Archive for January 2007

Review of: The Chemistry of Fireworks by Michael S. Russell

Review of The Chemistry of Fireworks
Michael S. Russell

Review by Paul Smith

Michael S. Russell’s treatise on the chemistry involved in the composition of display fireworks is a welcome primer on the chemistry of pyrotechnics. While this book was written for the student with ‘A’ level qualification or equivalent, it has potential for use in a college level general chemistry course. (The British ‘A’ level equates to Advanced Placement (A.P.) coursework at the high school level in the United States.) Russell’s 12 chapters cover the basic devices safety, and British regulations and standards. Chapter 1 includes a seven-page glossary of pyrotechnic terms designed to help the person reading pyrotechnic literature for the first time. Some of the definitions are quite brief and do not completely explain some key terms. Stars are defined simply as “a compressed pellet of explosive composition designed to be projected as a pyrotechnic unit”. This definition excludes two major forms of stars—rolled and cut. This reviewer found the glossary helpful in translating some of the British terms for fireworks; terminology is not always the same. For example, the U.S. pyrotechnician would know the burster as the burst charge or composition, the British term for lift charge is propellant, and U.S. terms Quick match and Black Match are called piped match and quick match, respectively in Britain.

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Ref: JPyro, Issue 12, 2000, pp69-70
(J12_69)
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Comment on: “Shell Altitude vs. Mortar Length” by R. Dixon

Shell Altitude vs. Mortar Length
R. Dixon

Review by Clive Jennings-White

Ron Dixon has presented results on the correlation between the altitude achieved by a 3- inch (76-mm) shell and the length of the mortar from which it was fired. Provided that the mortar length was at least 18 inches (457 mm), there was no further gain in shell altitude with increasing mortar length. My own anecdotal observations are entirely in accord with Ron Dixon’s measurements, provided that a commercial Black Powder lift is used. However there may be more to the old pyrotechnists’ wives’ tale of increasing shell altitude with increasing mortar length than these measurements suggest.

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Ref: JPyro, Issue 12, 2000, pp68
(J12_68)
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Review of: Experimental Composite Propellant An Introduction to Properties and Preparation of Composite Propellant Design, Construction, Testing and Characteristics of Small Rocket Motors by Terry W. McCreary

Experimental Composite Propellant An Introduction to Properties and Preparation of Composite Propellant Design, Construction, Testing and Characteristics of Small Rocket Motors
Terry W. McCreary

Review by Terry W. McCreary

There are many references available to address design, construction, and evaluation of chemical propulsion devices. Terry McCreary has provided a fresh look at the science and specific processes associated with development of ammonium perchlorate composite propellant (APCP) solid rocket motors in his recently selfpublished book, Experimental Composite Propellant. There is little content in this book that Journal of Pyrotechnics, Issue 12, Winter 2000 Page 69 has not already been explored in other publications, but presentation of the material has never been more kind to the reader.

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Ref: JPyro, Issue 12, 2000, pp68-69
(J12_68)
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Fixed and Scanning Infrared Radiometers for Combustion Studies

Kathy Underhill-Shanks and M. Keith Hudson & Matthew J. Russo

ABSTRACT: The feasibility of using lead selenide (PbSe) detectors and simple electronic circuitry, including a 600 Hz chopper and chopper frequency/ phase reference circuit, to detect infrared emissions from flames and rocket motor plumes was demonstrated. A fixed wavelength radiometer, employing one-inch interference filters and mechanical phase adjustment, was constructed to monitor the 4.4-µm carbon dioxide band and the 2.7-µm water vapor band. The fixed wavelength radiometer was used in flame studies and in several rocket motor tests. The design of the fixed wavelength radiometer was modified to produce a spectroradiometer. The spectroradiometer system included a circular variable filter (CVF) having a wavelength range of 2.1 to 4.7-µm, which allowed wavelength scanning. The circuitry for the spectroradiometer was improved to include a time constant, which could be adjusted electronically, and an electronic phase adjustment. The spectroradiometer was used to monitor numerous rocket motor firings. The infrared emissions detected by the spectroradiometer included: the water vapor band at 2.7 µm, the hydrogen chloride band at 3.5 µm, and the carbon dioxide band at 4.4 µm.

Keywords: IR radiometer, rocket plume monitoring, PbSe detector, engine health, combustion diagnostics, infrared spectroscopy, IR emission


Ref: JPyro, Issue 12, 2000, pp57-67
(J12_57)
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Practical Applications of Capillary Extrusion Rheometry to Problems in the Processing of Energetic Materials

Roy E. Carter

ABSTRACT: Energetic materials are manufactured by processes involving flow, often under conditions of elevated temperature and pressure. Such processes include extrusion, casting and pressing. If the manner in which the material flows under these conditions is not well understood, production and quality problems may result. A capillary extrusion rheometer is essentially a laboratory-scale extrusion press that is highly instrumented and accurately controlled. As such, it provides an ideal tool for studying and quantifying the properties of the materials as they flow under conditions likely to be encountered in practice. Additionally, the extruded output from the instrument may be subjected to further testing such as for mechanical and ballistic properties to relate changes in processing conditions to product properties.

Keywords: processing, extrusion, filling, analysis, rheology, rheometry, flow, viscosity


Ref: JPyro, Issue 12, 2000, pp52-56
(J12_52)
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Studies of the Thermal Stability and Sensitiveness of Sulfur/Chlorate Mixtures Part 4. Firework Compositions and Investigation of the Sulfur/Chlorate Initiation Reaction

D. Chapman, R. K. Wharton, J. E. Fletcher and A. E. Webb

ABSTRACT: Fireworks formulations were modified to produce compositions containing sulfur/chlorate mixtures, and their thermal stability and mechanical sensitiveness were studied. The results indicate that the presence of sulfur/chlorate mixtures in fireworks compositions reduces the ignition temperatures to values well below those obtained with compositions that do not contain the sulfur/chlorate mixture and generally increases the sensitiveness (this was particularly marked in iron-containing mixtures). The sulfur/chlorate initiation reaction was examined and the mixture was shown to produce sulfur dioxide on heating. Once formed, the sulfur dioxide quickly causes potassium chlorate to decompose and pyrotechnic mixtures containing potassium chlorate to ignite.

Keywords: chlorate, sulfur, sensitiveness, thermal stability, ignition temperature


Ref: JPyro, Issue 12, 2000, pp43-51
(J12_43)
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An Introduction to Chemical Thermodynamics Part 2—Entropy, Molecular Disorder, and the Second and Third Laws

Barry Sturman

ABSTRACT: This is the second in a series of articles, prepared at the request of the publisher of this Journal, presenting an introductory outline of chemical thermodynamics and chemical kinetics, with emphasis on those aspects of particular relevance to pyrotechnics. The First Law of Thermodynamics, which was the subject of the first article, cannot explain the direction of change in the physical world. The Second Law of Thermodynamics states that spontaneous change is always associated with an increase in the entropy of the universe. The universe is simply the system of interest plus its surroundings, assumed to be isolated from external influences, while the entropy is a thermodynamic state function. Much of this article is taken up by a discussion of entropy. The relationship between entropy and spontaneous change is clarified when entropy is interpreted as a measure of molecular disorder. The Gibbs Free Energy is a thermodynamic state function that allows the entropy change in the system and its surroundings to be predicted from the thermodynamic properties of the system alone. It provides the basis for predicting the direction of change in chemical systems. Finally, the Third Law of Thermodynamics states that the molar entropy of a pure substance is zero at the absolute zero of temperature. This is developed from Boltzmann’s relationship between entropy and the number of molecular arrangements consistent with the properties of a system. It is shown how the Third Law permits the calculation of absolute values for the molar entropies of pure substances.

Keywords: thermodynamics, entropy, free energy


Ref: JPyro, Issue 12, 2000, pp31-42
(J12_31)
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A Survey of Analytical Tools for Explosion Investigations

K. R. Mniszewski & R. Pape

ABSTRACT: Practical analytical techniques that have been found to be useful in explosion investigation include: timeline analysis, experimental data comparisons, thermochemical code analysis, TNT and other air blast equivalency techniques, ground shock analysis, dynamic gas concentration estimates, simple fuel/air explosion codes, damage pattern analysis and system safety analysis methods. An example application of existing analytical tools to an explosion investigation is presented. Exotic analytical techniques are available but are not justified unless the loss is very large. Methodology is reviewed for completing a reasonable explosion investigation, including essential items from NFPA 921. Needs are addressed for desired technology advancements.

Keywords: explosion investigation, thermochemical equilibrium, blast equivalency, system safety analysis, ground shock


Ref: JPyro, Issue 12, 2000, pp16-30
(J12_16)
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Pyrotechnic Particle Morphology—Low Melting Point Oxidizers

K. L. Kossanke, B. J. Kosanke & Richard C. Dujay

ABSTRACT: The morphology (size, shape and surface features) of the constituent particles in a pyrotechnic composition affects its performance. While this is particularly true for high melting point fuels and oxidizers in the composition, to a lesser extent it is also true for those with low melting points. Particle morphology also constitutes an important part of establishing the likelihood of a forensic match between evidence and materials of known origin. This article catalogs and briefly discusses some morphologic features often associated with some of the most commonly used low melting point oxidizers in pyrotechnic compositions.

Keywords: morphology, oxidizer, forensics, pyrotechnics, potassium nitrate


Ref: JPyro, Issue 12, 2000, pp5-15
(J12_5)
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Speculation on the Effects of Gunshot or Explosive Residues on Historic Silk Flags

Charles S. Tumosa

ABSTRACT: Historic battle flags and uniforms are collected by museums, and many have significance as icons representative of their owners as well as historic context. The effects of battle, both mechanical and chemical, have an impact on the projected lifetimes of these objects in museums website here. Modern air quality, as well as the type of display, is important. Pyrotechnic displays using Black Powder can also produce considerable amounts of particulates and gases and, if near museums, may be a significant source of damage to a museum’s collection.

Keywords: gunshot residue, explosive residue, silk flag, Black Powder


Ref: JPyro, Issue 12, 2000, pp1-4
(J12_1)

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