Pyrotechnic time delay element

Abstract

A pyrotechnic time delay element which includes a casing made from a plastics material, a pyrotechnic composition inside the volume, a membrane inside the volume against one end of the pyrotechnic composition and a primary explosive inside the volume on an opposing side of the membrane.

1 - 11 . (canceled) 
     
     
         12 . A pyrotechnic time delay element which includes a casing which is injection-moulded from a non-metallic material, the casing comprising a housing inside which is formed a volume, at least one opening to the volume, a pyrotechnic composition which is loaded into the volume through the opening, and a membrane, inside the volume, which separates an ignition end of the casing from the composition, wherein the membrane has a perforation or opening with a shape, in cross-section, selected circular, square, rectangular, cross-shaped, star-shaped, polygonal, said membrane and cross sectional shape of perforation being used to shape a wave-front, propagated by the pyrotechnic composition, to ensure that optimum ignition of a primary explosive takes place after the time delay element has executed its timing interval. 
     
     
         13 . A time delay element according to  claim 12  wherein the pyrotechnic composition is consolidated inside the volume after it has been loaded into the volume. 
     
     
         14 . A time delay element according to  claim 12  wherein the non-metallic material is a plastics material selected from the following:
 i. thermosetting material; 
 ii. thermoplastics material; 
 iii. material which is reinforced by the inclusion of fibers or by means of radiation; 
 iv. mixture of injection-mouldable materials. 
 
     
     
         15 . A time delay element according to  claim 12  wherein the housing has an external cross-sectional shape selected from the following: circular and polygonal; and, in a longitudinal direction, has a shape selected from the following:
 cylindrical; tapered; and cylindrical with step formations. 
 
     
     
         16 . A time delay element according to  claim 12  wherein opposed ends of the housing are sealed by means of respective closures to protect the pyrotechnic composition which is inside the volume. 
     
     
         17 . A time delay element according to  claim 12  wherein the casing has a wall, around the volume, of constant thickness. 
     
     
         18 . A time delay element according to  claim 12  wherein the casing has a wall, around the volume, of varying thickness. 
     
     
         19 . A time delay element according to  claim 12  wherein the perforation or opening in the membrane, in a longitudinal direction of the casing, varies in cross-sectional area. 
     
     
         20 . A time delay element according to  claim 12  wherein the volume, in a longitudinal direction, has a shape selected from the following: cylindrical, tapered, cylindrical with step formations, and a non-varying cross-sectional shape.