Small scale gap test

Effect of Interstitial Gas Pressure on the Small-Scale Gap-Test... 

Fig 11 Small Scale Gap Test (SSGT) Data for PETN (Ref 100a)... 

Fig 12 Effect of Interstitial Gas Pressure on the Small-Scale Gap-Test Sensitivity of High Specific Surface PETN (Ref 96)... 

Liddiard Jr, "The Small Scale Gap Test Calibration and Comparison with the Latge Scale Gap Test , NOLTR 66-87 (1966) 15) R.W. 

C) Small Scale Gap Test used at LASL is a modified version of test described by Cachia Whitbread (Ref 37b). It uses unconfined samples, 0.5-inch diam 1.5-in long. A similar test is described by Donna Price (Ref 80) (See also Ref 47a)... 

M.C. Chick, "The Effect of Interstitial Gas on the Shock Sensitivity of Low Density Explosive Compacts , 4th ONRSympDeton (1965), pp 349-58 [A small scale gap test, briefly described on pp 350-51, has been used to investigate the role played by interstitial gases in the shock initiation of granular cylindrical charges of HMX (p = 1.14g/cc with 40% voids) and PET tf (p =... 

Donna Price T.P. Liddiard, Jr, "The Small Scale Gap Test Calibration and Comparison with the Large Scale Gap Test", NOLTR 66-87(1966), White Oak, Maryland [The SSGT, first described in 1952 by Dim-mock, Jr (Ref 26), has been used in its modified form, described in 1961 by Ayres (Ref... 

Shock-Pass-Heat-Filter (SPHF) Sensitiviry Test (Vbl 4, p D316 with Fig 1 and p DJ99-1) Small Scale Gap Test (SSGT) (Vol 4, p D343-R D344 with Fig 35)... 

The most significant parameter involved in daton transfer appeared to be the amt of energy induced in the acceptor expl by the donor. Small Scale Gap Test (See Vol 4 of Encycl, p D1085-R) results provided an indication of the amt of energy reqd to initiate an acceptor expl (Ref 1)... 

Price and Liddiard, in their extensive study (Ref 17) of shock initiation in the gap test (see Vol 6, G13-R) give the following input shock press amplitudes for 50% thresholds (Vi the tests were detons and Vi the tests were failures) for RDX in their SSGT (small scale gap test) set-up (5.1mm ID test expl columns, 38,1mm long, confined in 25.4mm OD brass... 

Small Scale Gap Tests. See under Influence Tests in Vol 7,I98-R to I100-R Addnl Ref Anon, EngrgDesHndbk, Explosives Series—Explosive Trains , AMCP 706-179 (1974), pp 3-4 to 3-11... 

Fig. 3.86 Display of the sensitivity of the small scale gap test and the variable ignitor test(e.g.PETN DNB) 5 4 ...

Fig. 3.117 Test results of small scale gap test of Dynamites and black carlit...

Dinegar, Rochester, Horton and Johnson [145) examined the shock sensitivity of PETN and came to the conclusion that the nature of the gas in a small scale gap-test influences the sensitivity of PETN. Thus He, Ar. Nj and COj have a desensitizing effect, whereas oxygen sensitized the compressed charges. 

The detonation velocity refers to the velocity of the shock front relative to the unreacted material. Peak shock pressure needed to initiate RDX and other secondary explosives as a function of density and particle size have been measured by the small scale gap test [48]. For RDX, which is commonly used in detonators, peak pressure for initiation is found to range from 9 to 16 kbar. Since even under nonideal conditions lead azide produces over 100 kbar, as shown in Table VI, if enough azide is present, it readily initiates RDX, and other secondary explosives, as shown in Table VII. 

Donor-acceptor tests, employing gaps between the donor and the acceptor, have been used to measure the shock sensitivities of explosives. The small-scale gap test is a refined version which employs a steel dent block and Lucite in the gap [1]. The gap decibang (dbg), analogous to the decibel, but relative to a reference level, is used as a measure of the stimulus ... 

Figure 29. Small-scale gap-test data for dextrinated lead azide [48],...

The results are in reasonable agreement with some small-scale gap tests, which gave threshold initiation levels of 4-6 kbar for lead azide [50] they are also consistent with an experiment performed by Roth [28], who observed an initiation in 95% lead azide-5% Teflon (p = 2.7 g/ml) subjected to an 8.5-10-kbar shock. 

A miniaturized version of the gap test, also developed at NOL and called SSGT (small scale gap test) is shown in Fig 4. Note the heavily confined donor and acceptor... 

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