Burn time

A third type of commercial matches popular in South America is the wax vestas with a center of cotton threads or of a roUed and compressed thin and tough paper surrounded by and impregnated with wax each match is a miniature candle of long (ca 1 min) burning time. 

Burning times for coal particles are obtained from integrated reaction rates. For larger particles (>100 fim) and at practical combustion temperatures, there is a good correlation between theory and experiment for char burnout. Experimental data are found to obey the Nusselt "square law" which states that the burning time varies with the square of the initial particle diameter (t ). However, for particle sizes smaller than 100 p.m, the Nusselt... 

Theoretical modeling of single-droplet combustion has provided expressions for evaporation and burning times of the droplets and the subsequent coke particles. A more thorough treatment of this topic is available (88,91—93,98). 

Endurance Burn Under certain cou(itious, a successfully arrested flame may stabilize on the unprotected side of an arrester element. Should this condition not be corrected, the flame will eventually penetrate the arrester as the channels become hot. An endurance burn time can be determined by testing, which specifies that the arrester has withstood a stabilized flame without penetration for a given period. The test should address either the actual or worst-case geometry, since heat transfer to the element will depend on whether the flame stabilizes on the top, bottom, or horizontal face. In general, the endurance burn time identified by test should not be regarded as an accurate measure of the time available to take remedial action, since test conditions will not necessarily approximate the worst possible practical case. Temperature sensors may be incorporated at the arrester to indicate a stabilized flame condition and either alarm or initiate appropriate action, such as valve closure. 

Safe Burning Time The period of stabilized burning on a flame arrester without flame being transmitted through the arrester. 

Fay and Lewis (1977) used spherical gas samples inside soap bubbles whose volumes ranged from 20 to 190 cm. Typically, a sphere was ignited with resistance wire, and the combustion process was then filmed with a high-speed camera. The fireball s maximum height and diameter, as well as the time needed to complete combustion, were evaluated. The fireball s thermal radiation was sensed by a radiation detector. Figure 6.3 relates fireball burning time and size to initial propane... 

Figure 6.3. Burning time (tp) and maximum fireball diameter (O) as function of initial fuel volume (Wy) of propane (Fay and Lewis 1977).

Pool burning time is defined as tlie time for tlie pool fire to bum itself out. It is ealeulated by... 

Applying Equation (7.2.10) tlie pool burning time is calculated as follow ... 

Calculate the total burning time of tlie octane pool in Illustrative Exatiiple 3. Calculate tlie peak overpressure of a 50-pound TNT explosion at a distance 200 feet from the ignition point, if tlie peak oi erpressure at 1000 feel is 0.10 psi when 150 pounds of TNT is detonated. 

Brenn-barkeit, /. combustibility, -blase, /, alembic, still, -cylinder, m. (Pharm.) moxa. -dauer, /. burning time or period (of lamps, etc.) life. 

Illumination. The emission of any lamp tends to decrease with age and must be replaced when the time of maximum usage is reached a log should be kept of the burning time of each lamp. 

Demand for a delay powd capable of withstanding the effects of repeated impacts on a hard surface, typical of skip bombing, lead to the development of Ba chromate—Mn—S compositions. They proved satisfactory in the M16-A1 delay element, with burning times of 8—J1 secs obtained with compns contg Ba chromate 70-74, Mn 20—22 and S 3-4%. Storage at 65° resulted in increased burning time,... 

Some nitriles are expl, especially if they contain several —CN groups or a combination of —CN and —N02 groups. Other nitriles have been considered for use in double-base propints as they cool the flame and provide longer burning times a variety of alkyl nitriles have been investigated as plasticizers (Ref 7)... 

Nitroindene Polymer (N.I.P.). Evaluated at PicArsn as a substitute for charcoal in fuze powders. The N.I.P. fuze powders gave longer burning times and lower dispersions in M54 Time Fuzes under rotation and reduced pressure than the corresponding charcoal powders. They were also more sensitive to impact Ref D. Hart, Investigation of the Use of Nitroindene Polymer in Powder for M54 Time Fuze , PATR 1296 (1943) PATR 1525 (1945)... 

In connection with the burning time of chemical delay compns Eigsti and Dwiggins (Ref 16)... 

Tungsten Sample Lots Turbimeter Micromerograph Coulter Counter B.E.T. Burning Time sec/in... 

Since the foregoing tests were carried out at -identical conditions of compn and temp, and in a standard test fixture, the burning times serve as a means of checking the relative fineness of thea powdered tungsten fuels. The rapid burning times indicate that both M-10 and M-20 are very fine. Also, the M-10 is definitely finer than M-20, as shown by the difference in burning times... 

The specific surface being a gauge of the fineness of a powder, comparison of the result for M-10 and M-20 in Table 10 shows that the Turbidimeter yielded analyses which were consistent with the burning time data, that is, M-10 is a finer powder than M-20. The Micromero-graph showed a smaller difference between these two lots. The Coulter Counter gave results which were inconsistent with the burning times. It... 

Dwiggins, Particle Size Measurement and the Effect of Particle Size on The Burning Time of Chemical Delay Compositions , NAVWEPS 7304... 

A mixt of 50—80 parts of sulfamic ac and 50—20 parts of AP evolves copious amts of smoke on ign (Ref 20), A similar mixt of 390 parts of Zn oxide, 375 parts of hexachloroethane, and 190 parts of AP is slurried in a soln of 40 parts of polyvinyl acetate in 200 parts of mete chloride. The mixt is packed into cylinders, the solv evapu, and ignited to give copious amis of white smoke with a burning time of 68 secs (Ref 26) Refs 1) Gmelin, System No 23 (1936), 196 2) G.S. Serullas, AnnChimPhys (2) 46, 304... 

This was a problem to all the Allies but it was a Picatinny researcher who solved it. Thru patient burning of samples of cotton cloth, for burning time and amount of residual ash, he narrowed down the fabrics to a few good possibilities. Then he traveled to cotton mills in New England and the South to seek still better cloth. Finally a cotton fabric was developed as a suitable substitute for silk... 

Historically, storability, ignitibility and burn time have been recurring problems in tracer munition fabrication. The endothermic decompn of metal salt oxidizers and the brief exposure to the propint flame (0.5j-2msec) brought about the need for special igniters and... 

Mixture Application Mil Spec illustrative Composition Burn Time Range, sec/cm Temperature Coeff, %/°K r — Delay Time Change on Storage, sec/year-cm... 

Another consideration is the time duration of the thrust, or burn time of the motor. The burn time required is determined by the particular mission,... 

The only sure way to determine the burning time of any kind, or even roll, of safety fuse is to cut a measured length of it, light it, and time it. The operator can then select a length which will provide the time delay he desires. 

Test the burning time of several pieces of fuse of the same length, cut from the same roll. By counting slowly and steadily, as one thousand, two thousand, etc., from the moment the fuse is lit to the time the spark is observed at the other end, a uniform delay of 6 to 7 seconds should be observed. If identical lengths of identical fuse do not bum uniformly, that fuse should not be used for this technique. 

Figure 6. Effect of platinum on burning time and unburnt residue of silicone rubber containing 44 % silica.

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