Angle shot mortar

Fig. 137. Diagram of angle-shot mortar test at Dortmund-Deme, according to...

The latter may be 90° or less, as is shown in Fig. 137. The reflection of the detonation products from a barrier such as the ricochet plate involves a violent rise in temperature at this spot, due to the adiabatic compression of gases. A general view of angle shot mortar at Derne is given on Fig. 138. 

In Poland another system is also known that works on the same principle as the angle-shot mortar. This is a mortar with a horizontal slit. Figure 139 shows diagram-matically the arrangement in a rectangular section gallery at Mikoldw. 

Fig. 138. General view of angle-shot mortar at Dortmund-Derne [45],...

The classical method of firing explosives in a testing gallery with the charge inside the mortar does not present a true picture of the safety of explosives towards coal-dust since the explosives commonly used fail to ignite coal-dust under such conditions. The angle shot mortar (Fig. 138) is therefore sometimes used as an unofficial auxiliary test. 

Class II safety explosives must fulfil new conditions when tested in an angle-shot mortar 350 g of explosive fired in this mortar at a distance of 65 cm from the wall and at an angle of 40° must not ignite a 9% methane-air mixture. The charge is increased by increments of 25 g. The charge limit should not give an ignition in any of five consecutive shots. 

Class III safety explosives must be safe in a 9% methane-air mixture when fired with the maximum number of cartridges that can be placed in a row in the 2 m long groove of the angle-shot mortar. The experiment starts with 1800 g charge. It is increased by 200 g increments. The charge limit is determined this should not give any inflammation in five consecutive shots. 

ANFO = ammonium nitrate fuel oil 16 20 167 199 angle shot mortar test 269 Anilite = mixture of N204 and butane (french)... 

Kampfer = camphor 49 Kanaleffekt = channel effect 58 Kantenmorser = angle shot mortar 251... 

A specially dangerous condition can arise when several shots are fired in one round by means of electric delay detonators. A preceding shot may then break the coal of another hole or even cut off the whole burden of the charge in question so that it is partly or completely exposed. This condition is simulated in the angle-mortar test. 

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