Through-bulkhead initiator

Jan 1969, pp 2-3 [Through Bulkhead Initiator (TBI) was designed in 1961 for use in rocket motor and gas generator ignition systems and since that time thousands of units have been fired with no reported failures of any kind. The TBI s are available in a variety of configurations. For example, the Standard McCormick Selph Unit, P/N 805845 (manufd by the McCormick Selph,... 

Through-Bulkhead Initiator TBI. Through-bulkhead initiators are used to transmit a detonation shock wave through a solid steel bulkhead and initiate a deflagration on the opposite side without perforating the bulkhead or otherwise destroying the integrity of the hermetic seal formed by the bulkhead... 

The forward bulkhead of the motor case is exposed to stagnant but hot gases, and thus must be lined with an insulative material. The modulus of this insulator is sufficiently low so as to transmit the chamber pressure into the external structural member. Insulators that are brittle tend to crack during the initial pressurization, with possible catastrophic burn-through of the motor case wall. Insulators are composed of an elastomer-modified charring resin (like a copolymer of butadiene-acrylonitrile and phenolic) with various reinforcements and/or low conductivity fillers. The bulkhead insulator is generally premolded in segments and then adhesively (plastic) bonded in place. 

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