, topography is important for aiding fire spread especially by preheating upslope fuels, and ignitions sources are important to help explain recurrence on longer time scales. Similarly, while oxygen is relevant to sustain a flame, weather and associated winds feed oxygen into a spreading fire, and the longer - term pattern of weather is summarized as climate. Lastly, fuels is the term to describe what burns in a single flame to the range of materials burnt in a spreading wildfire, but fuels vary over larger space and time scales in what is called vegetation. At the smallest scale, the combustion fire triangle, individual fuel particles are ignited once at a critical temperature, and fire transfers energy to the nearest surroundings. Combustion events range on the scale of several seconds to a couple of days and their effects are monitored at the quadrant scale. The largest scale, in contrast, describes the fire regime concept. Global climate change drives drives many of the factors involved in the ' wildfire ' and the ' fire regime ' triangles. For example, with respect to the fire regime, a particular vegetation type will support a characteristic fire in terms of recurrence, intensity, seasonality and biological effects ; a change in vegetation type will have implications for a changing fire regime. See also Wikimedia Commons has media related to Fire triangle. Look up fire triangle in Wiktionary, the free dictionary. Glossary of firefighting terms Fire classes Notes Jump up ^ The Fire Triangle Archived 2012 - 04 - 06 at the Wayback Machine., Hants Fire brigade, accessed June 2009 Jump up ^ IFSTA, 2008 p. 88. Jump up ^ `` What is a fire illuminate shape ? triangle ''. FireRescue1. Retrieved 2017 - 02 - 14. Jump up ^ `` The Fire Tetrahedron ( A pyramid ) ''. Information about the Fire Triangle / Tetrahedron and Combustion. Safelincs Ltd. Retrieved 30 August 2012. ^ Jump up to : ( 1 ) Titanium MSDS Jump up ^ Moritz, Max A. ; Morais, Marco E. ; Summerell, Lora A. ; Carlson, J.M. ; Doyle, John ( 2005 - 12 - 13 ). `` Wildfires, complexity, and highly optimized tolerance ''. Proceedings of the National Academy of Sciences of the United States of America. 102 ( 50 ) : 17912 -- 17917. doi : 10.1073 / pnas. 0508985102. ISSN 0027 - 8424. PMC 1312407. PMID 16332964. References IFSTA ( 2008 ). `` Essentials of Fire Fighting and Fire Department Operations 5th Edition '' hide Firefighting Personnel Fire captain Fire chief Fire marshal Fire police Handcrew Station officer Volunteer fire department Women in firefighting Facilities Fire department List of fire departments Fire lookout tower Fire station Apparatus Airport crash tender Fire bike Fire chief 's vehicle Fire engine Firefighting apparatus HazMat Heavy rescue Light and air Quint Tender Wildland tender Wildland engine Equipment Bunker gear Escape chair Fire extinguisher Fire hose Fire hydrant Fire retardant Fire shelter Fireman 's pole Fireman 's switch Flame retardant Fog nozzle Halligan bar Hard suction hose Hazmat suit Heat detector Hose bridge Hydraulic rescue tools ( `` Jaws of life '' ) Nomex PASS Proximity suit SCBA Siren Smoke detector Thermal imaging camera Terminology Backdraft Dead man zone Deluge gun Draft Fire classes Fire control Fire safety Fire triangle Fireman 's carry Firewall Flash fire Forcible entry Gaseous fire suppression Stop, drop and roll Structure fire Two - in, two - out Ventilation Miscellaneous Fire camp Fire engine red Fire photography Fire protection engineering Foam Geography of firefighting History of firefighting International Association of Fire Fighters International Firefighters ' Day List of firefighting films Muster Saint Florian World Firefighters Games World Police and Fire Games Wildland firefighting Equipment and tactics Aerial firefighting Controlled burn Driptorch Fire hose Fire lookout tower Fire retardant Fire retardant gel Fire trail Firebreak Firefighting apparatus Firefighting foam Helicopter bucket Hose pack MAFFS Pulaski Wildland fire engine Wildland water tender Wildfire suppression equipment and personnel Personnel Engine crew Handcrew Helitack Hotshots Lookout Smokejumper By location Australia United States ( California, Washington ) Lists Glossary of wildfire terms List of wildfires Commons Retrieved from `` https://en.wikipedia.org/w/index.php?title=Fire_triangle&oldid=843757803 '' Categories : Firefighting Fire Hidden categories : Webarchive template wayback links Articles needing additional references from November 2016 All articles needing additional references All accuracy disputes Articles with disputed statements from April 2017 Talk Contents About Wikipedia Català Dansk Deutsch Ελληνικά Español Euskara فارسی Français Italiano Nederlands Português Română Simple English Svenska தமிழ் West - Vlams 粵語 中文 10 more Edit links This page was last edited on 31 May 2018, at 07 : 56. 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Question: what are the three components of the fire triangle
Answer: heat