Flame heated length

Stirring rods. These are made from glass rod 3-5 mm in diameter, cut into suitable lengths. Both ends should be rounded by heating in the Bunsen or blowpipe flame. The length of the stirring rod should be suitable for the size and the shape of the vessel for which it is employed, e.g. for use with a beaker provided with a spout, it should project 3-5 cm beyond the lip when in a resting position. 

This is identical with our result for the ignition time at a high heat flux in the thermally thin ignition of a solid. It can be generalized to say that flame speed - thermally driven -can be represented as the ratio of the flame extension length to the time needed to ignite this heated material, originally at 7). 

From 10 mm tube cut a 15 cm length and an 8 cm length. Fire-polish both ends of the long piece and only one end of the short one. Stopper one end of the 15 cm length and mark it in the centre. After a preliminary warm up in a soft flame, heat the mark with a hot flame, about half the diameter of the tube in size, and blow up a small blister similar to that shown in Fig. 6.29a. 

The sample solution is pumped (e.g., from the end of a liquid chromatographic column) through a capillary tube, near the end of which it is heated strongly. Over a short length of tube, some of the solvent is vaporized and expands rapidly. The remaining liquid and the expanding vapor mix and spray out the end of the tube as an aerosol. A flow of argon carries the aerosol into the plasma flame. 

The third characteristic of interest grows directly from the first, ie, the high thermal conductance of the heat pipe can make possible the physical separation of the heat source and the heat consumer (heat sink). Heat pipes >100 m in length have been constmcted and shown to behave predictably (3). Separation of source and sink is especially important in those appHcations in which chemical incompatibilities exist. For example, it may be necessary to inject heat into a reaction vessel. The lowest cost source of heat may be combustion of hydrocarbon fuels. However, contact with an open flame or with the combustion products might jeopardize the desired reaction process. In such a case it might be feasible to carry heat from the flame through the wall of the reaction vessel by use of a heat pipe. 

Metal deck assembhes are tested by UL for under-deck fire hazard by usiag their steiaer tunnel (ASTM E84). The assembly, exposed to an under-deck gas flame, must not allow rapid propagation of the fire down the length of the tuimel. FM uses a calorimeter fire-test chamber to evaluate the hazard of an under-deck fire. The deck is exposed to a gas flame and the rate of heat release is measured and correlated to the rate of flame propagation. A different FM test assesses the damage to roof iasulations exposed to radiant heat. 

The inlet duet must be of suffieient length to ensure eomplete eombus-tion and avoid direet flame eontaet on the heat transfer surfaees. 

For high-speed flames, which are usually accompanied hy a pressure rise, an array of apertures must have sufficient pressure drop to decelerate the flame, and sufficient length to achieve the heat loss needed to quench the flame. Thus, the diameter criterion is not sufficient and the effective length of the passageway must meet the following criterion (Wilson and Attalah 1975) ... 

A Combustion Tube of Hard Glass.—It should be about 13 mm. inside diameter, and the walls not more than i 5 mm. thick. Its length should be such that it projects at least 5 cm. (2 in.) beyond the furnace at either end. After cutting the required length, the ends of the tube are carefully heated in the flame until the sharp edges are just rounded. The tube is filled as follows. Push in a loose asbestos plug about 5 cm. (2 in.) from... 

Referring to Figure 7-72 at the calculated heat release, H., read the flame length, and refer to dimensional diagram for flame plume from a stack. Figure 7-73. 

Figure 7-72. Flame length versus heat release industrial sizes and releases (customary units). Reprinted by permission, American Petroleum Institute, API RP-521, Guide for Pressure Relieving and Depressuring Systems, 3rd Ed., Nov. 1990 [33].

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