تسجيل الدخول

تسجيل

EXPLOSIONS AND EXPLOSIVES

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  479

2026-08-22

29

EXPLOSIONS AND EXPLOSIVES

If a fuel such as gasoline is confined to a closed space, such as a cylinder in an automobile engine, the fuel and oxygen are compressed, raising their temperature. The spark from the spark plug causes a very rapid combustion to take place. This is called a conflagration. The difference between an explosion and a fire in this case is the speed of the reaction. Explosions can also be made to occur without confining the fuel. For example, if the fuel and the oxygen are physically mixed and the oxygen is combined with another element instead of itself, it can be made to explode. An example of this is ANFO—ammonium nitrate (NH₄NO₃) and fuel oil. Pellets of ammonium nitrate are coated with fuel oil. The ammonium nitrate supplies the oxygen that is easily released and very close to the fuel. The resultant combustion is very rapid and is an explosion. ANFO is classified as a low explosive because the velocity of the explosion is not as powerful as in the case of more energetic explosives. It is also possible to combine the oxygen and fuel into a single molecule. In this case, the oxygen and fuel are chemically combined. This is the most advantageous situation for combustion to take place. Such materials undergo instantaneous combustion or detonation. Of course, the combustion is not really instantaneous, there is always a time lag, but it is even more rapid than in a conflagration. The speed of a detonation is referred to as the detonation velocity and these can range from 9000 fps to over 25,000 fps, which works out to be almost 5 miles in 1 s. These are high explosives. Examples include trinitrotoluene (TNT) and nitroglycerine (NG).