GB2076945A - Pyrotechnic device - Google Patents

Abstract

In a pyrotechnic device two pyrotechnic compositions 4,8 are separated by a slow burning delay 7 of foam plastics material. The two compositions and the delay are so positioned in a container 1 that on ignition of the first composition 4 the delay 7 burns slowly through to ignite the second composition 8 only after the first composition 4 is thoroughly ignited. <IMAGE>

Description

SPECIFICATION Pyrotechnic device The present invention relates to a pyrotechnic device including a delay.

A pyrotechnic device may include a delay where a second pyrotechnic composition is required to be ignited after a first pyrotechnic composition. One such a device is a smoke puff producing device wherein black smoke producing aromatic hydrocar bon composition is expelled by an expulsion charge.

The delay is required to enable the smoke composition to be burning rapidly on expulsion.

The object of the invention is to provide a pyrotechnic device having a cheap, effective delay.

The pyrotechnic device according to the invention comprises a container, a first pyrotechnic composition in the container, a second pyrotechnic composition in the container, a slow-burning foam plastics material delay separating the two compositions and means for igniting the first pyrotechnic composition and the delay on its side opposite from the second pyrotechnic composition, the arrangement being such that the second pyrotechnic composition is ignited when the delay has burned through.

A convenient delay material is expanded polystyrene. Although the pyrotechnic device is preferably a smoke or flare device, the device of the invention may have other uses.

To help understanding of the invention, a specific embodiment thereof will now be described with reference to the accompanying drawing in which the sole figure is a side view in longitudinal crosssection of a black-smoke-generating device.

The illustrated pyrotechnic device is stored in a container in the form of a ring pull can 1. A polyvinyl chloride liner lines the sides and permanently closed end of the can and is located in the can by a constriction. In the open mouth of the liner 2 a closure disc 3 is provided to retain the contents of the device in position. Afirst pyrotechnic composition 4, for example a black smoke composition containing aromatic hydrocarbon, is provided in the upper part of the container, with an ignition fuse extending from above the closure disc 3, through the composition 4 and two primed cambric discs 6 below the composition 4. Below the discs 6 a block 7 of expanded polystyrene is provided in the lower part of the container as a slow burning delay, and a second pyrotechnic composition in the form of an expulsion charge 8, of black-powder is below the delay.At either end of the container packing blocks 9 of expanded polystyrene are included.

For use of the device, an opening of the can 1, the fuse is ignited and it in turn ignites the black smoke composition 4. The fuse also ignites the block 7 of expanded polystyrene. In the time taken for this to melt and burn slowly through to the expulsion charge 8, the black smoke composition is allowed to become thoroughly ignited. Thus when the expul sion charge is ignited the first composition 4 produces a thick smoke.

Expanded polystyrene used for the delay has the advantage of being cheap, and easily and safely handled.

The invention is not intended to be restricted to the details of the above described smoke generating device. Expanded polystyrene, or other suitably slow burning foam plastics material, may be used in other pyrotechnic devices as a delay.

1. A pyrotechnic device comprising a container, a first pyrotechnic composition in the container, a second pyrotechnic composition in the container, a slow-burning foam plastics material delay separat ing the two compositions and means for igniting the I first pyrotechnic composition and the delay on its side opposite from the second pyrotechnic composi tion, the arrangement being such that the second pyrotechnic composition is ignited when the delay has burned through.

2. A pyrotechnic device as claimed in claim 1 wherein the foam-plastics material delay is in the form of a block of expanded polystyrene.

3. A pyrotechnic device as claimed in claim 1 or or claim 2 wherein the first pyrotechnic composition is a smoke producing and/or flare composition and the second pyrotechnic composition is an expulsion charge for expelling the first pyrotechnic composi tion when the first pyrotechnic composition is ignited.

4. A pyrotechnic device as claimed in claim 3 wherein the first pyrotechnic composition is a black smoke composition containing aromatic hydrocar bon and the second pyrotechnic composition is a black powder expulsion charge.

5. A pyrotechnic device as claimed in any pre ceding claim wherein the container is a cylindrical container having one closed and one openable end; the contents of the container are arranged as follows: a first packing block adjacent the closed end of the container; the second pyrotechnic composition adjacent the first packing block, the foam-plastics material delay adjacent the second pyrotechnic composition, the first pyrotechnic composition adjacent the foam-plastics material delay, and a second packing block adjacent the first pyrotech nic composition; and the ignition means includes a fuse extending through the second packing block and the first pyrotechnic composition to the opposite side of the foam-plastics material delay.

6. A pyrotechnic device as claimed in claim 5 wherein the first packing block and the second packing block are formed of expanded polystyrene.

7. A pyrotechnic device as claimed in claim 5 or 6 wherein the container is a ring pull can having a plastics material liner.

8. A pyrotechnic device substantially as hereinb efore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Pyrotechnic device The present invention relates to a pyrotechnic device including a delay. A pyrotechnic device may include a delay where a second pyrotechnic composition is required to be ignited after a first pyrotechnic composition. One such a device is a smoke puff producing device wherein black smoke producing aromatic hydrocar bon composition is expelled by an expulsion charge. The delay is required to enable the smoke composition to be burning rapidly on expulsion. The object of the invention is to provide a pyrotechnic device having a cheap, effective delay. The pyrotechnic device according to the invention comprises a container, a first pyrotechnic composition in the container, a second pyrotechnic composition in the container, a slow-burning foam plastics material delay separating the two compositions and means for igniting the first pyrotechnic composition and the delay on its side opposite from the second pyrotechnic composition, the arrangement being such that the second pyrotechnic composition is ignited when the delay has burned through. A convenient delay material is expanded polystyrene. Although the pyrotechnic device is preferably a smoke or flare device, the device of the invention may have other uses. To help understanding of the invention, a specific embodiment thereof will now be described with reference to the accompanying drawing in which the sole figure is a side view in longitudinal crosssection of a black-smoke-generating device. The illustrated pyrotechnic device is stored in a container in the form of a ring pull can 1. A polyvinyl chloride liner lines the sides and permanently closed end of the can and is located in the can by a constriction. In the open mouth of the liner 2 a closure disc 3 is provided to retain the contents of the device in position. Afirst pyrotechnic composition 4, for example a black smoke composition containing aromatic hydrocarbon, is provided in the upper part of the container, with an ignition fuse extending from above the closure disc 3, through the composition 4 and two primed cambric discs 6 below the composition 4. Below the discs 6 a block 7 of expanded polystyrene is provided in the lower part of the container as a slow burning delay, and a second pyrotechnic composition in the form of an expulsion charge 8, of black-powder is below the delay.At either end of the container packing blocks 9 of expanded polystyrene are included. For use of the device, an opening of the can 1, the fuse is ignited and it in turn ignites the black smoke composition 4. The fuse also ignites the block 7 of expanded polystyrene. In the time taken for this to melt and burn slowly through to the expulsion charge 8, the black smoke composition is allowed to become thoroughly ignited. Thus when the expul sion charge is ignited the first composition 4 produces a thick smoke. Expanded polystyrene used for the delay has the advantage of being cheap, and easily and safely handled. The invention is not intended to be restricted to the details of the above described smoke generating device. Expanded polystyrene, or other suitably slow burning foam plastics material, may be used in other pyrotechnic devices as a delay. CLAIMS

1. A pyrotechnic device comprising a container, a first pyrotechnic composition in the container, a second pyrotechnic composition in the container, a slow-burning foam plastics material delay separat ing the two compositions and means for igniting the I first pyrotechnic composition and the delay on its side opposite from the second pyrotechnic composi tion, the arrangement being such that the second pyrotechnic composition is ignited when the delay has burned through.

2. A pyrotechnic device as claimed in claim 1 wherein the foam-plastics material delay is in the form of a block of expanded polystyrene.

3. A pyrotechnic device as claimed in claim 1 or or claim 2 wherein the first pyrotechnic composition is a smoke producing and/or flare composition and the second pyrotechnic composition is an expulsion charge for expelling the first pyrotechnic composi tion when the first pyrotechnic composition is ignited.

4. A pyrotechnic device as claimed in claim 3 wherein the first pyrotechnic composition is a black smoke composition containing aromatic hydrocar bon and the second pyrotechnic composition is a black powder expulsion charge.

5. A pyrotechnic device as claimed in any pre ceding claim wherein the container is a cylindrical container having one closed and one openable end; the contents of the container are arranged as follows: a first packing block adjacent the closed end of the container; the second pyrotechnic composition adjacent the first packing block, the foam-plastics material delay adjacent the second pyrotechnic composition, the first pyrotechnic composition adjacent the foam-plastics material delay, and a second packing block adjacent the first pyrotech nic composition; and the ignition means includes a fuse extending through the second packing block and the first pyrotechnic composition to the opposite side of the foam-plastics material delay.

6. A pyrotechnic device as claimed in claim 5 wherein the first packing block and the second packing block are formed of expanded polystyrene.

7. A pyrotechnic device as claimed in claim 5 or 6 wherein the container is a ring pull can having a plastics material liner.

8. A pyrotechnic device substantially as hereinb efore described with reference to the accompanying drawing.