According to the international standard, main problems lying in the process of hazardous zone classification were emphatically analyzed. The source of release was determined in light of its release frequency and duration, namely the continuous source, primary source and secondary source. Considering the effect of release rate, LEL, density, ventilation, obstacles, and meteorological conditions on the classification of the hazardous area, it could be found that the hazardous zone would expand as the release rate increased with lower explosion limit. The gas that was heavier than air covered larger hazardous areas than the lighter gas. Besides, ventilation might speed up the diffusion so as to reduce the scope the hazardous zone; obstacles prevented the diffusion so that concentration of partial gas increased and then the danger level increased; wind at high speed quickened the diffusion to decrease the range of dangerous area. Finally, explosion-proof electrical equipment was selected rationally according to the type of explosive gas and temperature group.
Automatic Detection of Flood Using Remote Sensing Images
