Journal of Hazardous Materials B137 (2006) 1074–1078 Primary explosives: Electrostatic discharge initiation, additive effect and its relation to thermal and explosive characteristics M.B. Talawar, A.P. Agrawal ∗ , M. Anniyappan, D.S. Wani, M.K. Bansode, G.M. Gore High Energy Materials Research Laboratory, Pune 411 021, India Received 16 February 2006; received in revised form 16 March 2006; accepted 21 March 2006 Available online 15 May 2006 Abstract All explosives, under all conditions must be considered vulnerable to generation, accumulation and discharge of static charge. The low energy static hazards of the order as low as 2–3mJ need to be guarded against in case of highly sensitive compounds namely primary explosives. The hazard is normally associated with manufacturing and filling operations due to discharge of static charge accumulated on a person supplying energy up to 20mJ. To reduce the risk associated with static initiation hazard in the processing and handling of the explosives, the electrostatic sensitivity tests can provide an important input regarding electrostatic hazards. This paper presents electrostatic sensitivity data in terms of zero ignition probability data (E SE0 ) of some of the initiatory explosives such as nickel/cobalt hydrazinium nitrate, silver azide, lead azide and mercury salt of 5-nitro tetrazole. Similar data has also been presented for samples coated with polyvinyl pyrrolidone to study its effect on electrostatic sensitivity. The electrostatic spark sensitivity of some conventional and novel made to explain the increased spark sensitivity behavior on the basis of the possible primary explosives has been studied. The electrostatic spark sensitivity of primary explosives decreased in the order of AgN 3 = NHN > PbN 6 > MNT > CoHN > BNCP. A possible correlation of spark energy with approximation and assumption has been drawn with thermal, detonation and mechanical properties. The polyvinyl pyrrolidone coated samples followed the same order but interestingly with increased spark sensitivity. An attempt has been reasoning of dielectric nature of the materials or exothermic effects of decomposition products of PVP. The present work also reports the electrostatic spark sensitivity of cap compositions. © 2006 Elsevier B.V. All rights reserved. Keywords: Primary explosives; Electrostatic spark sensitivity; Additive effect on thermal and explosive characterization 1. Introduction The hazards related to explosives due to static charge/ electricity have been studied since long. All explosives are high nonconductors and electrostatic potentials are developed upon these explosives. This can readily produce spark discharge between them and earthed articles. If such spark discharge takes place in the vicinity of explosive materials, even low energy spark of the order of 2–3 mJ is enough to initiate the primary explosives, which may lead to detonation causing damage to surroundings. The static discharge hazard is normally associ- ated with manufacturing and filling operations accumulated on a person supplying energy up to 20 mJ. In estimating such types of electrostatic hazards associated with explosives, the informa- ∗ Corresponding author. Tel.: +91 20 25869303; fax: +91 20 25869316. E-mail address: anniyappan@yahoo.co.in (M. Anniyappan). tion of minimum spark energy required for initiating the primary explosives is most essential. Recent papers [1–6] published in the field of electrostatic initiation of sensitive energetic mate- rials, bring out that spark sensitivity depends not only on the chemical entity of the material given granulometry and grain shape, mechanical properties, temperature and moisture content but also on the configuration of electrodes and stricture of cir- cuit [7]. There is no standard apparatus available for estimating the deflagration energy levels of such explosives. Therefore, it has not yet been possible to devise an international standards test specifying these hazards. There are several methods used in USA organizations [8]. RARDE in UK [9], Mizushima [10] and Kuroda and Nagaishi [11] have been reported. Dahn et al. [8] showed that electrostatic discharge sensitivity obtained for ener- getic materials is dependant on the combination of electrodes configuration and circuit structures of the test devise. Thus, the methodology of the test is a key factor as widely varying min- imum initiation energy values for the same explosive may be 0304-3894/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2006.03.043