Of smoke

Secondary smoke is produced mosdy by the condensation of water in humid or cold air. The presence of hydrogen chloride or hydrogen fluoride in the combustion products increases the extent and rate of condensation. Composition modifications to reduce primary smoke may reduce secondary smoke to some extent, but complete elimination is unlikely. The relatively small amount of smoke produced in gun firings by modem nitrocellulose propellants, although undesirable, is acceptable (102—109). 

H. K. Hasegawa, Characterisation and Toxicity of Smoke, Pubhcation STP 1082, American Association for Testing and Matedals, Philadelphia, Pa., 1990. 

Lead is absorbed into the human body after inhalation of the dust or ingestion of lead-containing products. Contamination of smoking materials in the work area leads to inhalation of lead fumes and constitutes a main factor in lead absorption. 

Kerosene is beheved to be composed chiefly of hydrocarbons containing twelve to fifteen carbon atoms per molecule. Low proportions of aromatic and unsaturated hydrocarbons are desirable to maintain the lowest possible level of smoke during burning. Although some aromatics may occur within the boiling range assigned to kerosene, excessive amounts can be removed by extraction. 

MSTM D2843, Test Method for Density of Smoke from the Burning or Decomposition of Elastics., Vol. 8.02, ASTM, Philadelphia, Pa., 1993. 

Another type of smoke mixture, a volatile hygroscopic chloride for thermal generation, has the U.S. Army designation HC, type C. It is composed of ca 6.7 wt % grained aluminum, 46.7 wt % zinc oxide ZnO, and 46.7 wt % hexachloroethane [67-72-17, The ratio of zinc oxide to... 

Although a number of low temperature processes have been studied, only a few have been used commercially. These have been limited in the types of coal that are acceptable, and the by-products are less valuable than those obtained from high temperature processing. The Disco process is used in the United States to supply a limited amount of fuel to meet requirements of smoke ordinances. The British CoaUte and Rexco processes produced substantial amounts of domestic smokeless fuel. Development of fluid-bed methods of carbonizing finer coal at ca 400°C has been studied in the United Kingdom. A reactive char is briquetted without a binder to produce a premium open-fire smokeless fuel. 

With the increasing emphasis on energy conservation and environmental considerations, additives for fuels that can correct combustion-related problems have aroused considerable interest. Many commercial fuel additives are combinations of organometaHics, dispersants, emulsifiers, and carrier solvents. The organometaHic, often a metal soap, acts as a combustion catalyst, increasing efficiency with reduction of smoke, deposits, and corrosion. 

Compared to optical photography. X-rays have the distinct advantage that they see through opaque clouds of smoke and debris. Most materials can also be penetrated by the appropriate high-energy X-rays, making internal voids in materials, such as incipient spalls, clearly visible. 

By 1819, there was sufficient pressure for Parliament to appoint the first of a whole dynasty of committees "to consider how far persons using steam engines and furnaces could work them in a manner less prejudicial to public health and comfort." This committee confirmed the practicability of smoke prevenfion, as so many succeeding committees were to do, but as was often again to be experienced, nothing was done. 

An air pollution episode responsible for approximately 300 excess deaths occurred in London between November 26 and December 1, 1948. Concentrations of smoke and sulfur dioxide were 50-70% of the values during the 1952 episode. 

Gas velocihes can also be measured with anemometers (rotating vane, hot wire, etc.), from visual observations such as the velocity of smoke puffs, or from mass balance data (knowing the fuel consumption rate, air/ fuel ratio, and stack diameter). 

Over the years plastics users have demanded progressively improving fire performance. By this is meant that plastics materials should resist burning and in addition that levels of smoke and toxic gases emitted should be negligible. That a measure of success has been achieved is the result of two approaches ... 

Records show that more fatalities occur through victims being suffocated by smoke or poisoned by toxic gases emitted during a fire than by being burnt to death. This is particularly worrying when it is realised that many additives incorporated into a polymer to retard its flammability are often found to increase the amount of smoke emitted as the rate of flame propagation decreases. Most... 

The use of fire retardants in polymers has become more complicated with the realisation that more deaths are probably caused by smoke and toxic combustion products than by fire itself. The suppression of a fire by the use of fire retardants may well result in smouldering and the production of smoke, rather than complete combustion with little smoke evolution. Furthermore, whilst complete combustion of organic materials leads to the formation of simple molecules such as CO2, H2O, N2, SO2 and hydrogen halides, incomplete combustion leads to the production of more complex and noxious materials as well as the simple structured but highly poisonous hydrogen cyanide and carbon monoxide. 

Polyurethane foams do, however, suffer from one serious disadvantage. Unless modified they bum with copious evolution of smoke and toxic by-products, which has led to a number of fatal fires, particularly in domestic accommodation. To some extent the problem may be reduced by suitable upholstery covering, but as mentioned on p. 775 a number of countries have now made mandatory the use of fire retardent additives. At the time of writing there is considerable activity in the development of new safer systems, particularly in the use of amino materials such as melamine as additives. Further developments may also be expected in the near future. 

Prohibition of smoking, carrying matches/lighters, except in designated areas ... 

Determination of smoke emission from manufactured solid fuels for domestic use. Part 1 General method for determination of smoke emission rate. Superseded BS 3841 1972 Determination of smoke emission from manufactured solid fuels for domestic use. Part 2 Methods for measunng the smoke emission rate. Superseded BS 3841 1972... 

Withdrawn) 1974 AMD 1 Laboratory methods of test for determination of smoke generation charactenstics of cellular plastics and cellular rubber materials. Part 1 Method for testing a 25 mm cube test specimen of low density material (up to 130 kg/metres cubed) to continuous flaming conditions (AMD 7688) dated 15 July 1993. Withdrawn, superseded by BS ISO 5659-2 1994... 

Withdrawn) 1974 AMD 1 Laboratory methods of test for determination of smoke generation charactenstics of cellular plastics and cellular rubber materials. Superseded by BS ISO 5659-2 1994... 

Sets out ancillary controls related to air pollution control including regulation of smoke, grit, dust and fume emissions from non-prescnbed mdustnal processes provision of a lower level of control over some smaller combustion plants not covered by IPC or LAAPC prohibition of the emission of dark smoke from any chimney or industrial premises. 

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