A drop ball impact method have been applied for determining the sensitivity of oxidizer - red phosphorus contact mixtures. The direct impact of a sample by the ball gave lower 50% explosion height than other methods using indirect impact through a steel cylinder or striker etc. The energy (E50) of 50% explosion probability for the sensitive composition was expressed by the E50 for direct drop ball method and listed in the table.
Bromates, chlorates, or chlorites gave extremely sensitive contact mixtures with red phosphorus. Especially, silver chlorate - red phosphorus mixture showed the most sensitive in this work. The experimental of a series of metal peroxides - red phosphorus mixtures distinguished two distinct groups of different sensitivity. The mixture of sodium or potassium peroxide with red phosphorus was very highly sensitive, the second group included Zn, Ba, Ca, Sr, or Mg peroxide were observed forming less sensitive mixture and the energy (E50) of impact explosion was 0.32-0.88 J. The mixture of perchlorates or iodates with red phosphorus gave comparable sensitivity to the explosives alone, namely, Pb(N3)2, DDNP, PETN, RDX, or HMX etc.
The E50 was compared with the specified quantities of hazardous materials by the Japanese Fire Prevention Law and with the packing group of dangerous goods recommended by the United Nations.
