Luminous flames

There is no satisfactory chemical way of distinguishing betn een ethane and methane, both of which burn with an almost non-luminous flame this fact however is quite unimportant at this stage of the investigation. Hydrogen also burns with a non-luminous flame and w hen the open end of a test-tube full of the gas is placed in a Bunsen flame, a mild explosion with a very characteristic report takes place. 

The Evolution of Methyl Iodide. The flask A (Fig. 89) is now heated with the non-luminous flame of the micro-burner. The immediate result of the heating will be an increase in the rate of bubbles passing up the absorption spiral no endeavour should be made to decrease this flow, however, as it will return to the original rate as soon as the hydro-... 

Assemble the apparatus shown in Fig. 1 V, 67, 1 this is self-explanatory. The distilling flask has a capacity of 250 ml. and the beaker contains 150 ml. of 10 per cent, sodium hydroxide solution. All corks must fit well and should be coated with paraflSn wax (by dipping into molten wax, and allowing to drain). Place half of the yield of the dry phenyldiazonium fluoborate in the distilling flask. Heat the solid gently with a small luminous flame at one point near its surface until decomposition begins withdraw the flame and allow the reaction to continue... 

Place 25 g. of methyl methacrylate polymer (G.B. Diakon (powder). Perspex (sheet) U.S.A. Lucite, Plexiglass) in a 100 ml. Claisen flask, attach an efficient condenser e.g., of the double smface type) and distil with a small luminous flame move the flame to and fro around the sides of the flask. At about 300° the polymer softens and undergoes rapid depolymerisation to the monomer, methyl methacrylate, which distils over into the receiver. Continue the distillation until only a small black residue (3-4 g.) remains. Redistil the hquid it passes over at 100-110°, mainly at 100-102°. The yield of methyl methacrylate (monomer) is 20 g. If the monomer is to be kept for any period, add 0 -1 g. of hydro quinone to act as a stabiUser or inhibitor of polymerisation. 

Furnaces for Oil and Natural Gas Firing. Natural gas furnaces are relatively small in size because of the ease of mixing the fuel and the air, hence the relatively rapid combustion of gas. Oil also bums rapidly with a luminous flame. To prevent excessive metal wall temperatures resulting from high radiation rates, oil-fired furnaces are designed slightly larger in size than gas-fired units in order to reduce the heat absorption rates. 

Luminous Flames Luminosity conventionally refers to soot radiation it is important when combustion occurs under such conditions that the hydrocarbons in the flame are subject to heat in the absence of sufficient air well mixed on a molecular scale. Because soot parti-... 

Many hydrocarbon flames are luminous because of the incandescent carbon particles formed in the flames. Under certain conditions, these particles are released from the luminous flames as smoke. Smoke from hydrocarbons is usually formed when the system is fuel rich, either overall or locally. 

A few crystals (or drop of solution) are heated in the non-luminous flame of a Bunsen burner. Melting with quiet burning is at one end of the spectrum cracking, flashing-off or flaring are considered hazardous. 

Combustion behavior differed in some respects between continuous and instantaneous spills, and also between LNG and refrigerated liquid propane. For continuous spills, a short period of premixed burning occurred immediately after ignition. This was characterized by a weakly luminous flame, and was followed by combustion of the fuel-rich portions of the plume, which burned with a rather low, bright yellow flame. Hame height increased markedly as soon as the fire burned back to the liquid pool at the spill point, and assumed the tilted, cylindrical shape that is characteristic of a pool fire. 

Properties.—Colourless, mobile liquid b.p. 35° sp. gr. 0720 at 15 burns with a luminous flame not miscible with water 9 parts of water dissolve i part of ether, and 35 parts of ether dissolve i part of water at the ordinary temperature. See Appoidix p. 236. 

Burners can be designed to produce a luminous flame by means of laminar mixing and partial cracking of the... 

Burners. The ordinary Bunsen burner is widely employed for the attainment of moderately high temperatures. The maximum temperature is attained by adjusting the regulator so as to admit rather more air than is required to produce a non-luminous flame too much air gives a noisy flame, which is unsuitable. 

To determine the exact Si02 content of the residue, moisten it with 1 mL water, add two or three drops of concentrated sulphuric acid and about 5 mL of the purest available hydrofluoric acid. (CARE ) Place the crucible in an air bath (Section 3.21) and evaporate the hydrofluoric acid in a fume cupboard (hood) with a small flame until the acid is completely expelled the liquid should not be boiled. (The crucible may also be directly heated with a small non-luminous flame.) Then increase the heat to volatilise the sulphuric acid, and finally heat with a Meker-type burner for 15 minutes. Allow to cool in a desiccator and weigh. Re-heat to constant weight. The loss in weight represents the weight of the silica (Note 2). 

Chemical Reactions. It burns with a luminous flame and is readily expld (Ref 2). It is reduced with Zn dust and Na hydroxide to dimethyl hydrazine (Ref 2). Action of coned HC1 forms methylhydrazine and formaldehyde (Ref 2). Treatment in anhyd eth with Na metal forms a solid adduct which gives dimethylhydrazine on addn of w (Ref 4). For a review of thermal and photochem reactions see Ref 8 Explosive Limits. In mixts with air the crit press at which exp] occurs varies inversely with temp betw 350 and 380° (Ref 6)... 

Paraffin (Paraffin wax. Hard paraffin). A mixt of solid hydrocarbons having the general formula CnH2n+2, obtained from petroleum. Colorl or white somewhat translucent, tasteless, odorless solid greasy feel bums with a luminous flame. 

Hubbard, G.L. and Tien, C.L., Infrared mean absorption coefficients of luminous flames and smoke, ASME. Heat Transfer, 100, 235,1978. 

Detection and Removal of Leaks and Holes Holes in awkward places are often difficult to find when one is assembling complex apparatus. If the joint in question is put in a luminous flame, or a flame put round the joint, and the apparatus blown into, the air will rush out of the holes and blow the flame away in a blue jet. The hole, when found, can then be repaired with thin glass rod (p. 58) or, if it is very big, it can often be filled in with a piece of glass. When a piece of glass falls out of an apparatus, it can be fused to a rod, to provide a handle, and put back again with the help of thin glass rod. 

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