Delay compositions for

Boron is virtually unknown in the fireworks industry, but is a widely-used fuel in igniter and delay compositions for military and aerospace applications. 

Study of Nickel-Zirconium Type Delay Composition for Use in 11- to 14-second Primer - Detonator (Oct 1953)... 

Method No 215. Delay Composition for Defay Elements T6E4 and T5E3- Specification MIL-D-46483B(MU)(1964) states that it consists of Lead Chromate (and/or Barium Chromate) and powdered Manganese, but does not list the percentage of components. Procedures were changed by Engineering Order EO-PA-52713-2 (1968)... 

Method No 303. Delay Composition for the M127 (T73) Ground Signal - K nitrate 60.84,... 

Method No 304. Delay and Fuze Compositions. Delay Composition for Parachute Red Star Distress Signal M131(T66E1) and Fuze Composition for Parachute Aircraft Flare M9A2 consist of K nitrate 71.8, S 10.1, charcoal 15-1 carnauba wax 3.0% [PicArsnGenLabRept 55-HI-80(1955)]... 

Sh. Kinoshita T. Yamazaka, Delay Composition for Electric Detonators , JP95 (1959) CA53,20807 (1959)... 

Theoretical Analysis of Resonance Tube , The Singer Company, Final Report KD 72-82 (1972) 58) F.J. Valenta, The State of the Art of Navy Pyrotechnic Delays , Expls Pyrots (The Franklin Institute Research Laboratories) 5, Nos 11 12 (Nov-Dec 1972). See also Ref 144, pp 185—95. See also Some Factors Affecting Burning Rates and Variability of Tungsten and Manganese Delay Compositions , Ref 144, pp 157—83. See also Mil Spec for Tungsten Delay Compositions , MIL-T-23132A (June 1972) 59) C.F. Parrish et al, Radiation... 

J. C. Dawson. Method and composition for delaying the gellation (gelation) of borated galactomannans. Patent US 5082579, 1992. 

Some delay compositions are difficult to ignite and ordinary fuseheads may not be adequate for this purpose. In such cases special fuseheads are used which commonly contain cerium powder, or some similar additive which burns with the evolution of a large amount of heat. 

In the design of the detonator attention must also be paid to the effects of the liberation of gas which, though small, is still sufficient to require attention. As the speed of the delay composition is affected by pressure, it is necessary that the free space in the detonator should be carefully controlled. Also, the plug which seals the leading wires in place must withstand this pressure for more than the delay period of the detonator. This task is made more difficult by conduction, along the metal walls of the detonator shell, of heat liberated by the fusehead and the delay composition. Plastic plugs in particular are liable to soften and be ejected from the detonator with probable failure of burning of the delay column. 

For "gasless" heat and delay compositions, little external pressure effect is expected. This result, plus the increase in burning rate observed with an increase in loading pressure, can be considered good evidence for the absence of any significant gas-phase involvement in a particular combustion mechanism. 

Delay Composition A general term for a mixture that burns at a seleeted, reproducible rate, providing a time delay between activation and production of the main effect. A fuse containing a core of black powder is an example of a delay. Highly-reproducible delay mixtures are needed for military applications, and much research effort has been put into developing reliable compositions. 

Fordham (Ref 51, p 127) states that a common mixture for US delay elements consists of Ba peroxide 85 Se 15% and that for the manuf of millisecond delay detonators, faster burning compns are required such as Si 30-50 red lead (or lead dioxide) 50-70%. Manuf of delay compns is described on pp 128-29, assembly on p 129 and design on pp 129 30 of Ref 51. Ger delay compositions (Verzo-gerungsverbindungen) and delay elements(Verzo-gerungskorper) are described In Ref 35, pp Ger 33 Ger 34... 

Low-Explosive (LE). An explosive which when used in its normal manner deflagrates or burns rather than detonates that is the rate of advance of the reaction zone into the unreacted material is less than the velocity of sound in the unreacted material. LE s include propellants, certain primer mixtures, BkPdr, blasting explosives (See Ref 44, p B202-L), pyrotechnic compositions and delay compositions. Whether an explosive reacts as a high explosive or a low explosive depends on the manner in which it is initiated and confined. For example, a double base propellant when initiated in the usual manner acts as a LE. However, this material can be made to detonate if it is initiated by an intense shock. Conversely, a HE like TNT, can, under certain conditions be ignited by flame and will burn without detonation (Ref 40a, p 97)... 

D. T. Zebree, 53, 17514 (1959) Claims an improved delay fuse for igniting primary explosive compositions in detonators squibs. The preferred delay mixture consists of 60% Ba02,... 

In Ref 2a is described the following procedure for Determination of Barium Chromate in US Delay Composition T10 ... 

Brooks and Valenta (Ref 62) report on the development of reefing line pyrot delay cutters contg W-Viton delay compns. These cutters are used in mid-air retrieval systems for recovery of remotely piloted vehicles. The developed items operate under 2000g acceleration at from —100° to 160°F with time delays of 2.0 to 27 secs Stability of W-Containing Delay Compositions. 

Mono-, di- and tetra-nitro derivatives of carbazole have been obtained. Among them only tetranitrocarbazole is of practical importance. It was used in Germany under the name of Nitrosan as an insecticide. During World War II it was used under the name of Gelbmehl in combustible compositions for delayed action time fuses. 

Figure 2.15 shows a schematic representation of the construction of a 12.7 mm multipurpose projectile with a pyrotechnic mixture (incendiary) and secondary explosive. Figure 2.16 schematically shows the construction of a hand grenade with a pyrotechnic delay composition. Bombs such as, for example, the MK 80 series, where approx. 45 % of the total mass is the explosive, usually contain pyrotechnic ( nose or tail ) fuses. 

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