R. Meyer J. Köhler A. Homburg Explosives

87 Detonation
Fig. 14. Gap test according to Trimborn
5. Detonation Velocity
donor charge 10 g Hexogen/wax
Detonationsgeschwindigkeit; vitesse de détonation
The detonation velocity is the rate of propagation of a detonation in an
explosive; if the density of the explosive is at its maximum value, and if
the explosive is charged into columns which are considerably wider
than the critical diameter, the detonation velocity is a characteristic of
each individual explosive and is not influenced by external factors. It
decreases with decreasing density of packing in the column. It is
measured by ionisation probes or fibre optical sensors.
The detonation velocities of confined and unconfined nitroglycerine
and nitroglycol explosives have very different values; these values are
known as upper and lower detonation velocities respectively. The
velocity measured in a steel pipe confinement is not attained in a
borehole. Special seismic explosives (e.g. W Geosit) detonate at the
same high detonation rate as measured in the steel pipe, whether
confined or not.