Although its not an accident, this video shows the power of fireworks. Here a Chinese Company is testing a mass ignition of aerial salutes to determine if they detonate or explode one at a time. The result of the test shows a spectacular display of power, but they don’t mass detonate.
May 2000 – Enschede, Holland
The worst fireworks accident in modern history took place in Enschede, Holland at a fireworks warehouse. In May of 2000, a small fire led to two massive explosions, leaving 23 people dead, including 4 firemen. 947 people were injured and an estimated 2,000 homes were damaged or destroyed, leaving over 1250 people homeless.
Fireworks Test Explosions
Below are two more examples of Fireworks test explosions. These were conducted by the European authorities after the Enschede accident. The question is, why do fireworks sometimes mass detonate and sometimes burn (with a lot of popping and banging, but no explosions)?
The two videos below can help explain the answer.
The first video shows a 20 foot metal shipping container that is partially filled with “waterfall tubes”. The Waterfall effect is made with Potassium Perchlorate and Al metal flakes. This combination actually represents the worst case mixture for fireworks as this mixture has the most total energy production.
This is a little counter intuitive, because the waterfall effect seems very tame as fireworks effects go. Its just a soft cascade of bright sparks, as opposed to a loud bang of a firecracker or big burst of an aerial shell. So, why do the waterfall tubes explode in video #2 and just burn in video #1.
The answer has to do with confinement and critical pressures and temperature. Under normal conditions a waterfall tube burns only on the surface of the flame front, consuming a little bit of the energetic mix at a time.
In the first video with a partially filled container, we see just this. We see the waterfall sticks burning for over 1 minute. The fire is fierce and certainly even the metal shipping container is badly damaged from the intense heat, however once the fuel is burned up, the event is over.
In video #2, the container is completely full with 8,661 KG or 19,000 pounds of waterfall tubes!!
This is a huge amount of waterfall tubes and likely no one would ever ship 19,000 pounds of only waterfall tubes. Therefore, the test is a little unrealistic. Also, the metal shipping container is locked closed and the test is initiated by detonating a explosive cap. This in itself is unrealistic because it is a small explosion in itself that would not represent typical initiation sources such as a tiny spark or some other natural event. The point is that the explosive cap got things off to a much faster start inside the container.
In Video #2 we see that the temperature and pressure builds inside the container very quickly, and instead of the waterfall tubes burning a little at a time, 100% of the composition heats up and vaporizes at once. This releases a tremendous amount of energy at once time and the result is an explosion.
The videos prove that given enough explosive powder (19,000 pounds), enough confinement (a sealed metal shipping container) and a good start (an explosive cap). Even fireworks can reach a critical tipping point and be violently consumed in a fraction of a second.
The moral of the story, fireworks can be safely shipped in metal shipping containers as long as the critical mass of explosive content is not exceeded and enough filler material (paper tubes, paper packing cartons, etc.) are included to dampen the spread of the fire.