Flame extinguishment

If any one of the principle elements of the combustion process cam be removed from a fire, it will be extinguished. The principle methods of extinguishment are discussed below. 

Cooling (water spray, water injection, water flooding, etc.) 

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Figure 4 illustrates the trend in adiabatic flame temperatures with heat of combustion as described. Also indicated is the consequence of another statistical result, ie, flames extinguish at a roughly common low limit (1200°C). This corresponds to heat-release density of ca 1.9 MJ/m (50 Btu/ft ) of fuel—air mixtures, or half that for the stoichiometric ratio. It also corresponds to flame temperature, as indicated, of ca 1220°C. Because these are statistical quantities, the same numerical values of flame temperature, low limit excess air, and so forth, can be expected to apply to coal—air mixtures and to fuels derived from coal (see Fuels, synthetic). 

Third, since the pulsating instability observed for the planar unstretched flame was expected to be promoted by positive stretch, pulsation may develop beyond a critical stretch rate smaller than the static extinction limit. As pulsating extinction occurred at a smaller stretch rate than the steady extinction limit, the flame extinguished in the pulsating, instead of the steadily propagating mode, and the flammable range was accordingly narrowed. 

Takahashi, F., Linteris, G., and Katta, V.R., Further studies of cup-bumer flame extinguishment, 16th Annual Halon Options Technical Working Conference (HOTWC), Albuquerque, NM, May 2006. 

The active chain carriers are replaced with the much less active halogen radical slowing the rate of energy production and helping flame extinguishment. 

The data reported in Table VI for Halon 1301 concentration required for flame extinguishment vary in the range of 3 to %, which is comparable to the range found for ordinary combustibles. Thus maintenance of Halon 1301 concentrations in excess of is expected to extinguish fires in the ignition zone for the FRC materials this concentration limit satisfies the current Halon 1301 requirements for fire suppression systems for tracked vehicles. 

The flame extinguishment data for Halon 1301 measured in this study suggest that for extended ignition zone covering large surface areas, maintenance of a concentration in excess of A by volume would be sufficient for the control of fire growth and extinguishment for the MTL samples. 

In household heating systems running on gas or oil the presence of the flame has to be surveyed. If the flame extinguishes, a burner control system has to reignite the flame or the fuel supply has to be stopped. Several flame-sensing mechanisms are used in the control systems. 

Bromine is thought to be essential for plants and animals, although no known biological role has been established. It has flame-extinguishing characteristics and is used in fireproofing agents and to make flame-resistant plastics. 

Flammenausloschenzusatz. Ger for "Flame Extinguishing Addition , described here under... 

Soldaini and Bert e s method. 20 c.c. of the oil and a few scraps of pumice are placed in a three-bulbed distillation flask (see p. 278) holding about 70-75 c.c., the flask being connected with a small condenser and closed with a cork traversed by a thermometer. Around the flask—which should rest on an asbestos-gauze—is placed an asbestos card sleeve, which surrounds it at a distance of about 1 cm. and reaches almost to the lowest bulb of the neck. To the free end of the condenser is fitted a graduated cylinder. The oil is then boiled at the ordinary pressure so that one drop falls into the cylinder about every two seconds. When the distillate in the cylinder amounts to one-half the amount of oil taken, i.e. 10 c.c., the cylinder is replaced by an ordinary test-tube and the flame extinguished. The few drops of subsequent distillate are returned to the residue in the distillation flask. 

Plamyagacrtel (Flame Extinguisher). The Russians used essentially the same materials described in Vol 6 of the Encycl under Flash-Reducing (or Antiflash) Agents (pp F96-L to F98-R), and Flash Reduction in German Projectiles and Propellants (pp F99-L to F100-L)... 

Typically, a phosphorus-based FR is designed to develop its activity just before the start of the decomposition of the specific polymer for which it is used. They offer a partial gas-phase contribution to the flame extinguishing effect, which is comparable to bromine- or chlorine-containing FRs. 

Critical flux is defined as the radiant flux at which the flame extinguishes or the radiant flux after a test period of 30 min, whichever is the lower (i.e., the flux corresponding with the furthest extent of spread of flame). 

Thus, a flame-extinguishing smoke of very fine salt particles is produced by the decomposition reaction itself. Combinations of salt-pair reactions and classic detonation reactions quenched by adding salt are possible. 

Figure 29.2 Various stages of the UL 94 vertical burning test (a) application of flame (b) observation of burning time (c) flame extinguishes...

Ammonium nitrate Dinitrn-benzol Trench s flame-extinguishing compound 85 per cent, to 5... 

NO flow of feedwater. NO level in drum. NO fuel flow. LICV closed. Loss of feedwater pressure. Massive leak. Fuel line closed. Loss of level in drum and explosion of drum by flame impingement on dry shell if flame continues. Same as above. Flame extinguished. No steam generation. 

Increased Flame Stability. Oxygen-enhanced flames have higher flame speeds than air/fuel flames. This means that in order to prevent either flashback or flame extinguishment the minimum gas exit velocities for an OEC flame must be higher than those for an air/fuel flame. The potential for flashback is discussed further in Section 1.3.4.5. Harris et al.30 have defined the critical boundary velocity gradient for a cylindrical tube as follows ... 

Many theories attempt to explain the mechanism of flame retardancy. The flame retarding action is thought to take place in the vapor phase above the burning surface. For antimony oxide to work, the halogen and antimony oxide must be found in a vapor phase which will occur at temperatures above 315°C. At these temperatures, antimony halides and oxyhalides are formed and act as flame extinguishing moieties by quenching radicals as they form. 

In turn, hold the soaked end of each of the splints in the flame for a short time. Observe and record the color of the flames. Extinguish the splint as soon as the flame is no longer colored. 

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