Flash effects powders

Seawater Distillation. The principal thermal processes used to recover drinking water from seawater include multistage flash distillation, multi-effect distillation, and vapor compression distillation. In these processes, seawater is heated, and the relatively pure distillate is collected. Scale deposits, usually calcium carbonate, magnesium hydroxide, or calcium sulfate, lessen efficiency of these units. Dispersants such as poly(maleic acid) (39,40) inhibit scale formation, or at least modify it to form an easily removed powder, thus maintaining cleaner, more efficient heat-transfer surfaces. 

Nonel fuse, invented by Nitro Nobel AB in Sweden, consists of a thick plastic tube of bore about 1 mm, the inside surface of which is dusted with a small amount of powdered high explosive. If a shock wave is formed at one end of the tube the explosive powder is raised to a dust and a stable detonation at velocity 2000 m s 1 proceeds indefinitely along the fuse. The plastic itself is unaffected and the only outside effect is a flash of light seen through the tube walls. This therefore is an extremely safe method of propagating a detonation from one place to another. 

Dry chemical agents currently used are a mixture of powders, primarily sodium bicarbonate (ordinary), potassium bicarbonate (Purple K), monoammmonium phosphate (multipurpose). When applied to a fire they cause extinguishment by smothering the fire process. They will not provide securement of a flammable liquid spill or pool fire and it can re-flash after it is initially suppressed if an ignition source is present (i.e., a hot surface). Dry chemical is still very effective for extinguishment of three dimensional flammable liquid or gas fires. It is nonconductive and therefore can be used on live electrical equipment. 

In experimenting with fireworks, Roger Bacon and other medieval chemists discovered that a loose, open tray of powder was all that was needed to produce a flash, but in order to produce the bang the powder needed to be conhned, and this has great signihcance. And even with his unbalanced 6 5 5 formula. Bacon was able to deduce these fundamental ballistic effects. 

Non-explosive substance (e.g. vaseline) are added to nitroglycerine powders to reduce the heat of explosion and the temperature of the flash. The addition of cool explosives such as nitroguanidine has the same effect. 

Investigations showed that the salts of other alkali metals are not so efficient in suppressing secondary flame as potassium salts. Fairly numerous experiments were carried out to clear up whether or not known antiknock substances, such as tetraethyl lead or nickel carbonyl prevent the development of a secondary flame. They proved to have no effect on its development. In practice, two methods for removing gun-flash may be employed, i.e. either a special flashless powder is produced, containing nitroguanidine or DNT and a small admixture of potassium sulphate,... 

Bombshells are shot from mortars by means of a charge of black powder and burst high in the air with the production of reports, flashes, showers, and other spectacular effects. The smaller ones are shot from paper mortars the larger, most commonly from mortars of iron. In the past they have often been made in a spherical shape, wood or paper or metal hemispheres pasted heavily over with paper, but now in this country they are made almost exclusively in the form of cylinders. For the same caliber, cylindrical bombshells will hold more stars or other display material than spherical ones, and it is much easier to contrive them in a manner to procure multiple bursts. The materials of construction are paper, paste, and string. The shells are supplied with Roman fuses timed to cause them to burst at the top of their flight. The success and safety of bombshells depend upon carefully constructed fuses. 

Impact damage occurred to one of 48 10 kg polypropylene tubs of calcium hypochlorite, each closed with a polythene lid, all supported on a wooden pallet and stretch-wrapped round the base with polyethylene film. The spilled material was swept up and discarded, and the pallet was moved to another part of the warehouse, and some 30 mins, later flames were seen at the base of the pallet [1], Ignition was attributed to contact between residual solid hypochlorite on the pallet and lubricant drips on the concrete floor from fork lift traffic. Application of a dry powder extinguisher had little effect on the fire, but use of a 40 1 water extinguisher led to rapid escalation of the fire as contact between hypochlorite and wood was increased. Flash-over occurred and the fire eventually involved a considerable fraction of the 1400 t of assorted warehouse contents [2],... 

SAFETY PROFILE Confirmed carcinogen with experimental carcinogenic, neoplastigenic, and tumorigenic data. A deadly poison by intravenous route. Human systemic effects by inhalation lung fibrosis, dyspnea, and weight loss. Human mutation data reported. See also BERYLLIUM COMPOUNDS. A moderate fire hazard in the form of dust or powder, or when exposed to flame or by spontaneous chemical reaction. Slight explosion hazard in the form of powder or dust. Incompatible with halocarbons. Reacts incandescently with fluorine or chlorine. Mixtures of the powder with CCU or trichloroethylene will flash or spark on impact. When heated to decomposition in air it emits very toxic fumes of BeO. Reacts with Li and P. 

The w,causes electrochemical exchange between the Mg and the Ag ion. The heat of reaction of this exchange provokes the pyrochemical effect. I a peroxide oxidizes Mg powd with incandescence (Ref 5). The mixt explodes when Heated to redness. When the mixt is exposed to moist air spontaneous combustion occurs., When carbon dioxide gas is passed over a mixt of powd Mg and Na peroxide, the mixt explodes (Ref 6). Stannic oxide, heated with Mg, explodes (Ref 13)., A mixt of sulfates and Mg may cause an expln (Ref 17.) It has been detd experimentally that a mixt of Mg powd with trichloroethylene or carbon tetrachloride will flash or spark under, Heavy impact (Ref 2l). Mg alloy powders contg more than 50% Mg readily ignite in air (Ref 20)... 

Any theories about terrorists using sunglasses to offset the effect of these grenades are unfounded, as only the British S.A.S. have added a dash of flash powder to their Israeli-pattern grenades, and with nearly a half-pound of TNT already in these grenades their meager alteration may be well into the realm of diminishing returns. 

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