Patent ID: 7434515

Claim:
A signal transmission fuse comprising: an elongated tube assembly having a cylindrical outer surface of perimeter P o , and a non-cylindrical inner surface, said inner and outer surfaces being of radial constant cross section along the longitudinal length of said tube assembly, a reactive powder adhering to said non-circular inner surface at a powder surface density in the range of 1.4 to 7 grams per square meter, said elongated non-cylindrical inner surface having a non-circular cross section of closed contour of peripheral extent (P i ) such that the ratio P i /P 0 lies in the range of 0.4 to 0.5, said outer and inner peripheries defining a variable wall thickness around the tube assembly axis such that said inner periphery is defined by radially inwardly extending ribs and adjacent outwardly expanded flutes that provide a minimal wall thickness in the range of 0.8-0.7 mm, whereby said inner periphery (P i ) is 25% 40% greater than that provided with a cylindrical bore of said minimum wall thickness, said elongated outer cylindrical surface having a circular cross section of a diameter less than 2.5 mm.