Explain why an empty gasoline drum can be more dangerous than a full one. Why is a drum of carbon disulfide more likely to ignite than a drum containing gasoline?
Ordinarily workers believe that the empty drums are not as dangerous as the drums filled with gasoline. However, the reality is just the reverse and it is the main reason that several such accidents have happened in the past due to the ignorance of the workers. Workers generally know that they must handle gasoline filled drums with caution which is because of higher inflammability of the liquid. Once the drum has been emptied, workers believe there is no more danger in handling the empty drums. This is a major misconception since even the few drops of the highly inflammable liquid that might remain in the drum could be sufficient to cause a dangerous explosion. In past, accidents have happened when workers have tried to cut open empty drums using saws. What happens is that the few drops of gasoline that remain inside the drum fill it with dangerous vapors that ignite at the slightest touch of heat. A single spark in such conditions is enough to cause a dangerous explosion that can result in third degree burns. So, even smoking a cigarette near an empty drum that can be filled with explosive vapors may cost someone his life.
The burnability range of gasoline lies between 1.4 and 7.6%. Concentration of gasoline vapors above 7.6% is too rich and below 1.4% is too lean to burn. The full or partially full drums do not have either enough oxygen or sufficient heat to make them explode. Apart from fuel, these two conditions must also be met to cause an explosion. However, workers are generally cautious when dealing with the filled drums. Small sparks fail to cause an explosion or combustion because full or partially filled drums are more likely to have a vapor concentration that is higher than the upper limit of the burnability range. In case of empty barrels the vapor concentration is leaner and lies between the upper and lower limits of the burnability range. Since the vapor concentration is in the burnability range and the drum is filled with vapor a small spark is capable of causing combustion and explosion. Burnability range is the factor that makes a filled drum less and an empty drum more dangerous. It is also the case with carbon di sulphide which gets to be ignited more easily because of its large burnability range.
Gasoline – 1.4% – 7.6%
Carbon Di Sulfide – 1.3% – 50%.
So, the burnability range of Carbon Di Sulfide creates a larger scope for explosion. A drum filled with carbon di sulphide is likely to have vapors within the burnability range and chances of explosion are therefore high. Employers must exercise precautions to protect their workers from the dangers of handling filled or empty drums. Two things can be done to protect the workers. First is to provide adequate training. The second is to label the drums adequately. Sometimes the empty drums can fall into the hands of untrained workers or non-workers. So, if they are labelled adequately and warnings are provided on the label, the danger of explosion will be reduced substantially.
Industrial Safety and Health Management, C. Ray Asfahl, David W. Rieske, Pearson Education