R. Meyer J. Köhler A. Homburg Explosives

Lead Block Test
Lead Block Test
Bleiblockausbauchung; essai au bloc de plomb, coefficient d’utilisation
pratique, c. u. p.
The Trauzl lead block test is a comparative method for the determination
of the W Strength of an explosive. Ten grams of the test sample,
wrapped in tinfoil, are introduced into the central borehole (125 mm
deep, 25 mm in diameter) of a massive soft lead cylinder, 200 mm in
diameter and 200 mm long. A copper blasting cap No. 8 with an
electric primer is introduced into the center of the explosive charge,
and the remaining free space is filled with quartz sand of standard
grain size. After the explosion, the volume of the resulting bulge is
determined by filling it with water. A volume of 61 cm3 , which is the
original volume of the cavity, is deducted from the result thus obtained.
In France the lead block performance value is given by the coefficient
d’utilisation pratique (c. u. p.): if mx is the mass of the tested explosive,
which gives exactly the same excavation as 15 g of picric acid, the
ratio
15
· 100 =% c. u. p.
mx
is the coefficient d’utilisation pratique. Also, 10 g of picric acid can be
applied as a standard comparison explosive. For the relationship with
other testing procedures W Strength.
Another modification of the lead block test is recommended by BAM
(Bundesanstalt für Materialprüfung, Germany). The test sample is
prepared as follows: a special instrument wraps the sample in tinfoil
and molds it into a cylinder of 11 ml capacity (24.5 mm in diameter,
Fig. 17. Lead block test
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