Toxic smoke generation

All these polymers incorporate high halogen levels that are environmentally harmful. PTFE creep and abrasion sensitivity injection and extrusion are impossible by conventional processes high dimensional variation at glass transition temperature (19°C) high cost high density very difficult to stick corrosive and toxic smoke generated in fires. 

This defensive work included improvements to many First World War weapons, including gas shells, mortar bombs, the Livens Projector and toxic smoke generators and the development of apparatus for mustard gas spray from aircraft, bombs of many types, airburst mustard gas shell, gas grenades and weapons for attacking tanks . The various inventions were tested in north Wales, Scotland, and in installations scattered throughout the Empire, notably northern India, Australia and the Middle East. 

Various chemicals and their crude mixtures were used in the wars in many parts of the world all throughout history. In the fifth century BC Spartan used toxic smoke generated from burning wood dipped in a mixture of sulfur and tar against Athens. Early Chinese manuscripts in the fourth century BC indicate the use of toxic smokes from cacodyl (arsenic trioxide). Chemicals of incendiary compositions, such as, sulfur, pitch and sawdust and oil-based incendiaries slowly attained wider applications in the latter wars. 

In recent years, environmental concerns over toxic smoke generation during fire and end-of-life incineration of electronic equipment containing brominated... 

In addition to the inherent flame resistance, the polymers are also interesting because of the low smoke generation and low levels of toxic and corrosive emissions when exposed to fire. 

These materials are developed from the polyetherimides introduced by General Electric (see also Section 18.14.2). At the time of writing one grade, Ultem Siltem STM 1500, is being offered. It is of particular interest as a material for wire and cable insulation, as it not only has excellent flame resistance coupled with low smoke generation but also avoids possible toxic and corrosion hazards of halogenated polymers. This can be of importance where there are possible escape problems in the event of a fire, such as in tunnels, aircraft and marine (particularly submarine) vessels. 

Smoke is not a uniform substance and its composition depends on the exact conditions under which it was generated. Therefore, the composition of the smoke generated from the same material in different tests can vary broadly and, consequently, so will its toxicity. 

In 1978, the Home Office report (14) concerning the fire behaviour of new (i.e. post 1945) materials specifically criticised the fire performance of upholstered domestic furniture and recommended manufacturers to improve ignition resistance, to reduce flammability, and to reduce the rates of smoke and toxic gas generation. 

Because of the lack of suitable standard rate of heat, smoke and toxic gas generation tests, the 1988 UK regulations are based on ignition resistance of individual materials. This contradicts the basic requirements for the fire testing of composites and of hazard related tests and as such it may be possible to develop materials which meet the requirements but which produce hazardous products. 

Fires starting in a room may eventually get transferred to a plenum above it. However, by the time the effects of such a fire cause PVC products (rigid conduit, ENMT conduit and wire coating) in the plenum to burn, the room has already reached flashover conditions. Furthermore, the smoke generated by the room fire fuel causes much faster toxic concern than that from the PVC products in the plenum. 

Smoke or toxic vapor generation (when life safety is associated with protection)... 

CA 86, 51210 (1977) [The toxic effect of PVC combstn products on the human organism was evaluated and the Toxic Threshold Level is reported as 0.3g of PVC products/M3 of air] 2) M. Bert et al, Reduction of Smoke Generation in Poly (Vinyl Chloride) Combustion , FireRes (4-5), 301-11 (1978) CA 90,72796 (1979) [The authors report that the most efficient (toxic) smoke suppressors for PVC are those which show catalytic activity in oxidation reactions, such as Cu, Fe, or V compds. These suppressors cause incandescence and complete combstn of the solid residue without excessive smoke prodn. They conclude that their efficiency is not very dependent on the anion bound to the metal, but may depend on the temp] 3) E A. Harrison, Toxicity of Vinyl... 

Both by application and by geography, fire safety standards are highly diverse and complex. Some standards tend to focus primarily on preventing ignition and flame spread, while others put additional emphasis on reducing smoke generation and toxic/corrosive by-products from burning wires and cables. 

Numerous special chemical de ices such as land mines, toxic smoke candles, smoke generators on tanks, etc., have also been developed during the postwar period by many of the principal world powers. 

Extrusion grade, PEI/PC blend was developed for aircraft applications to meet the federal aviation standards for low flammability, smoke and toxic gas generation [Skeist, 1991]. PEEPC ther-moformable sheet is used for the fabrication of transport aircraft window housings, air ducts, consoles and other components. PEI/PC sheet is also used as high temperamre paint mask in the automotive industry. PEI/PC molding compounds have also been evaluated for microwave-able cookware. Due to the high cost of PEI,... 

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