Fire Extinguishment

If a flammable gas or vapour is present, a pre-fire condition may be identified by a flammable-gas detector. Fire detection may be by  

A combination of detectors may be appropriate. They may activate an alarm only, or actuate a combined alarm/extinguishment system. 

Removal of one of the corners of the fire triangle normally results in extinguishment of a fire. Propagation of a flame can also be stopped by inhibition of the chain reactions, e.g. using dry powders or organo—halogen vaporizing liquids. 

A Fire involving solid materials, generally organic materials, in which combustion 

B Fire involving a liquid or liquefiable solid (the miscibility or otherwise with 

The specific heat of water is important because it is so high in relation to the specific heat of other materials this fact means that it takes more energy to raise the temperature of water than just about any other material. Therefore, the temperature of the materials to which water has been applied will drop faster than the temperature of water will rise. The specific heat may be reported as die number of calories needed to raise the temperature of one gram of the material 1°C, or the number of British Thermal Units (BTUs) needed to raise one pound of the material, 1°F. Therefore, when water is applied to a fire, it begins absorbing heat from die fire, thereby cooling the fire down while the water heats up. For every BTU absorbed, the temperature of the water will rise 1°F per 

of course, does not work with all materials. There is a special class of materials that are water reactive, and hence water becomes an unacceptable extinguishing agent. For these class of materials another approach to eliminating the fire is taken. Specifically, we must remove the oxidizer leg from the fire triangle i.e. cut off the supply of oxygen which fuels the air to fuel mixture. 

Segregation of the material from other chemicals, particularly fuels , i.e. solvents, paper, cloth etc. 

Handling in dry, chemically inert atmospheres or beneath other appropriate media, e.g. dry oil or inert gas. 

Handling in solution (e.g. aluminium alkyls in petroleum solvents). 

Careful selection and provision of appropriate fire extinguishers in advance. Provision and use of appropriate eye/face protection, overalls and gloves. 

Substitute with less volatile/flammable material where possible (i.e. higher flash point/autoignition temperature, lower vapour pressure) 

Check on legal requirements and relevant standards/codes etc. 

Keep below LEL, e.g. chill to lower airborne concentration, use exhaust ventilation, inerting, keep air out. 

Design plant/equipment so as to contain the material and provide adequate dilution or exhaust ventilation as appropriate 

Provide means to contain spillages, e.g. bund walls, kerbs Eliminate ignition sources 

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Most of the trichloroethylene produced is used for metal degreasing. Other important uses are in the scouring of wool and as an extractive solvent, e.g. for olive and soya bean oils. Minor uses are as a heat transfer medium, anaesthetic, insecticide and fumigant, paint remover and fire extinguisher. 

Carbon dioxide is used in the manufacture of sodium carbonate by the ammonia-soda process, urea, salicyclic acid (for aspirin), fire extinguishers and aerated water. Lesser amounts are used to transfer heat generated by an atomic reactor to water and so produce steam and electric power, whilst solid carbon dioxide is used as a refrigerant, a mixture of solid carbon dioxide and alcohol providing a good low-temperature bath (195 K) in which reactions can be carried out in the laboratory. 

Sand. Buckets of dry sand for fire-extinguishing should be available in the laboratory and should be strictly reserved for this purpose, and not encumbered with sand-baths, waste-paper, etc. Most fires on the bench may be quickly smothered by the ample use of sand. Sand once used for this purpose should always be thrown away afterwards, and not returned to the buckets, as it may contain appreciable quantities of inflammable, non-volatile materials e.g., nitrobenzene), and be dangerous if used a second time. 

Carbon tetrachloride must not be dried with sodium as an explosion may result. Fire extinguishers containing this solvent (e.g., Pyrene ) cannot therefore be applied to a fire originating from sodium. 

Finally, the student should familiarise himself with the contents of the Section in the Appendix upon Laboratory Accidents, with the position of the fire extinguisher, buckets of sand, first aid cabinet, and the fireproof blanket. 

It is usually better to use a fire extinguisher charged with carbon dioxide under pressure this produces a spray of solid carbon dioxide upon releasing the pressure intermittently and is effective for extinguishing most fires in the laboratory. 

Fire control Fire damp Fired heaters Fire extinguishants Fire extinguisher Fire extinguishers... 

Production and Shipment. Estimated adiponitrile production capacities in the U.S. in 1992 were about 625 thousand metric tons and worldwide capacity was in excess of lO metric tons. The DOT/IMO classification for adiponitrile is class 6.1 hazard, UN No. 2205. It requires a POISON label on all containers and is in packing group III. Approved materials of constmction for shipping, storage, and associated transportation equipment are carbon steel and type 316 stainless steel. Either centrifugal or positive displacement pumps may be used. Carbon dioxide or chemical-foam fire extinguishers should be used. There are no specifications for commercial adiponitrile. The typical composition is 99.5 wt % adiponitrile. Impurities that may be present depend on the method of manufacture, and thus, vary depending on the source. 

Shipment. The DOT/IMO shipping information is shown in Table 6. Approved materials of constmction for shipping, storage, and associated transportation equipment are lined carbon steel (DOT spec. 105 S 500W) and type 316 stainless steel. Water spray, carbon dioxide, chemical-foam, or dry-chemical fire extinguishers may be used. 

In this sequence the Cl also acts as a catalyst and two molecules are destroyed. It is estimated that before the Cl is finally removed from the atmosphere in 1—2 yr by precipitation, each Cl atom will have destroyed approximately 100,000 molecules (60). The estimated O -depletion potential of some common CFCs, hydrofluorocarbons, HFCs, and hydrochlorofluorocarbons, HCFCs, are presented in Table 10. The O -depletion potential is defined as the ratio of the emission rate of a compound required to produce a steady-state depletion of 1% to the amount of CFC-11 required to produce the 1% depletion. The halons, bromochlorofluorocarbons or bromofluorocarbons that are widely used in fire extinguishers, are also ozone-depleting compounds. Although halon emissions, and thus the atmospheric concentrations, are much lower than the most common CFCs, halons are of concern because they are from three to ten times more destmctive to O, than the CFCs. 

Sodium Bicarbonate. Many soda ash plants convert a portion of their production to sodium bicarbonate [144-55-8], NaHCO. Soda ash is typically dissolved, carbonated, and cooled to crystallize sodium bicarbonate. The mother Hquor is heated and recycled. The soHd bicarbonate is dried in flash or tray driers, screened, and separated into various particle size ranges. Bicarbonate markets include food, pharmaceuticals, catde feed, and fire extinguishers. U.S. demand was approximately 320,000 t in 1989 world demand was estimated at one million metric tons. 

H-1211 fire extinguishant HCFC-123 HBFC-22B1 HBFC-124B1 PFC-51-14 HFCs... 

C. N. Fletcher, P. Jones, and M. Winterton, "Clean Agent Fire Extinguishant Break-Down Products," 1990 International Conference on CEC and Hahn Altematipes, Baltimore, Md., 1990. 

Industrial Applications. Perfluoroacylbenzene sulfonates, used as additives in fire-extinguishing compounds and galvanizing baths have been prepared (88). Perfluoroacylbenzenesulfonate salts prepared by Friedel-Crafts reaction of perfluoroacyl haUdes and benzene, and subsequent sulfonation have been used as surfactants (89). 

Storage areas for maintenance, janitorial, and other service organizations must be provided. Safety items such as fire extinguishers, firehose cabinets, safety hoops on permanent ladders, guard rads, shielding for acid pumps, clearance for electric panel boards, etc, are needed. Manholes and cleanouts for sewer pipes within the facility as well as in the landscape and parking areas should be provided. 

Underwriters Laboratories 333 Pfingsten Road Northbrook, Id. 60062 Standards for Safety is ahst of more than 200 standards that provide specifications and requirements for constmetion and performance under test and in actual use of a broad range of electrical apparatus and equipment, including household appHances, fire-extinguishing and fire protection devices and equipment, and many other nongenerady classifiable items, eg, ladders, sweeping compounds, waste cans, and roof jacks for trader coaches. 

Some dry-chemical fire extinguishers contain sodium or potassium bicarbonate these should not be used on nitromethane or nitroethane fires. Dry chemical extinguishers can be used on nitropropane fires. 

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