Waterjetting 37b – How safe is it?

We began looking into the use of water jets to deal with energetic materials (a group that includes, but is not limited to, explosives) at the beginning of the 1980’s. One of the earliest questions dealt with the need to find the jet pressures at which the explosive materials would react to the impact of the water.

We produced a short video of that initial work, and with apologies for the degradation that occurs with time and the transfer of the material through different media, here is what I believe was the second report we made, after we had been told that just showing that jets could remove material without reaction was not sufficient.

Figure 1. Looking for the initiation of explosive.

Mrs. Vicki Snelson did the initial commentary with Dr. Paul Worsey developing the technology that we used to see how the explosive was reacting.

Part of the problem, we discovered, was the the jet could start the explosive burning (deflagration) without causing it to detonate, but that the succeeding flow of water would wash that burning material away from the surface. Looking at the surface afterwards did not, as a result, show any reaction signs, and we could not always fully see the contact area. As a result the design was changed, so that the explosive could be held in a small chamber flooded with inert gas. The driving system was changed, so that only water entered the chamber, and so we could determine, by examining the chemical composition of the gases in the chamber after the test, if any reaction had, in fact taken place. Paul explains the modifications.

Figure 2. The first modifications to the test equipment.