R. Meyer J. Köhler A. Homburg Explosives

Hot Storage Tests
178
ucts. Various procedures, applicable at different temperatures, may be
employed for this purpose.
1. Methods in which the escaping nitrous gases can be recognized
visually or by noting the color change of a strip of dyed filter paper. The
former methods include the qualitative tests at 132, 100, 75, and
65.5 °C (270, 212, 167, and 150 °F). These tests include the U.S.
supervision test, the methyl violet test, the Abel test, and the Vieille
test.
2. Methods involving quantitative determination of the gases evolved.
Here we distinguish between tests for the determination of acidic
products (nitrous gases) only, such as the Bergmann-Junk test and
methods which determine all the decomposition products, including
manometric methods and weight loss methods.
3. Methods which give information on the extent of decomposition of
the explosive material (and thus also on its stability), based on the
identity and the amount of the decomposition products of the stabilizer
formed during the storage. These include polarographic, thin-layer
chromatographic and spectrophotometric methods.
4. Methods providing information on the stability of the explosive
based on the heat of decomposition evolved during storage (silvered
vessel test).
5. Methods in which stability can be estimated from the physical
degradation of a nitrocellulose gel (viscometric measurements).
The tests actually employed vary with the kind of explosive tested
(explosives, single-base, double-base or triple-base powders, or solid
propellants) and the temporal and thermal exposure to be expected
(railway transportation or many years’ storage under varying climatic
conditions). In the case of propellants about to be transported by train,
only short-time testing is required. However, to obtain an estimate of
the expected service life is required, the so-called long-time tests must
be performed at 75 °C (167 °F) and below. The duration of such a
storage is up to 24 months, depending on the propellant type. Shorttime
tests – the Bergmann-Junk test, the Dutch test, the methyl violet
test, the Vieille test and, very rarely, the Abel test – are mostly
employed in routine control of propellants of known composition, i.e.,
propellants whose expected service life may be assumed to be known.
In selecting the test to be applied, the composition of the propellant
and the kind and amounts of the resulting decomposition products
must also be considered.
Contrary to the common propellants, which contain nitrates, the
so-called composite propellants cannot be tested in the conventional
manner owing to the relatively high chemical stability of the incorporated
oxidants, e.g., ammonium perchlorate. In such cases the stability