Meyer R., Koehler J., Homburg A. Explosives. Wiley-VCH, 2002 / Explosives 5th ed by Koehler, Meyer, and Homburg (2002)

Trixogen

A pourable mixture of RDX with TNT.

Trunkline

W Detonating Cord

Ullage*)

Empty volume provided for thermal expansion of propellant in liquid propellant tank.

Unbarricaded*)

The absence of a natural or artifical barricade around explosive storage areas or facilities.

Unconfined Detonation Velocity*)

Detonationsgeschwindigkeit ohne Einschluss; velocite de detonation sans enserrernent

The detonation velocity of an explosive material without confinement; for example, a charge fired in the open.

Underwater Detonations**)

Unterwasserdetonationen; detonations´ sous l’eau

Destructive effects of underwater detonations, differ in their distant and proximity effects. The first effect is caused by the action of the pressure shock wave, the latter mainly by the thrust produced by the expanding gas bubble.

Basically the process can be subdivided into three distinct stages:

1. Detonation

The detonation of an explosive charge is triggered off by the fuse. The explosive matter undergoes an extremely rapid deterioration, and the

* Text quoted from glossary.

**Extract of a lecture held by W. E. Nolle at the annual meeting of the Fraunhofer Institut at Karlsruhe, 1978.

Trixogen

A pourable mixture of RDX with TNT.

Trunkline

W Detonating Cord

Ullage*)

Empty volume provided for thermal expansion of propellant in liquid propellant tank.

Unbarricaded*)

The absence of a natural or artifical barricade around explosive storage areas or facilities.

Unconfined Detonation Velocity*)

Detonationsgeschwindigkeit ohne Einschluss; velocite de detonation sans enserrernent

The detonation velocity of an explosive material without confinement; for example, a charge fired in the open.

Underwater Detonations**)

Unterwasserdetonationen; detonations´ sous l’eau

Destructive effects of underwater detonations, differ in their distant and proximity effects. The first effect is caused by the action of the pressure shock wave, the latter mainly by the thrust produced by the expanding gas bubble.

Basically the process can be subdivided into three distinct stages:

1. Detonation

The detonation of an explosive charge is triggered off by the fuse. The explosive matter undergoes an extremely rapid deterioration, and the

* Text quoted from glossary.

**Extract of a lecture held by W. E. Nolle at the annual meeting of the Fraunhofer Institut at Karlsruhe, 1978.

heat developed during this process creates a large amount of gas. This first enters into the cavity previously occupied by the solid explosive and is therefore under a high degree of pressure. This hot compressed gas constitutes the whole of the performance potential.

2. Shock wave

The adjacent layer of water is compressed under the influence of this high pressure, which in turn transfers that pressure onto the next layer, and this transfers the pressure onto the next one, and so forth in a chain reaction.

The velocity of propagation increases with pressure, thus creating a steeply ascending pressure front, which imparts the nature of a shock wave to the pressure wave. At the onset, the velocity of propagation exceeds that of the speed of sound, but deteriorates with increasing distance, i.e. to approximately 1450 m/s.

The maximum pressure achieved is directly proportional to the cube root of the charge weight, and inversely proportional to the distance, resulting in the following approximate formula:

L1/3

Pmax = C e

p: pressure in bar

L: loading weight in kg e: distance in m

c: empirical factor; ≈ 500

3. Gas bubble

As stated previously, the gas formed by the underwater explosion first enters the small cavity previously occupied by the explosive, thus creating a gas bubble under a high degree of pressure. The water surrounding the bubble gives away, and the gas bubble expands. This causes the water mass to move radially at great velocity away from the point of explosion. This movement is known as the “thrust”.

The maximum amount of kinetic energy imparted to the water during an explosion is called the thrust energy.

The increase of expansion of the gas bubble causes a decrease in pressure on the enclosed gases, which slows down expansion to the point where all of the kinetic energy is expended. This causes lowering of pressure in the gas bubble contents, influenced by the static water pressure, and the water mass engulfs it again. The gases are compressed again up to a second minimum, at which point another pressure wave is formed (secondary pressure wave). Oscillation of the gas bubble can be repeated several times, causing a third, and, under favorable conditions, further minima. The gas bubble is propelled

upwards towards the surface of the water. The difference in pressure between the top and the bottom layer of the bubble causes the bottom layer to move at greater speed, thus forcing it upwards into the bubble. It is possible for both surfaces to meet. Within a limited area the water receives an upward thrust, creating the so-called waterhammer (water jet).

From the observations it becomes clear that the most effective underwater explosives are those which can produce a high-pressure gas bubble for the formation of the thrust.

Mixtures containing a high percentage of aluminum powder have proved to be most effective (W Aluminum Powder; W Torpex; W Trialenes; W Tritonal).

References:

G. Bjarnholt and P. Holmberg, Explosive Expansion Work in Underwater Detonations, Reprints of the Sixth Symposium on Detonation, San Diego, 1976 (from: Office of Naval Research, San Diego, USA).

S. Paterson and A. H. Begg, Underwater Explosion, Propellants and Explosives 3,63–89 (1978).

Upsetting Tests

Stauchung; ecrasement´ du crusher

Upsetting tests are used to determinate the W Brisance of the explosives. An unconfined cartridge (envelopped in paper or in metal sheet) acts upon a copper or lead crusher; the loss of height of the crusher is a measure for the brisant performance of the tested explosive (W Brisance).

The test according to Kast is shown in Fig. 25; the cartridge shock acts by means of a guided pestle onto a copper crusher of 7 mm P and 10.5 mm height.

The simplified test according to Hess is shown in Fig. 26 (see opposite page):

A lead cylinder, 60 mm (2.36 in.) high, 40 mm (1.57 in.) , protected by two, 6 mm-thick steel disks, is upset by a 100-g (3.53 oz.) cartridge of the same diameter, 40 mm. The cylinder is pressed down into a mushroom shape; in the case of sensitized special gelatins for seismic use, the cylinder can be destroyed completely.

electrostatic discharges is required. They are safe against 0.45 A and 8 mJ/ohm. All-fire current is 1.5 A, all-fire energy 16 mJ/ohm. U-detonators are available as instantaneous detonators and with 20 ms and 30 ms short period delay, 18 delays each, and 24 delays of 250 ms long period delay.

U-Zündmaschinen: the corresponding blasting machines are produced by WASAGCHEMIE Sythen, Germany or Schaffler & Co., Wien, Austria.

Vacuum Test

This test, which was developed in the USA and has been adopted by several countries, and is a modification of the W Taliani Test, in which the gaseous products of the reaction are determined volumetrically rather than by manometry. The test, which is carried out at 100 °C (212 °F) for single base propellants and at 90 °C (194 °F) for multibase propellants, is terminated after 40 hours, unlike the Taliani Test, which is interrupted after a given pressure or a given volume has been attained.

The vacuum test is used for compatibility testing and applied as a so-called reactivity test. The compatibility between the explosive and the contact material (adhesive, varnish, etc.) is tested by determining the gases liberated by the explosive alone, by the contact material alone, and by the two together. The measure of compatibility (reactivity) is the difference between the sum of the gas volume liberated by each component separately and the gas volume obtained after storing the explosive and the contact material together. If this difference is between 3 and 5 ml, the compatibility is considered „uncertain“; above 5 ml, the two materials are incompatible.

Veltex No. 448

electrostatic discharges is required. They are safe against 0.45 A and 8 mJ/ohm. All-fire current is 1.5 A, all-fire energy 16 mJ/ohm. U-detonators are available as instantaneous detonators and with 20 ms and 30 ms short period delay, 18 delays each, and 24 delays of 250 ms long period delay.

U-Zündmaschinen: the corresponding blasting machines are produced by WASAGCHEMIE Sythen, Germany or Schaffler & Co., Wien, Austria.

Vacuum Test

This test, which was developed in the USA and has been adopted by several countries, and is a modification of the W Taliani Test, in which the gaseous products of the reaction are determined volumetrically rather than by manometry. The test, which is carried out at 100 °C (212 °F) for single base propellants and at 90 °C (194 °F) for multibase propellants, is terminated after 40 hours, unlike the Taliani Test, which is interrupted after a given pressure or a given volume has been attained.

The vacuum test is used for compatibility testing and applied as a so-called reactivity test. The compatibility between the explosive and the contact material (adhesive, varnish, etc.) is tested by determining the gases liberated by the explosive alone, by the contact material alone, and by the two together. The measure of compatibility (reactivity) is the difference between the sum of the gas volume liberated by each component separately and the gas volume obtained after storing the explosive and the contact material together. If this difference is between 3 and 5 ml, the compatibility is considered „uncertain“; above 5 ml, the two materials are incompatible.

Veltex No. 448

Versuchsstrecke

Berggewerkschaftliche Versuchsstrecke

D-44239 Dortmund-Derne

German institute for research and testing of equiptments and materials for use in gassy coal mines (including W Permitted Explosives, W Bridgewire Detonators and W Blasting Machines).

Vibrometer

Erschütterungs-Messgerät

Vibrometers are instruments to measure the intensity of shock waves caused by blasting operations. The magnitude of the shock depends on the kind of rocks, underground conditions and distance to the people and buildings to be protected. The regular control of ground shocks caused by blasting is therefore, in the interest of companies active in this field to safeguard friends relations with the neighborhood. Vibrometer records, can also be important in forensic defense against claims in densely populated areas.

The following vibrometers are developed, produced and distributed by WASAGCHEMIE Sythen, Haltern, Federal Republic of Germany:

Vibrometer ZEB/SM 3 and. ZEBI/SM 6 DIN 45669

Indication of the maximum values in alphanumeric display. Registration of the complete recording with the aid of an UV (ultraviolet) recorder.

Vibrometer ZEB/SM 3 DS and ZEBI/SM 6 DS DIN 45669

Indication of the maximum values and frequencies on the screen. Registration of the complete recording with the aid of a four-color plotter, also in graphics form.

Vibrometer ZEBI/SM 6 C DIN 45669

Latest processor technology with hard and floppy disk storage possibilities. Display on a screen and registration of the complete recording on a four-color plotter, both also in graphics form.

Vieille Test

This method for the stability testing of propellants was proposed by Vieille in 1896. The sample is heated at 110 °C (230 °F) in the presence of a strip of litmus paper, and is then exposed to air at room temperature overnight, after which the cycle is repeated. This treatment is continued until the litmus paper turns red within one hour. The overall duration of the heating operations thus performed is a measure of the stability.