- Smoke composition
A smoke composition is a
pyrotechnic composition designed primarily to generatesmoke . Smoke compositions are used as obscurants or for generation of signalling smokes. Some are used as a payload ofsmoke bomb s andsmoke grenade s.Obscurants
Smoke compositions used as obscurants generate large amount of thick, usually white, smoke. The most common smoke composition for pyrotechnic generation of
smoke screen s is the zinc chloride smoke mixture (HC).Zinc chloride smoke
Zinc chloride smoke is grey-white and consists of tiny particles of
zinc chloride . The most common mixture for generating these is the zinc chloride smoke mixture (HC), consisting ofhexachloroethane , grainedaluminium andzinc oxide . The smoke consists of zinc chloride, zinc oxychlorides, andhydrochloric acid , which absorb the moisture in the air. The smoke also contains traces of organic chlorinated compounds,phosgene ,carbon monoxide , andchlorine .Its toxicity is caused mainly by the content of strongly acidic hydrochloric acid, but also due to thermal effects of reaction of zinc chloride with water. These effects cause
lesion s of themucous membrane s of the upper airways. Damage of the lower airways can manifest itself later as well, due to fine particles of zinc chloride and traces of phosgene. In high concentrations the smoke can be very dangerous when inhaled. Symptoms includedyspnea , retrosternal pain,hoarseness ,stridor ,lachrymation ,cough ,expectoration , and in some caseshaemoptysis . Delayedpulmonary edema ,cyanosis orbronchopneumonia may develop. The smoke and the spent canisters contain suspectedcarcinogen s.The prognosis for the casualties depends on the degree of the pulmonary damage. All exposed individuals should be kept under observation for 8 hours. Most affected individuals recover within several days, with some symptoms persisting for up to 1-2 weeks. Severe cases can suffer of reduced pulmonary function for some months, the worst cases developing marked dyspnea and cyanosis leading to death.
Respirators are required for people coming into contact with the zinc chloride smoke.
ignalling
A
colored smoke composition can be used for signalling. These are usually based on a low-temperature burning pyrotechnic composition, mixed with adye that gets vaporized and creates large, colored smoke particles. The composition is often based on an oxidizer (e.g.potassium chlorate ,potassium nitrate , orpotassium perchlorate ), a fuel (e.g.lactose ), an optional coolant (e.g.sodium bicarbonate ), and one or more dyes.
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