R. Meyer J. Köhler A. Homburg Explosives

Detonation
Fig. 13. Gap test
p = 105 e 0.0358d
p in kbar, d in mm.
The result of the gap test is recorded as the minimum pressure at
which the acceptor charge detonates.
F. Trimborn (Explosivstoffe vol. 15, pp. 169–175 (1967) described a
simple method in which water is used as the heat blocking medium;
the method can also be used to classify explosives which are hard to
detonate and are insensitive to blasting caps.
The gap test explosive train is directed from bottom to top. The donor
charge (Hexogen with 5% wax) is placed into a plexiglas tube and
covered with water. The acceptor charge to be tested is introduced into
the water column from above. The distance between the two charges
can be easily varied.
A detonating cord, terminating on a lead plate, serves as evidence for
detonation.
Some results: see Table 9.
86