GB605559A - Improvements in or relating to explosive devices for creating disturbances under thewater - Google Patents

Abstract

605,559. Pyrotechnic devices; signalling by audible signals. JONES, E., LEWIS, I. -O., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. March 12, 1945, No. 6208. [Class 9 (ii)] [Also in Group XXXVIII] Relates to explosive devices for creating a regularly spaced sequence of disturbances under water for signalling or like purposes. According to the invention, a container is provided housing at spaced intervals a number of delay action detonators containing a non-detonating gasevolving charge at one end, this end being open and in communication with a common fuze train in a continuous channel in the container. Furthermore, each detonator housing is covered on the exterior by a water-proof closure allowing the detonator to escape after ignition of the gas-evolving charge. The container is built up of a number of discs 3, each disc having on one side an annular ridge 9 nesting in a corresponding groove 13 of an adjacent disc. There is a gap in the ridge and groove of each disc and the discs are so assembled by a pin 14 of one disc fitting in a socket 15 of the disc below that these gaps are helically arranged in the container. By this arrangement a perforation through the disc from the end of a groove communicates with the beginning of the groove in the next disc below. In the lowermost disc 4, the ridge 2 is omitted and below this disc is a terminal plate 5. An upper terminal plate 1 has a ridge 2 nesting in the groove of the top disc 3. An electric igniter 7 fits into a shouldered channel 12 in the upper terminal plate, the lower part of the channel 12 being.open to the groove 13 below. A bolt 6 holds the assembled discs and plates together. In the discs 3 are spaced channels 8 shouldered at their outer ends to accommodate cardboard closure discs 19 after delav action detonators 16 have been inserted. Each housing channel 8 opens through a feeder passage 17 into the lower part of the appropriate groove 13. Strings of a thermoplastic fuze composition are placed in each groove 13 and each disc 3 is hot pressed to cause the fuze composition to overflowinto the feeder passages 17 and the perforation through each disc. After cooling, the exposed face of the fuze composition is varnished. Thus, when the discs are assembled, a continuous fuze train 10 is formed from which branch trains 18 lead to the detonators. Each detonator contains at the open end an ejecting charge of black powder composition succeeded by a delay element, then a burning charge and lastly a detonating charge. A water-proof coating is applied to the exterior of the discs 19 and to the joints of the apparatus. In an alternative form, the device is built up from arcuate wedges fitted into end plates. A fuze accommodating groove runs the length of each wedge, alternate wedges being perforated at the top and the intervening wedges perforated at the bottom of their respective grooves, so that when assembled a continuous fuze passage is formed. From the grooves feeder passages lead as before to detonator housing channels. The upper terminal plate accommodates an electric igniter arranged coaxially with the groove in one of the wedges. The fuze composition is placed in the grooves and treated as in the first form.