RIOFLEX Bubble energy

Perhaps a better test to assess bulk explosives is the underwater test. In this test, a reasonable amount of explosive is detonated under water and the energy released is measured by integrating all the pressure pulses produced by the submerged gas bubble. The shock energy is measured as the energy content of the first high pressure pulse. The bubble energy includes all subsequent pulses and can be considered as an indication of the remaining energy in the explosion gases after detonation. This test does not reproduce actual field explosive performance. However, it gives a measurable partition between shock and heave energies in a given explosive in a constant environment which can be used for comparison between different explosives. In general, this test overestimates performance of low-pressure explosives such as ANFO as energy losses in the water are proportional to the pressure in the medium. The underwater test of RIOFLEX an ANFO are:

(*) As given by P.A. Persson in his recent book: " Rock Blasting and Explosives Engineering".

(**) Test conducted by UEE Explosives.

The values for ANFO taken from the explosives literature appear unusually high. No indication is given as to what sort of ANFO was tested. However, the proportion between shock and heave remains meaningful. As expected, underwater energies are lower than theoretical energies because of energy losses in the water before the energy arrives at the sensor.

The basic fact remains that for a commercial bulk explosive with a certain percentage of water in its formulation, the comparison with a dry explosive such as ANFO in energy terms does not look impressive. It is certainly possible to formulate bulk explosives with a high energy content but at a prohibitive cost that defeats the purpose of high volume, low cost, mechanized bulk explosives technology. One has to read carefully the specifications provided for any given explosive and filter whatever is purely commercial and marketing information convolved with meaningful technical information.