Spontaneous combustion point

According to the National Board of Fire Underwriters, activated carbons normally used for water treatment pose no dust explosion ha2ard and are not subject to spontaneous combustion when confined to bags, dmms, or storage bins (64). However, activated carbon bums when sufficient heat is appbed the ignition point varies between about 300 and 600°C (65). 

The fuels consumed in the fire were treated wood, penta, and creosote (coal tars). Both are considered combustible liquids, with flash points above 160° F (CC). Vapor conditions within the headspaces of tanks can, however, reach explosive conditions, and the introduction of an ignition source resulted in spontaneous combustion. Under ideal conditions, creosote burns similar to crude oil, and in standard lab burn tests, has an average burn rate of 4 mm/min. There is no data on the burn rate of penta however, its vapors would have likely burned at much slower rates and a series of complex chemical transformations would have occurred. 

The flash point of an oil is the temperature at which it gives off, under specified conditions, sufficient vapor to form a flammable mixture with air. This is very different from the temperature of spontaneous combustion. The test is an empirical one and the result depends upon the instm-ment used and the prescribed conditions. For example, the flash point may be closed or open , depending on whether the test apparatus has a lid or not. As far as lubricating oils are concerned, the test is of limited significance, although it can be indicative of contamination (for example, the dilution of crankcase oil by fuel). 

Capable of igniting and burning in air without the presence of an ignition source. Pyrophoric materials are spontaneously combustible, although some pyrophorics require the presence of a minimum amount of moisture (humidity) to spontaneously ignite. Other spontaneously combustible substances and mixtures may require more time or an insulating environment to self-heat to the point of ignition. 

Another test (ASTM E-659) is available that can be used as a complement to the flash point test and involves determination of the autoignition temperature. However, the flash point should not be confused with the autoignition temperature, which measures spontaneous combustion with no external source of ignition. 

Spontaneously Combustible The process of increase in temperature of a material to a point of ignition without drawing heat from its surroundings. 

W. Braker, A.L. Mossman, Matheson Gas Data Book, Matheson Gas Products, East Rutherford 1971, p. 301. Ihave left out some of the less interesting dimensions in this connection heat capacity (20.9°C) 2.625 J g 1 K 1 (Water 4.187 J g 1 K 1) dielectricity constant (20°C) 114 (Water=78.5) evaporation heat 28 kJ mol"1 evaporation entropy 190 J mol"1 K"1 spontaneous combustion temperature 538°C flash point -17.8°C regarding dielectricity constants, see R.C. Weast (ed.), Handbook ofChemistry and Physics, 66th Ed., CRC Press, Boca Raton, Florida 1986, E 40. However, under normal conditions (1 atm, 25°C), hydrogen cyanide is not a gas. 

The ignition point (or auto-ignition point) is used as an index of the spontaneous combustibility of a flammable gas in air. The ignition point is the lowest temperature at which ignition can occur by heating a flammable gas in an atmosphere which will support combustion in the absence of an ignition source such as a flame or electric... 

Spontaneous combustion can arise from exothermic chemical reactions of some materials, e.g., with water, or through the action of microorganisms. Microorganism growth can heat a medium to about 70°C where, although the heat is sufficient to kill the microorganisms, the increased temperature may be sufficient to rapidly increase the rate of some other chemical reaction which subsequently raises the temperature of the medium to the combustion point (Cross and Farrer, 1982). 

For the refiner trying to mitigate the problem of spontaneous combustion, probably the two most important parameters to control are as follows (1) spent filter cake temperature and (2) oil content. Although the actual temperature marking the onset of second-stage charring will vary from plant to plant depending on type of oil and clay activity, the most important point is that spontaneous combustion should not occur if the spent filter cake temperature can be sufficiently lowered before exposure to the atmosphere. Obviously, water addition is one way to lower temperature and this approach is probably the simplest and most reliable method. 

The first analysis performed on the concentrated DPR streams was for pyrophoricity according to the UN Test Method for Division 4.2 (Spontaneously Combustible Materials). The results of this test came back Non-Pyrophoric. Flashpoint testing (Tag Open Cup ASTM D 1310) also gave unexpected results with a flash point of >100 °C. This places the material into the category of a Non-Combustible Liquid. 

Some Corrosive Smoke agents are pyroforic and may spontaneously combust in contact with air. Corrosive Smoke agents are reachve to most metals and organic materials. If these materials are finely divided, interactions may cause spontaneous ignition. Reactions of most Corrosive Smoke agents with water may be violent to the point of explosive. 

For large amounts of pentane up to about twenty times theoretical, the curve began to be sensibly linear after vaporization was complete, but was below that corresponding to mixtures of pentane and nitrogen, showed a point of inflection at 120° C. and then rose slowly to 10° to 15° C. below the ignition point. The temperature of spontaneous combustion fell as the amount of pentane used increased. The speed of combustion passed through a minimum at six times the theoretical amount of pentane, dimiu-... 

SODIUM SULFHYDRATE (16721-80-5) NaHS Combustible solid (flash point 195°F/90°C, 73°F/23°C, 45% solution). Hydrolyzes in moist air to sodium hydroxide and sodium sulfide gas. Reacts violently with water, steam, acid, alcohols, producing heat, sodium hydrosulfide solution, and hydrogen sulfide frames spontaneously combustible. Reacts with acids, acid flimes, forming hydrogen sulfide. Incompatible with acids, amides, organic anhydrides, isocyanates, alkylene oxides, epichlorohydrin, aldehydes, alcohols, glycols, phenols, cresols, caprolactam solution, oxidizers. Corrodes most metals in the presence of moisture. On small fires, use dry chemical powder (such as Purple-K-Powder), water spray, or COj extinguishers. 

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