The cover price is US$25.00. This book contains 106 pages.
Timing Aerial Shell Bursts for Maximum Performance
and Safety |
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The time chosen for the interval between a shell firing and its burst
is sometimes given less thought than it deserves. By carefully choosing
the delay interval provided by the time fuse, it may be possible to
produce undistorted bursts, with a higher level of safety. |
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Aluminum Metal Powders Used in Pyrotechnics
[This article is an updated, enlarged version of one originally appearing
in Pyrotechnics Guild International Bulletin Nos. 27 and 28
(1981–82).] |
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Of those chemicals used in pyrotechnics (with the possible exception
of charcoal) aluminum metal powders have the ability to produce the
greatest variety and range of effects. Thus, mastery of the use of aluminum
in pyrotechnics offers both a challenge and a reward. In an attempt
to assist in achieving that mastery, this article presents information
on aluminum metal powders and their use in pyrotechnics. However, the
emphasis is on physical aspects of aluminum metal powders, rather than
on aluminum chemistry. The subject of specific uses of aluminum in pyrotechnics
has been covered by other authors, and numerous references to such articles
are given in the last section of this paper. |
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Explosions and Detonations |
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The proper use of technical and scientific terms is fundamentally
important for clear and effective communication. It is also a mark of
a professional to use the vocabulary correctly. Toward that end, the
following brief article is offered. |
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Fireworks Displays Abnormally Dangerous
Activity ? ? ? |
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Most of the fireworks display industry is aware of the ruling of the
Washington state supreme court, which declared the conducting of fireworks
displays to be an abnormally dangerous activity. In part, that ruling
was based on their considered opinion that, by their very nature, fireworks
displays could not be performed safely. One ramification of declaring
fireworks to be an abnormally dangerous activity is that in the event
of an accident, negligence is no longer a consideration regarding liability.
In legal parlance this is referred to as “strict liability”.
Under normal liability, in order to win a judgment it must be shown
that a defendant was negligent (i.e., failed to conduct himself as a
“reasonable” person would have under the same circumstances).
Thus, if a display operator and crew always do what reasonable persons
would, they would not be negligent and would be victorious if sued.
(At least this is true in theory.) However, under strict liability,
about all that a plaintiff needs to prove in court to win a judgment
is that they were injured. Obviously, this is a far easier task, and
a situation likely to have ramifications affecting insurance rates and
a sponsor’s willingness to put on displays. |
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Lancework Pictures in Fire |
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Lancework set pieces can be one of the most interesting forms of fireworks.
If one uses high-quality lance formulas, skillfully designed lance figures,
provides clever animation, or tells an interesting story, the entertainment
value of lancework can reach the heights it should. This article describes
the methods used by the authors to design, construct and display lancework
set pieces. There are also short appendices written by C. Jennings-White,
M. VanTiel, and R. Winokur, wherein they present their views on some
points relating to this article. |
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Successful Bidding and Performance on Government
Fireworks Display Contracts |
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Over the years the authors have had experience with government contracting
from both sides: in selecting and monitoring contractors for the government
and as holders of government contracts. In this article we would like
to share some general information about contracting with the federal
government and about contracting for fireworks displays in particular.
However, readers are cautioned that there are some differences in the
manner in which various government departments let contracts and then
monitor those contracts. Thus there is no guarantee that the process,
as described in this article, is completely accurate for any particular
situation. |
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Electric Matches & Squibs |
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The terms electric match and squib are often used interchangeably
in the fireworks industry. However, there are at least two good reasons
not to do this, one technical and one legal. Technically, these are
two different items both in terms of form and function. Legally, although
both are Class C explosives (Explosives, 1.4g), squibs are on the BATF
Explosive Materials List, which invokes all the regulatory requirements
normally reserved for display fireworks, blasting caps and dynamite. |
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"Skip Burning" of Visco Fuse |
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In late December 1978 more than 100 serious injuries were reported
in eastern Kentucky, apparently the result of defective visco fuse.
The defective fuse had been used by a manufacturer of M-80’s and
other illegal consumer devices. These devices “exploded as soon
as they were lit”, apparently while still being held in the hand.
While the authors’ interests were peaked by this report, it was
not possible to investigate the cause of the malfunctioning fuse because
none was available for testing. Many years later, while discussing the
accidents at the 1989 PGI Convention, Eldon Hershberger said that he
had a small amount of fuse dating back to approximately that time, and
the fuse had an unreliable burn rate. He stated that the fuse generally
burned normally, but every once in a while the burning seemed to instantly
advance ½ to 1 inch. He had purchased the fuse from a hobbyist
supplier in the late 1970’s. This sounded like it might be the
defective fuse we wished to have for testing. Eldon was kind enough
to supply two short lengths for evaluation. |
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Electric Ignition of Shock Tube Firing Systems
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NOMATCH™ is a new system for igniting fireworks that replaces
quick match with shock tube plus flame-to-shock (or electric-to-shock)
and shock-to-flame attachments. The system was introduced by B &
C Products, Inc., with a press release included in the July 1994 Issue
of American Fireworks News, an article in the July 1994 issue
of Fireworks Business, and a demonstration and seminar at the
1994 Pyrotechnics Guild International (PGI) convention. There was considerable
discussion, among the PGI convention attendees, of the potential usefulness
of this new system in various fireworks environments. The safety and
performance advantages of the system seem obvious. Below is a brief
discussion of two low cost alternatives for electric ignition of shock
tubing. For the most part, these are well known and commonly used methods;
however, probably not among those in the fireworks trade. It is hoped
that this information is interesting and possibly will aid in the introduction
of this system. |
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The Role of the Expert Witness |
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There is a good deal of misunderstanding as to the role of the expert
witness in our legal system. Because of this; because I think the subject
is intrinsically interesting; and because no one else has chosen to
present the subject in an article for the fireworks trade, I have decided
to make an attempt at an explanation. However, it should be understood
that I have not made a study of law or of our legal system. Accordingly,
while I believe I am correct, I can only give my understanding and belief
as to the proper role of the technical expert witness. |
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Measurement of Aerial Shell Velocity |
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In addition to satisfying general curiosity, there are technical questions
requiring knowledge of aerial shell velocity. For example, a calculation
of how far down range aerial shells will have traveled at various times
after having been fired from highly angled mortars requires knowledge
of the shell’s muzzle velocity and its effective drag coefficient.
In particular, the authors (along with Mark Williams) plan to determine
the maximum horizontal range of aerial shells which burst after the
normal time fuse delay. This study could be conducted empirically by
firing different size shells from mortars at various angles. However,
such an approach could be prohibitively expensive and time consuming,
and it probably would not allow the examination of as many cases as
desired. As an alternative, the question could be examined us-ing a
computer model of aerial shell ballistics. This would be relatively
inexpensive and any combination of shell velocity, shape, and mass;
time fuse delay; and mortar angle could be considered. However, without
verification using results from actual testing, the modeled results
would always be at least a little suspect. Ac-cordingly, the best choice
is to conduct a number of field tests to verify the correct performance
of the computer model, and then to model the cases of interest. This
article is the first in a series, which will describe the down range
study introduced above. |
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Control of Pyrotechnic Burn Rate |
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There may be many times when a fireworks manufacturer will want to
adjust the burn rate of pyrotechnic compositions. Sometimes this may
be for matters of esthetics and other times for safety. For example,
all of the following are unacceptable:
• Strobe stars that flash with so low a frequency that they fall
to the ground still burning.
• Color stars that burn so rapidly that they occasionally explode
when a shell flowerpots.
• Rockets that fail to lift-off because their thrust is too low.
• Rockets that explode upon firing because internal pressures
exceed the casing strength.
• Salutes that burn like fountains instead of exploding with violence.
• Flash powder that explodes when uncon-fined, even in small quantity.
In each case, taking action to adjust burn rate should solve the problem.
Depending somewhat on how they are counted, there are at least 15 factors
that control pyrotechnic burn rate. A manufacturer that understands
how these factors act to affect burn rate may better anticipate when
product performance difficulties will occur. Also, such a manufacturer
will be better prepared to modify product formulations to correct any
problems that do occur. Each of the burn rate control factors act by
affecting one or more of the following: activation energy, heat of reaction,
and efficiency of energy feedback. In this paper, the 15 factors are
presented, explained and examples given. |
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Hypothesis Explaining Muzzle Breaks |
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Muzzle breaking aerial shells continue to be a significant cause of
serious injury for persons discharging display fireworks. The problem
is greatest for manually fired displays, where the person igniting the
fireworks remains in close proximity to the mortar. Over the years,
many possible causes for muzzle breaks have been suggested. Unfortunately,
most of these explanations are incapable of withstanding close scientific
scrutiny, and there has been no published study that has tested any
of the potential explanations. Without knowing the cause(s) for muzzle
breaks with some certainty, it is difficult (or impossible) for a manufacturer
of aerial shells to know what measures might be taken to reduce or eliminate
the chance of their occurrence.
Probably the best known characteristic of muzzle breaks is that they
occur almost exclusively in the largest diameter (most potentially dangerous)
aerial shells. Probably at least 90% of muzzle breaks occur in aerial
shells 205 mm (8 in.) or larger. This is true, even though at least
90% of all aerial shells fired are smaller than 205 mm (8 in.). Thus
any theory for the cause of muzzle breaks must account for this observation.
The authors hypothesize that either setback or very small fire leaks
lead to the occurrence of muzzle breaks, and that the dynamics of the
propulsion of fireworks from mortars and the explosion of aerial shells
is such that the chances for muzzle break occurrence is greatest for
large diameter shells. In an attempt to test the hypothesis, a series
of measurements were performed to determine the exit times of aerial
shells from mortars and the times to explosion of shells after internal
ignition. Results of these measurements are each somewhat surprising;
they tend to support the hypothesis and provide insight into the mechanisms
of aerial shell flowerpots. |
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Basics of Hazard Management |
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The consequences of accidents can be dev-astating to those immediately
involved and their relatives. However, the ramifications of accidents
can extend much further. This is illustrated in what Richard Green (Idaho
National Engineering Laboratory) has described as
“ The Four Horsemen of Our Own Apocalypse”, specifically:
ACCIDENTS, INJURIES, LITIGATION, and LEGISLATION.
In effect, this is a chain in which Accidents produce Injuries, which
often result in Litigation, the notoriety from which helps generate
pressure for more restrictive regulation (Legislation). With this view,
it is accidents involving individuals that produce increased regulation,
or at least provide an excuse for increased regulation. Because regulations
not only affect those individuals having accidents, but also the fireworks
community as a whole, the whole community has a stake in eliminating
fireworks accidents. It is the hope of the authors that this article
will contribute by stimulating thought and discussion of some basic
Hazard Management concepts. |
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Safety Rating System for Pyro-Chemicals |
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