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Creating cotton that is fireproof and comfortable

State-of-the-art flame retardant cotton textiles suffer from release of formaldehyde and are uncomfortable to wear. Empa scientists managed to circumvent this problem by creating a physically and chemically independent network ...

'Cool flames' ignited in space

A discovery has been made in Earth's orbit—steady spherical cool diffusion flames. Measurements in these flames could help improve the engines of the future.

The amazing world of flame balls, doughnuts and horseshoes

Flame balls are gentle and fragile spherical flames that up till recently could only exist in conditions of near-zero gravity. Researchers at TU/e have managed to observe flameballs at normal earth-bound conditions, and thus, ...

Study reveals high levels of contaminants in killer whales

Little is known concerning environmental contaminants in predators at the top of a food chain. A study published in Environmental Toxicology and Chemistry has demonstrated that new types of brominated flame retardants accumulate ...

Want a healthier home? Start with your couch

A new study shows that when people replace their old couch with a new one that has no added flame retardants, levels of the harmful chemicals in household dust drop significantly. Replacing the foam inside the couch cushions ...

Blue whirl flame structure revealed with supercomputers

Lightning struck a bourbon warehouse, setting fire to a cache of 800,000 gallons of liquor in the Bardstown countryside of Kentucky in 2003. Some of it spilled into a nearby creek, spawning a massive fire tornado, or 'bourbonado,' ...

Scientists find harmful chemicals in household dust

Since the 1970s, chemicals called brominated flame retardants (BFRs) have been added to a host of consumer and household products, ranging from electronics and mattresses to upholstery and carpets. While they were intended ...

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Flame

A flame (from Latin flamma) is the visible (light-emitting), gaseous part of a fire. It is caused by a highly exothermic reaction (for example, combustion, a self-sustaining oxidation reaction) taking place in a thin zone. If a fire is hot enough to ionize the gaseous components, it can become a plasma.

Color and temperature of a flame are dependent on the type of fuel involved in the combustion, as, for example, when a lighter is held to a candle. The applied heat causes the fuel molecules in the candle wax to vaporize. In this state they can then readily react with oxygen in the air, which gives off enough heat in the subsequent exothermic reaction to vaporize yet more fuel, thus sustaining a consistent flame. The high temperature of the flame causes the vaporized fuel molecules to decompose, forming various incomplete combustion products and free radicals, and these products then react with each other and with the oxidizer involved in the reaction. Sufficient energy in the flame will excite the electrons in some of the transient reaction intermediates such as CH and C2, which results in the emission of visible light as these substances release their excess energy (see spectrum below for an explanation of which specific radical species produce which specific colors). As the combustion temperature of a flame increases (if the flame contains small particles of unburnt carbon or other material), so does the average energy of the electromagnetic radiation given off by the flame (see blackbody).

Other oxidizers besides oxygen can be used to produce a flame. Hydrogen burning in chlorine produces a flame and in the process emits gaseous hydrogen chloride (HCl) as the combustion product. Another of many possible chemical combinations is hydrazine and nitrogen tetroxide which is hypergolic and commonly used in rocket engines. Fluoropolymers can be used to supply fluorine as an oxidizer of metallic fuels, e.g. in the magnesium/teflon/viton composition.

The chemical kinetics occurring in the flame are very complex and involves typically a large number of chemical reactions and intermediate species, most of them radicals. For instance, a well-known chemical kinetics scheme, GRI-Mech, uses 53 species and 325 elementary reactions to describe combustion of biogas.

There are different methods of distributing the required components of combustion to a flame. In a diffusion flame, oxygen and fuel diffuse into each other; where they meet the flame occurs. In a premixed flame, the oxygen and fuel are premixed beforehand, which results in a different type of flame. Candle flames (a diffusion flame) operate through evaporation of the fuel which rises in a laminar flow of hot gas which then mixes with surrounding oxygen and combusts.

This text uses material from Wikipedia, licensed under CC BY-SA