Fire extinguisher, making

Most dry-chemical fire-extinguishing materials also function by inhibiting combustion rather than by cooling or by reducing oxygen concentration. The usual dry-chemical material is a bicarbonate, but some phosphates, eg, ammonium, provide a coating that makes the material suitable for use on fires involving soHd combustibles such as mbber tires, wood, and paper. 

Sodium bicarbonate- and borax bicarbonate-based dry chemicals were among the first dry agents used in portable fire extinguishers. About 1960, the sodium bicarbonate dry chemical was modified to make it compatible with protein-based, low-expansion foam to create a dual agent extinguishing system. Shortly thereafter, the more effective Purple K based extinguishers replaced sodium bicarbonate extinguishers. 

Uses. One of four common trihalomethanes formed after chlorination of water supplies in the past used to make fire extinguisher fluids. 

In discussing the extinguishing of fires, Sax makes the following remarks about metal fires ... 

Handle floor-plan questions in the same manner as those on maps. Before attempting to answer any questions, look at the diagram. Familiarize yourself with such features as doors, windows, doorways, patio doors, fire extinguishers, and smoke detectors. Read each question carefully then return to the diagram to find the answer. After you have determined your answer, try to match it to the choices. The correct answer should be apparent, but read each choice carefully to avoid making unnecessary errors. Never jump at one option without carefully reading all the others. 

Carbon tetrachloride commonly was employed as a cleaning solvent, although its considerable toxicity entails considerable hazard when used indiscriminately. It has been used as a fire-extinguishing fluid for petroleum fires, but its toxicity and tendency to form still more toxic carbonyl dichloride makes it undesirable for confined areas. The common laboratory practice of removing traces of water from solvents with metallic sodium should not be applied to halogenated compounds carbon tetrachloride-sodium mixtures are shock sensitive and can detonate. 

Sodium bicarbonate is widely used in the food industry, in making rubber in pharmaceuticals as an antacid in fire extinguishers, soap and detergents, rug cleaners, animal feeds, and textiles in leather preparation in soap, detergent, and paper manufacturing for flue-gas scrubbing and for many other diversified small-scale uses. 

Make sure you know where safety devices such as eye bath, fire extinguisher, first aid kit are kept before you start work in the lab. 

Chloroform is a volatile, low-molecular weight, lipophilic compound and a chlorinated trihalo-metheane. Most of the chloroform produced in the United States is used to make fluorocarbon 22 (HCFC 22) and the rest is produced for export and miscellaneous uses. In the past it was used as an inhalation anesthetic and as an extraction for, fats, oils, greases and other products, as a dry cleaning spot remover, in fire extinguishers, and as a fumigant. It is available as emulsions, spirits, tinctures, and chloroform water. Chloroform is also formed as a by-product of chlorination of water, wastewater, and swimming pool. Other sources include pulp and paper mills, hazardous waste sites, and sanitary landfills. 

Use Dry-cleaning solvent, fire extinguishers, to make chlorotrifluoroethylene, blowing agent, polymer intermediate, solvent drying, drying electronic parts and precision equipment. 

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