The Chemistry of Powder and Explosives - Sciencemadness Dot Org

TESTS OF EXPLOSIVE POWER AND BRISANCE 25
op only to explosives which detonate. Black powder and
other explosives which burn produce but little effect, for the gases
blow out the stemming and escape. The test is largely one of
brisance, but for explosives of substantially equal brisance it
gives some indication of their relative power. An explosive of
great brisance but little power will create an almost spherical
pocket at the bottom of the hole in the block, while one of less
brisance and greater power will enlarge the hole throughout its
FIGURE 13. Lead Block Tests (above), and Trauzl Tests (below). (Courtesy
U. S. Bureau of Mines.)
length and widen its throat at the top of the block. The form of
the hole, then, as shown by sectioning the block, is not without
significance. The Trauzl test does not give reliable indications
with explosives which contain aluminum (such as ammonal) or
wrth others which produce very high temperatures, for the hot
gases erode the metal, and the results are high.
A small Trauzl block is used for testing commercial detonators.
Another test, known as the small lead block test, is entirely a
test of brisance. As the test is conducted at the U. S. Bureau of
Mines/a a ieacj cylinder 38 mm. in diameter and 64 mm. high is
upright upon a rigid steel support; a disc of annealed steel