Stab detonators

MECHANICAL initiators PERCUSSION PRIMERS, STAB DETONATORS, AND FRICTION PRIMERS... 

In instances where the expl is to be detonated without a primer and whose output will not reliably initiate secondary HE charges, the initiator takes the form of a stab detonator (Refs 8,12 13), a diagram of which is shown in Fig 4... 

As shown in Fig 4, the stab detonator is a small, sensitive component which is capable of reliably initiating high-order detonation in the next HE element in the expl train. It differs from the primer in that its output will initiate reliably secondary HE charges... 

Stab detonators are made in the form of cylindrical cups of Al, stainless steel, Cu, or gilding metal.. The open end is sealed with a closing disc of metal or of paper over which the end of the cup is crimped... 

Since stab detonators contain no restraining anvil as do percussion primers, the resistance to penetration of the firing pin becomes quite im-. portant. This is the role of compression or density of the mixt. With higher density, the kinetic energy of the firing pin is dissipated over... 

Pb Azide (LA), which is the most important expl used in detonators (Ref 11), although extremely sensitive to shock, heat, and friction, is not sufficiently sensitive to stab action to insure 100% reliability in firing from the stab action. Consequently, the priming mixt is used as a first-fire layer in these units. RDX (cyclotri-methylenetrinitramine), also known as Cyclo-nite, is contained as the output charge of the typical stab detonator. Its output results in a detonation of other expls (Ref 11)... 

The selection of a stab detonator for a specific application requires a consideration of both input and output (Ref 7). The situation exactly duplicates the problems encountered in the selection of a percussion primer. However, as previously discussed, the end purpose of a detonator is different the input energies are significantly lower, and the output is intended to initiate a high expl. In addition to the main criteria, consideration must also be given to size, weight, cost, and reliability... 

When designing a stab detonator, the engineer will select the firing pin so that the entire initiation mechanism is under control. This permits close coordination with other systems designers involved in the weapon development, and thus insures that the stab detonator will receive the proper stimulus... 

The output of a stab detonator is a detonation. Unfortunately, available output data are more nonspecific than input data so that firm, quant choices of output are difficult to make. Consequently, comprehensive testing is usually required (Refs 6 12)... 

In addition to the type of output, the functioning time of the detonator, which is the interval from delivery of the input to the stab detonator until the output of the initiator is realised, is of considerable importance. Where fast initiation is required, the use of LA is essential and, in addition to being used as the intermediate charge, is sometimes incorporated in the initial priming charge in minor percentages to decrease the operation time of the LSt mixt... 

Both the Pb disc test and the steel dent test are of particular significance to stab detonators. As a matter of illustration, the steel dent test (Ref 10) consists of firing a detonator in direct end-on contact with a steel block. The depth of the dent produced is a measure of output. The depth, or better, the volume of the dent correlates well with initiation effectiveness. The low-rate detonation, which crushes nearly as much sand as high-order detonation, makes no dent in a steel plate. It has been demonstrated that the depth of the dent is proportionate to the excess of pressure over the yield strength of the steel of the dent block, integrated over the volume of the detonation head. It has been found that a detonator of 0.190-inch diameter or larger, which produces a dent 0.010 of an inch deep in a mild steel block, will initiate a lead of Tetryl or RDX under favorable conditions. Specification requirements for detonators to be used in fuses are usually at least 0.015 to 0.020 inch in depth, and many produce dents up to 0.060 inch deep... 

The base charge of stab detonators had usually been Tetryl but present designs use RDX... 

A list of some of the more commonly used stab detonators, together with a short compilation of some important factors for each, is shown in Table 6... 

Detonators are used to detonate high explosives. Stab detonators are initiated by sharp firing pins and are used in explosive trains of different types of fuses. Flash detonators are initiated by flames produced by safety fuses, primers, or delay elements. A special type of flash detonator ignited by the flame of a safety fuse is called a blasting cap. Detonators are primarily composed of three types of explosives including sinoxid mixtures, lead azide-based mixtures, and mercury fulminate-based mixtures. 

In this work, we initially performed a thorough study of the challenges to synthesize DBX-1 when using these raw NaNT solutions, including an investigation of the specific impurities, which ultimately prevent formation of DBX-1. A safer and simplified procedure for the preparation of NaNT was thus developed and detailed herein. It is demonstrated that the produced material from the new procedure is of sufficient purity to be used for the preparation of DBX-1. The DBX-1 prepared from this NaNT functions comparably to current state-of-the-art DBX-1 in stab detonators and is of comparable sensitivity. 

Performance tests consisted of loading DBX-1 as a transfer charge in U.S. Army M55 stab detonators. Standard M55 detonators consist of three separate explosive layers, pressed sequentially into a metal detonator cup as shown in Figure 6. The first layer is 15 mg of the stab initiation mix (NOL-130) it is a combination of lead azide, lead styphnate, barium nitrate, antimony sulfide, and tetrazene [l-(5-tetrazolyl)-3-guanyltetra-zene hydrate], pressed at 70,000 psi. The second layer is 51 mg of transfer charge, lead azide, pressed at 10,000 psi. Lastly, the third layer is 19 mg of output charge, RDX, pressed at 15,000 psi. 

This starts the action of other elements of explosive train which consists of a Tetryl "lead", a relay detonator, and a booster charge. The stab detonator consists of a cup, which is made of A1 or A1 base alloys if LA is one of the expl ingredients, whereas Cu or Cu base alloys are used for detonators contg MF. The cup might have any one of several designs of its sensitive end closures, such as two disk-closed ends one disk-closed end one coined end one coined end one open end and one disk-closed end one open end... 

The length of US Military stab detonators varies from 0.250 to 0.750 inch and the external diam from 0.110 to 0.300 inch the wall thickness of cups from 0.005 to 0.025 inch, while the thickness of sensitive end varies from 0.001 to 0.005 inch... 

Fig 21 for stab detonators M18, M24 M44 and for flash detonator M17 are used. In these cuts, the lower(base) charge can be Tetryl, RDX or PETN, the intermediate charge is LA and the upper (top) charge is a priming composition... 

Determination of the Feasibility of Initiating PB-RDX Pellets Using the M46 Stab Detonator " (Sept 1963)... 

Method No 207a. US Military Spec MIL-D-45441C (MU) (1966) covers the requirements of Stab Detonator M61, while MIL-D-462098B (MU) (1968) covers the requirements of Detonator M44E1. Composition of primer mixture for each of these detonators is the same as listed in Method No 207, except that Basic LSt can be replaced by Normal LSt. Following are the procedures ... 

Figure 7 Test Set Mk 136 Mod 0 for Stab Primers and Stab Detonators...

The shape of the firing pin commonly used in (he US is constructed as shown in Fig F3 (Ref 1). Common firing pin materials include both. steel and aluminum alloys. Rear end of pin may be shaped in any way convenient for assembly. Alignment of pin with respect to primer and surface finish of pin ate important and affect the sensitivity (Ref 2). Fig F4 shows a typical stab detonator. For more information on stab detonators, see Vol 4, pp D844-L to D846-L... 

Mixture No 92 - NLSt 40.-2 Sb sulfide (Grade I, class a) 60.-2% (p VIIG). This mixt has been used as a primer chge (20 mg) in Stab Detonators T92 T93 with LA (90 mg) as an intermediate chge and RDX (34 mg) as a base chge (p VIIE)... 

Stab Initiation. See under Stab Detonators in Vol 8, P381-R toP385 Instantaneous Stab Fuze Detonators in Vol 4, D844-L to D846-L and Instantaneous Stab Fuze Primers in Vol 4, D850-L to D852-L... 

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