Flammable mixtures Pressure effects

Liquids present a different case. Some liquids will give off dangerous quantities of flammable vapors well below normal room temperature (the vapor pressure of a liquid is a measure of this effect) others do so at points only slightly above room temperature, and still others at much higher temperatures. It is apparent that the temperature at which a liquid evolves vapors which can form flammable mixtures with air is a measure of its hazard potential. This is indicated by the flash point... 

Diameter of particles of combustibles (mm) Fig. 3. 63 Effect of granule size of flammable materials on deflagration of oxidizer/flammable mixtures in the improved lime/ pressure test Sample quantity 5g... 

Below atmospheric pressure there is no effect on the limits of flammability of natural gas-air mixtures and most other gas-air mixtures. Below about 25 mm absolute pressure, carbon monoxide-air mixtures are not flammable. 

FIGURE 3-9. Effect of various gases on the flammability limits of methane-inert-gas-air mixtures at 25°C (77°F) and atmospheric pressure (Zabetakis 1965). 

Figure 7-50. Effects of pressure on limits of flammability of ethane-nitrogen-air mixture at 26°C. By permission, U.S. Bureau of Mines, Bulletin 627 [43],...

Mixtures of the tetraoxide with dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, trichloroethylene and tetrachloroethylene are explosive when subjected to shock of 25 g TNT equivalent or less [1], Mixtures with trichloroethylene react violently on heating to 150°C [2], Partially fluorinated chloroalkanes were more stable to shock. Theoretical aspects are discussed in the later reference [2,3], The effect of pressure on flammability limits has been studied [4],... 

Figure 4.17 shows the effect of elevated pressure on the flammability of natural gas in mixtures with nitrogen and air. We see the upper limit significantly increase with... 

Figure 4.17 Effect of pressure on limits of flammability of natural gas-nitrogen-air mixtures at 26 °C (taken from Zabetakis [5])...

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