Extinguishing gases

Two newer extinguishing gases are available Ineigen is a gas mixture designed to flood an area but be breathable for a short time FM 200 is an extinguisher gas which is also friendly to the ozone layer. There is also a Finnish water micromist system which can replace inert gas in some applications. 

Hospitals and dental surgeries (anaesthetic gases), indusirial sites, laboratories, mines. Victims found in bathrooms, boats, caravans, cars, fires, kitchens Presence offire extinguishers, gas fiies,geyseis, portable heaters... 

Another TIP shot struck her armour, diffracting. A wide splash of skin on the dead man veered to a rancid bmised-brown as the energy punched it. His clothes were smouldering, drawing the extinguisher gas like a condensing dew. 

Gas systems contain an extinguishant gas at high pressure supplied from gas cylinders. 

A colourless gas, b.p. — 59-C/740 mm. Used as a relatively non-toxic propellant gas in fire fighting apparatus, e.g. dry-powder extinguishers. Made by the bromination of fluoro-form, CHF3. 

The two major difficulties facing the analyst/mass spectrometrist concern firstly how to get the whole of the sample into the plasma flame efficiently and secondly how to do so without destabilizing or extinguishing the flame. Although plasma flames operate at temperatures of 6000 to 8000 K, the mass of gas in the flame is very small, and its thermal capacity is correspondingly small (Figure 15.1). 

Fire Hazard. Although chlorosulfuric acid itself is not dammable, it may cause ignition by contact with combustible materials because of the heat of reaction. Open fires, open lights, and matches should not be used in or around tanks or containers where hydrogen gas may be collected because of the action of chlorosulfuric acid on metals. Water, carbon dioxide, and dry-chemical fire extinguishers should be kept readily available. 

Foam Production This is important in froth-flotation separations in the manufac ture of cellular elastomers, plastics, and glass and in certain special apphcations (e.g., food products, fire extinguishers). Unwanted foam can occur in process columns, in agitated vessels, and in reactors in which a gaseous product is formed it must be avoided, destroyed, or controlled. Berkman and Egloff (Emulsions and Foams, Reinhold, New York, 1941, pp. 112-152) have mentioned that foam is produced only in systems possessing the proper combination of interfacial tension, viscosity, volatihty, and concentration of solute or suspended solids. From the standpoint of gas comminution, foam production requires the creation of small biibbles in a hquid capable of sustaining foam. 

Figure 19.3 Theory of ionization and deionization of gas atoms to extinguish the arc plasma...

As the moving contact moves away, so the arc plasma elongates, losing its initial intensity, and as it approaches the current zero, it loses the most of it. The gas, on the other hand, cools and regains its lost mass, while its pressure in the chamber continues to build to its optimum level, making it more capable of extinguishing a less severe arc plasma. The interrupter can thus be adjusted to blow out the arc at the first current zero, while clearing heavy to very heavy fault currents. 

Dry powders are effeetive on flammable liquid or eleetrieal fires. Speeial powders are available for use on metals. Dry powder extinguishers may be used on Class C fires, ineluding gases and liquefied gases in the form of a liquid spillage or a liquid or gas leak. This must be aeeompanied by other aetions, e.g. stopping the leak this is neeessary to avoid aeeumulation of an unburned flammable gas-air mixture whieh eould subsequently result in an explosion. Aetivation may be automatie by a deteetion system, or manual. 

Liquid carbon dioxide is discussed on page 261. Carbon dioxide gas is commonly used for carbonating drinks, in fire extinguishers, for gas-shielding of welding and in shell moulding in foundries. Its physical and toxicological properties are summarized in Tables 8.5, 8.6 and 5.29. 

Eire protection - Eire extinguishing media - Elalogenated hydrocarbons. Code of practice for safe handling and transfer procedures. Supersedes BS 6535 Section 2.2 1989 Water quality - Gas chromatographic determination of some selected chlorophenols m water. Also BS 6068-2.65 1999... 

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