Emission smoke

One of the major applicahons of pyrolants is to produce smoke clouds or smoke curtains by chemical reactions.I -s] Smoke is defined as condensed particles that can remain in the atmosphere for at least several seconds. The radiative emission from smoke itself is small because of its low-temperature nature. Thus, no visible emission is seen in the dark by the human eye. The applications of smoke are  

In general, the chemicals used to create color displays in the daytime are various types of dyes and oils. Though dyes and oils do not fall into the category of pyrolants that generate colored smoke by combustion reactions, they are dispersed in the atmosphere by the combustion or decomposition gases of pyrolants. Typical examples of color dyes are indigo for blue, rhodamine for red, and auramine for yel- 

The temperature of the gases produced by the reaction between KCIO3 and S is low enough to prevent burning in air. A mass fraction of NaHC03 of approximately 0.2 is also incorporated as a coolant that prevents a flame reaction between the dyes and 

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The industrial value of furfuryl alcohol is a consequence of its low viscosity, high reactivity, and the outstanding chemical, mechanical, and thermal properties of its polymers, corrosion resistance, nonburning, low smoke emission, and exceUent char formation. The reactivity profile of furfuryl alcohol and resins is such that final curing can take place at ambient temperature with strong acids or at elevated temperature with latent acids. Major markets for furfuryl alcohol resins include the production of cores and molds for casting metals, corrosion-resistant fiber-reinforced plastics (FRPs), binders for refractories and corrosion-resistant cements and mortars. 

Corrosion Resistant Fiber-Reinforced Plastic (FRP). Fiber glass reinforcement bonded with furfuryl alcohol thermosetting resias provides plastics with unique properties. Excellent resistance to corrosion and heat distortion coupled with low flame spread and low smoke emission are characteristics that make them valuable as laminating resins with fiber glass (75,76). Another valuable property of furan FRP is its strength at elevated temperature. Hand-layup, spray-up, and filament-win ding techniques are employed to produce an array of corrosion-resistant equipment, pipes, tanks, vats, ducts, scmbbers, stacks, and reaction vessels for industrial appHcations throughout the world. 

Military Application and Aerospace Wires. Depending on the specific appHcation, a variety of polymers can be considered PVC, polyamides, PTEE, etc (Eig. 3). Navy shipboard specifications require cables with dame retardancy, low smoke emission during fire, and containing no halogen. 

Ethylene vinyl acetate (EVA) polymers are used in thermoplastic and thermosetting jacketing compounds for apphcations that require flame retardancy combined with low smoke emission during the fire as well as the absence of halogen in the composition. 

Udel is a slightly yellow but tianspaient engineering thermoplastic. It has low flammability and smoke emission and good electrical properties. It has excellent resistance to water, steam, and alkaline solutions. Specific uses for Udel iaclude microwave cookware, beverage dispensers, coffee brewers, cookware, hair dryers, com poppers, and steam table trays. Its steam resistance makes it particularly fit for a dishwasher environment. Properties of polysulfone resias ate given ia Table 11. 

The PEEK resia is gray, crystalline, and has excellent chemical resistance T is ca 185°C, and it melts at 288°C. The unfilled resia has an HPT of 165°C, which can be iacreased to near its melting poiat by incorporating glass filler. The resia is thermally stable, and maintains ductiUty for over one week after being heated to 320°C it can be kept for years at 200°C. Hydrolytic stabiUty is excellent. The resia is flame retardant, has low smoke emission, and can be processed at 340—400°C. Crystallinity is a function of mold temperature and can reach 30—35% at mold temperatures of 160°C. Recycled material can be safely processed. Properties are given ia Table 16. 

Other examples of trends come from Great Britain, where the emission of industrial smoke was reduced from 1.4 million tonnes per year in 1953 to 0.1 million tonnes per year in 1972 domestic smoke emission was reduced from 1.35 million tonnes per year in 1953 to 0.58 million tonnes per year in 1972 and the number of London fogs (smogs) capable of reducing visibility at 9 AM to less than 1 km was reduced from 59 per year in 1946 to 5 per year in 1976. 

Limits on emissions are both subjective and objective. Subjective limits are based on the visual appearance or smell of an emission. Objective limits are based on physical or chemical measurement of the emission. The most common form of subjective limit is that which regulates the optical density of a stack plume, measured by comparison with a Ringelmann chart (Fig. 25-1). This form of chart has been in use for over 90 years and is widely accepted for grading the blackness of black or gray smoke emissions. Within the past four decades, it has been used as the basis for "equivalent opacity" regulations for grading the optical density of emissions of colors other than black or gray. 

Balir, D.W., Smith, J.R., and Kenwortliy, N.J., Development of Low Smoke Emission Combustors for Large Aircraft Turbine Engines, AIAA Paper Number 69-493. 

Very low smoke emission, superior even to polyethersulphone. 

Extremely low smoke emission. PEEK has been claimed to have the lowest toxic gas and smoke emissions of any plastics material. 

Low smoke emission (roughly comparable to that of a polycarbonate). Very low coefficient of thermal expansion in the flow direction (0-15 cm/ cm/°C) but correspondingly higher in the transverse direction (27-76 cm/ cm/°C). 

Not only does the material have excellent resistance to burning but smoke emission values are reported to be much less than for fire-retardant polyester resin. The laminates are being increasingly used in situations where corrosion is associated with organic media, where corrosion is encountered at temperatures above 100°C as in fume stacks and where both fire retardance and corrosion resistance are desired as in fume ducts. 

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... 

FIRE SIMULATOR predicts the effects of fire growth in a 1-room, 2-vent compartment with sprinkler and detector. It predicts temperature and smoke properties (Oj/CO/COj concentrations and optical densities), heat transfer through room walls and ceilings, sprinkler/heat and smoke detector activation time, heating history of sprinkler/heat detector links, smoke detector response, sprinkler activation, ceiling jet temperature and velocity history (at specified radius from the flre i, sprinkler suppression rate of fire, time to flashover, post-flashover burning rates and duration, doors and windows which open and close, forced ventilation, post-flashover ventilation-limited combustion, lower flammability limit, smoke emissivity, and generation rates of CO/CO, pro iri i post-flashover. 

Carbon residue is expressed as a percentage by weight of the original sample of the fuel, with the amount determined by burning a given quantity in a scaled container until all that remains is carbon residue. The amount of carbon residue left within the combustion chamber of the engine has a direct bearing upon the internal deposits and affects the cleanliness of combustion, particularly the smoke emissions at the exhaust stack. 

Commercial and industrial H V applications and where Class O fire rating and low smoke-emission characteristics are required. 

Low smoke emission is also often associated with a high carbon hydrogen ratio. Table 18.15 gives some collected data for the limiting oxygen index. 

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