Dusts explosion behavior

Fire Hazards - Flash Point (deg. F) 350 OC Flammable Limits in Air (%) Not pertinent Fire Extinguishing Agents Water, foam, dry chemical, or carbon dioxide Fire Extinguishing Agents Not To Be Used No data Special Hazards of Combustion Products No data Behavior in Fire Dust explosion is high probability Ignition Temperature No data Electrical Hazard No data Burning Rate Not pertinent. 

The relative rarity of dust and powder ignitions makes them a unique sort of industrial safety threat. Because their occurrence is not routine, operating personnel eventually relax their guard, and too often this sort of behavior leads to dangerous incidents. The evidence that dust explosions are almost unknown within fluidized beds is an especially challenging problem for the safety officer, who must encourage vigilance even when no one remembers the last electrostatic incident. 

The subscript in vessel is for the reactor or building. The subscript experimental applies to data determined in the laboratory using either the vapor or dust explosion apparatus. Equation 6-20 allows the experimental results from the dust and vapor explosion apparatus to be applied to determining the explosive behavior of materials in buildings and process vessels. This is discussed in more detail in chapter 9. The constants KG and KSt are not physical properties of the material because they are dependent on (1) the composition of the mixture, (2) the mixing within the vessel, (3) the shape of the reaction vessel, and (4) the energy of the ignition source. It is therefore necessary to run the experiments as close as possible to the actual conditions under consideration. 

Dust explosions demonstrate unique behavior. These explosions occur if finely divided particles of solid material are dispersed in air and ignited. The dust particles can be either an unwanted by-product or the product itself. 

Dust explosions are even more difficult to characterize than gaseous explosions. For a gas the molecules are small and of well-defined size. For dust particles the particles are of varying size and many orders of magnitude larger than molecules. Gravity also affects dust particle behavior. 

Blowout panels are designed to provide the proper relief area, depending on a number of design factors. These include the explosive behavior of the dust or vapor, the maximum overpressure allowable in the structure, and the volume of the structure. Design standards are available.15... 

Extinguishing Agents Dry chemical, carbon dioxide, water fog, chemical foam Fire Extinguishing Agents Not To Be Used None Special Hazards of Combustion Products Not pertinent Behavior in Fire Vapor from molten benzoic acid may form explosive mixture with air. Concentrated dust may form explosive mixture in air Ignition Temperature (deg. F) 1,063 Electrical Hazard Not pertinent Burning Rate Not pertinent. 

The violence of the confined explosions (flammable v apor, gas, and dust) can be calculaled by the e.xplosion pressme mid energy eqmitions introduced earlier. The behavior of flammability (or e.xplosivity) limits of flammable mixtures and dusts is also covered in preceding sections. 

Hazards of Combustion Products. Data not available Behavior in Fire Melts and may decompose to give volatile acetic vapors pf valeric acid and other substances. Dust may form explosive mixture with air Ignition Temperature (deg. F) 788 Electrical Hazard. Not pertinent Burning Rate. Not pertinent. Chemical Reactivity Reactivity with Water No reaction Reactivity with Common Materials Data not available Stability During Transport Stable Neutralizing Agents for Acids and Caustics Rinse with dilute sodium bicarbonate or soda ash solution Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

CA 34, 3091 (1940) (Explosibility of 22 Coal dusts contg 8 to 31% volatile matter) M)W. Gassmann, Gliickauf 79, 369 77 (1943) (A review of firedamp explns caused in recent years by blasting in Dortmund mines) N)G.S.Scott, USBurMines Bull 455 (1944) CA 38, 6072 (1944) (Anthracite mine fires their behavior control) 0)A.van Tiggelen, Bull Belg 55, 202-44 (1946) CA 41, 4363 (1947) (Plate... 

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