The Effect of Sample Containers on the Ignition Temperature of Sulfur/Chlorate Mixtures
D. Chapman and J. E. Fletcher
ABSTRACT: In this communication we report the lowered thermal stability of sulfur/chlorate mixtures in contact with glass surfaces. Ignition temperatures as low as 100 °C were found in glass test tubes and are about 15 °C less than for the same mixture in a cardboard fireworks tube.
Keywords: chlorate, sulfur, thermal stability, ignition temperature, glass
Ref: JPyro, Issue 11, 2000, pp72-74
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Shell Altitude vs. Mortar Length
Ron Dixon
Introduction: During the mid 1980’s, I was the President and General Manager of San Diego Fireworks, Inc. At many of our Pyrotechnic Safety and Training Seminars, I was asked about the correlation between mortar length and altitude attained by aerial shells. Further, I have overheard many theories relating to a “vacuum” created within a mortar, if that mortar is longer than some optimum length. Others have made statements indicating that exceptionally long mortars would project shells well beyond “normal” altitudes for given sizes of shells. Upon reaching saturation of these various theories, our staff decided to perform some basic tests to see if any of these theories had merit. Prior to making the determination to conduct this field test, we had the opportunity to view videotape produced by a Japanese firm. This videotape showed shells being fired from a thickwalled glass mortar. Our observations indicated that there was a considerable amount of gas generated by the lift charge and that the vast majority of this gas was produced well after the shell had left the open end of the mortar during launch. Although our methods were not purely scientific, in that we did not use precise measurement recognized in the industry as acceptable and would be able to determine if the theories were in fact accurate or erroneous. We were not looking for precise data, but data sufficient to determine if these theories warranted further investigation.
Ref: JPyro, Issue 11, 2000, pp70-72
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Study on Various Polyesters as Binders for Pyrotechnic Composition
J.P. Agrawal*, S.N. Singh, D.B. Sarwade, V
ABSTRACT: Two tracer compositions were formulated based on magnesium, strontium nitrate and sodium nitrate with unsaturated non-halo and halo polyesters as binders. They were characterized for mechanical properties, thermal behaviour, burning rate, luminous output, and impact, friction and spark sensitivities. The data show that the composition with chloropolyester as binder is better for tracer compositions.
Keywords: polyester, halopolyester, binder, tracer composition .A. Mujumdar & NT Agawane
Ref: JPyro, Issue 11, 2000, pp65-69
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Forensic Testimony: “Matches”, An Over-Inference of Data? A Giglio Obligation?
Frederic Whitehurst
ABSTRACT: The expert witness who over-infers his data through the misuse of adjectives of comparison opens himself up to cross-examination that can and will discredit his work product. This paper uses the example of forensic analysis of black powder explosive to demonstrate that one can not categorically “match” one Black Powder sample to another or very often one complex chemical system to another and that even if this were possible, such “matches” may have limited probative value. The paper also explores the legal obligation of the expert to reveal to the prosecutor, court and trier-of-fact the limitations of the probative value of the evidence where those limitations might be considered to be exculpatory information.
Keywords: Black Powder, forensic analysis,
Ref: JPyro, Issue 11, 2000, pp53-62
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Pyrotechnic Particle Morphologies — Metal Fuels
K. L. & B. J. Kosanke and Richard C. Dujay
ABSTRACT: The morphology (size, shape and surface features) of the constituent particles in a pyrotechnic composition affects its performance. This is particularly true of metal fuel particles in the composition. Particle morphology can also constitute an important part of forensically establishing a match between materials of known origin and evidence. This article catalogs and briefly discusses some characteristic features commonly associated with metal fuels in pyrotechnic compositions.
Keywords: morphology, metal fuels, forensics, pyrotechnics
Ref: JPyro, Issue 11, 2000, pp46-52
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Propellant Chemistry
Naminosuke Kubota
ABSTRACT: Propellants used for pyrotechnics are composed of energetic materials that produce hightemperature and high-pressure gaseous products. The propellants are classified into three types by their physical structure and the ingredients used: (1) homogeneous propellants consisting of chemically bonded oxidizer and fuel components in the same molecule, (2) heterogeneous propellants consisting of physically mixed oxidizer and fuel components, and (3) granulated propellants consisting of energetic solid particles. While the energy content of a propellant is determined by the chemical properties of the ingredients, the physical properties and chemical processes of the ingredients determine the ballistic characteristics such as burn rate and pressure and temperature sensitivities.
Keywords: propellant chemistry, activation energy, burn rate
Ref: JPyro, Issue 11, 2000, pp25-45
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