Abstract:
Delay detonator is an explosive device used in various systems including
sophisticated missiles, weapons and warheads. Delay detonators provide
required delay time before certain effect is produced. Delay detonators are
classified according to means of initiation. Bridge wire or hot wire delay
detonator is a type of delay detonator which is initiated thermally by electric
pulse. Required current is passed through the resistive wire which heats up
and provides requisite energy for pyrotechnic composition to initiate. Delay
time is one of the most important performance parameter of sophisticated
missiles, warheads and weapons. It is critical when accurate delay time is
required for some effect to occur in missile / weapons i.e. to perform some
chemical/ mechanical operation after a certain delay time.
The objective of this work is to design and develop an accurate and
reproducible electrically initiated pyrotechnic delay detonator and to determine
the effect of various parameters (Confinment, Obturation, Venting etc) of delay
body on burning rate of pyrotechnic delay composition in delay detonators.
Nichrome wire has been used as a hot wire bridge to provide desired energy to
initiate the igniting charge. The delay time was measured on a set-up
comprising, inter alia, an oscilloscope. The work includes experimental study of
various ignition, delay composition, secondary charge and design of delay
body as well as detail study of different parameters affecting burning rate of
delay compositions in delay detonators and their remedial actions.
The study reveals that the delay time is greatly affected by confinement,
obturation and venting of delay body. It has been further observed that when
the delay composition is initiated in confined body, the results show that the time is considerably reduced as compared to unconfined and obturated delay
body.
