A Collection of Essays by Bill Ofca
REVIEW OF THE BASICS
A general review of basic safety considerations for fireworks makers is
perhaps overdue. The new-comer amateur or pro can especially benefit from the
safety facts of this pyro-chemical art and science. Years of hard earned
experience, mistakes, and tragedy should not be relearned in bits and pieces.
This only invites history to repeat its tragedies. Nor does space in AFN allow
an in-depth and fair study of this vast subject. However, a look at some basics
may inspire readers, with a thirst for more knowledge, and a desire for future
existence to do research and ask questions.
It must be borne in mind that any mixture of oxygen and fuel, under the right
conditions, may explode if it ignites. It must be also remembered that fireworks
mixtures are mixtures of chemically bound oxygen and fuels in solid form. It is
therefore the responsibility and duty of all fireworks makers, from the hobby
mixer to the industrialist pro, to take all steps to prevent accidental
ignition. The second most important duty is to limit exposure by preventative
means, should accidental ignition occur. This means limitation of quantities
being worked on, and isolation of all other quantities of explosives. It also
means to limit the number of workers on an operation to the bare minimum
required, and to isolate the operation from accidental propagation to all other
operations on the premises.
Almost all the ingredients used in fireworks compositions are used as finely
divided powders, which greatly increases their surface area in a given volume
and/or density. For example, a charcoal dust cloud in air explodes violently
when ignited. Therefore, all finely divided mixtures of materials should be
handled with care. This is especially important with finely divided metals,
which are hard enough to cause friction ignition. Finely divided metals present
a hazard to violent explosion when ignited, and are susceptible to ignition by
static electricity more easily than other mixtures due to their conductivity.
Steel tools must be avoided in grinding, mixing, charging, pressing, tamping,
ramming, or other similar loading operations. Steel tools create sparks when
struck. The almost as hard bronze, may be used for certain purposes, but the
much softer brass and lead are safer. Wood and aluminum tools, and mallets made
of rawhide are also non-sparking safe.
Potassium chlorate, in many ways one of the best fireworks ingredients, may
under certain conditions of temperature and acidity, slowly break down giving
chloric acid, or chlorine dioxide, both of which are more active oxidizing
agents than potassium chlorate itself. When this happens, potassium chlorate
mixtures are extremely hazardous, with disastrous results often occurring.
Sensitivity to heat, shock, friction and impact are greatly enhanced with
ignition occurring, in some cases, as little as a flick of the fingernail.
Sulfates, sulfides, and sulfur itself may be slowly oxidized to form sulfuric
acid, which can then break down the potassium chlorate into dangerously active
chloric acid.
Places where plain mixing is done containing sulfur, (but no potassium
chlorate;), must be kept separate from the places where chlorates are mixed.
This separation also applies to personnel, clothing, tools, and utensils, which
should be thoroughly washed between operations. No chlorate should ever be used
with ammonium salts because of the probability of forming ammonium chlorate,
which violently explodes at the temperature of boiling water (212 degrees F).
All the oxidizing agents, when mixed with finely divided metals, should be
handled with extra care and respect.
Carbon, (in the form of charcoal, lampblack, or carbon black), potassium
nitrate, and sulfur mixtures, seem to be fairly safe to handle. Barium nitrate
also seems fairly safe when mixed with sulfur, carbons, or finely divided
metals. Finely powdered metals, in mixtures with barium and strontium nitrates
and potassium perchlorate, even when sulfur is present, appear to be fairly
stable mixtures. It is reported, the sensitivity of such mixtures is increased
by the addition of powdered charcoal. There is no doubt charcoal does indeed
speed-up the burning rate of some mixtures, and also lowers the surface ignition
temperature of certain mixtures. There is some evidence that mixtures containing
both potassium perchlorate and asphalt gums, cause the perchlorate to be changed
into the chlorate, with disastrous results during storage. Asphalt gums should
be avoided with perchlorates or chlorates because the asphalt gums contain
sulfur and sulfur acids, which break down the chlorates to chloric acid.
The smallest amounts as possible should be used when experimenting with new
compositions, as the slightest incident can turn a mixture into an explosion.
Magnesium metal powder should be avoided by the inexperienced pyrotechnician.
This metal must be treated with special coatings to avoid spontaneous combustion
before it can be safely mixed with oxidizers. Magnesium cannot form a protective
metal oxide layer on its surface as aluminum can.
Mixes of any type of aluminum powder, potassium nitrate and sodium oxalate,
with water, will often heat;-up, and can result in spontaneous combustion.
Atomized aluminum, because of its strong aluminum oxide outer layer, appears to
be far less reactive than other aluminum powders in mixtures known to react with
aluminum.
Titanium seems to be relatively safe in regard to spontaneous ignition, and
has not been reported to cause such problems. Finely divided titanium powder or
dust, is a fire and explosion hazard by itself, when dry. For this reason
titanium dust is packed wet (with water) in sealed drums for shipment. Titanium
dust has no useful purpose in fireworks due to its hazardous nature. However, in
granular form (sponge), it is used to make many beautiful sparking effects.
Titanium is an extremely hard metal, and as such, poses a friction;-ignition
hazard. It especially increases the sensitivity of mixtures containing chlorates
or perchlorates. Extra care must be exercised when ramming devices such as
whistles, gerbs, fountains, etc., that contain perchlorates and titanium.
Ramming of devices containing potassium or barium chlorate should never be
attempted, especially if titanium is an ingredient.
During commercial manufacturing, the amount of chemical composition in a
building at any one time should be kept as low as possible. The workers should
wear non-sparking or conductive shoes. Floors should be conductive as outlined
in the National Fire Protection Agency (NFPA) standard #99. Cotton clothing
should be worn, and all metal machinery and moving parts should be well grounded
electrically, to bleed off static electricity before it can build up a dangerous
charge. No matches should be allowed in the manufacturing area. Change houses or
areas where smoking is permitted will help keep the dangers of smoking under
control. Safety training and periodic scheduled safety review meetings with
employees are required by OSHA. Close supervision during work is essential to
safety.
- WO
ON CHEMICAL SENSITIVITY
Sensitivity of chemical mixes not only relates to how easy (or difficult) one
can "strike fire" by friction or impact, but also involve other
considerations. The level of heat energy required for combustion (ignition
temperature), and whether the chemicals are susceptible to spontaneous
combustion should also be considered. The choice of fuel and oxidizer may very
well be compatible and free of the danger of spontaneous combustion when water
dampened or wet mixed. However, in some instances, the choice of fuel and the
ratio of fuel to oxidizer, can render the same mix sensitive to heat by having a
low ignition temperature characteristic. The lower the ignition temperature, the
easier a spark, (electrical or mechanical), can set it off.
I have often heard pyros say, "Oh, that stuff is safe, its not
sensitive, don't worry!" Compared to what? Everything we measure in life is
relative compared to some standard. So how do we base our judgment on the
"relative" sensitivity of fireworks chemical mixes? Unless you have
access to a good explosives engineering library, a lot of money for special
apparatus, a lot of time to set-up and conduct experiments, and a good education
to interpret the data of your findings you can't make an accurate judgment on
relative sensitivity.
Attempts at establishing practical measurement standards are being made and
that's good! (See AFN #15, Oct. '82, pp5 "Impact Sensitivity;" by L.
S. Oglesby). However, the fireworks industry generally does not have any
practical standards of sensitivity measurement other than government specs for
military signals. For the most part, the work of professionals and amateurs
alike has relied on the knowledge (or hearsay) of those who are experienced and
willing to share their knowledge. Unfortunately, there are, and always will be,
those who work in the "dark", without regard or ability to conduct
controlled experiments for determining relative sensitivity.
Be it a question of chemical compatibility or heat, friction, shock, and
impact sensitivity;; we must presume an inherent and intrinsic danger exists by
treating all chemical mixes with equal care. It can be dangerously misleading to
use the words "never" and "always". However, when handling
fireworks chemicals, we must never trust in the unknown and must always respect
what is known.
The following is a list of chemical combinations known to cause sensitivity
problems. Next to each listing are letters to indicate the types of sensitivity.
The code key is given as follows:
F = Friction
HY = Hygroscopic
I = Impact or Shock
SP = Spontaneous Combustion
U = Unstable (poor shelf life, slow decomposition or unpredictable)
AVOID THESE COMBINATIONS OF CHEMICALS
1. Potassium Chlorate & Sulfur, Sulfides, or Sulfates - F, I, SP, U
2. Barium Chlorate & Sulfur, Sulfides, or Sulfates - F, I, SP, U
3. Potassium or Barium Chlorate & Ammonium Compounds - F, I, SP, U
4. Potassium or Barium Chlorate & Calcium Carbonate - F, I, U
5. Potassium or Barium Chlorate & Aluminum - F, I, U
6. Barium or Potassium Nitrate & Aluminum (when wet) - U, SP
7. Ammonium Perchlorate & most Nitrates - HY, U
8. Untreated (coated) Magnesium & any Oxidizer - SP, U
9. Barium Nitrate & Sodium Oxalate - HY, U
10. Barium or Potassium Chlorate & Sodium Oxalate - HY, U, F, I
Readers are invited to contribute additional chemical combinations known to
cause any sensitivity problems (and the reasons) for future publication. Mail
any comments to:
Bill Ofca
c/o B&C Associates
66 Holt Road
Hyde Park, NY 12538
THE PROFESSIONAL DISPLAY OPERATOR
What is a professional display operator;? (Hint: the emphasis here is on
professional;). He is a person thoroughly familiar with the most important
aspects of the responsibilities associated with the safe handling,
transportation, and use of exhibition fireworks. He knows not only the how-to
and rules, but the reasons why specific directives exist.
A true sense of pride and accomplishment can be enjoyed through the proper
handling and control of display fireworks. Likewise, when rules are ignored or
broken, the consequences can be serious. Those who operate public fireworks
displays belong to a rare and unique "brotherhood" of professionals.
Again, the emphasis is on professional. The training and experience a display
operator receives, when reflected in responsible attitude, behavior and actions
on every display, allows the title to be fitting and deserved.
The professional display operator will be respected as professional when his
conduct and attitude shows he is a respectable person. Think about it! When a
stranger approaches him on a display, is he polite and does he show any manners?
That stranger might be the customer, a politician, a display committee member,
etc. That stranger might also be a relative or close friend of any of the above.
Does the display operator avoid the use of foul language in public? People
nearby have ears and fireworks events are usually family type entertainment
affairs. Even the common spectator tells stories, often exaggerated beyond the
bounds of truth, to their friends and relatives.
Are YOU a display operator;? During a display, the eye of the public is upon
you! Ten thousand pairs of eyes are focusing in on you, off and on, as evening
approaches. Giving someone the finger, or pulling a moon is definitely juvenile.
Likewise, reckless horseplay and fighting among the display crew does not show
maturity or professionalism. Smoking near the fireworks set-up also looks bad.
You may know its safe (if it really is), but those watching will think you are a
reckless menace. Drinking beer in public before a display is definitely
forbidden. Not only does it look bad, it is bad. In many states, it is against
the law for display operators to drink alcoholic beverages before or during a
fireworks display. Local ordinances may include an open container law forbidding
drinking in public. Many display sponsors post signs forbidding spectators from
bringing beer to the displays. How outraged do you think the sponsor will be if
you are spotted drinking a beer? It is grounds for charges of criminal
negligence in the event of an accident, no matter what the cause. Do you show
respect for the display sponsor and his committee workers?
The display sponsors (customers) have the final authority when you are in
their territory. They are paying big bucks for a good display, which includes
your services. In other words, you are his paid servant and the spectators are
guests. If you respect the relationship of this arrangement, customers will
always treat you with dignity. After all, they understand you are the expert in
your field, and they need your services to present the display. Likewise, the
professional display operator is aware that repeat business depends on how the
customer perceives him. - WO
WHOSE JOB IS DISPLAY PLANNING?
With July 4th, 1986 now history, it appears there were more tales of public
display accidents than ever before. I wonder if that's true or only seems that
way because of the heightened awareness of this year's insurance crunch. One
thing is for sure: the accidents that did happen received intense media
coverage, especially by newspapers. Most of the stories either mentioned or
focused on the insurance situation while suggesting inevitable law suits. There
is nothing like "fanning the flames" to make the industry look bad!
Perhaps the reported public display accidents were not as many as the
negative media reporting would lead one to believe. After all, there were tens
of thousands of displays exhibited on July 4th across the nation. Yet one
accident is one too many. Year after year, the fireworks industry has taken a
"beating" from the news media. Accidents at public displays are
preventable.
When a serious accident occurs, it is usually the result of several safety
rules, not just one, being ignored and broken. The errors may even be traced
back to the factory at the assembly table, with everyone along the way sharing
some of the responsibility. If the display sponsors and the shooters do their
jobs, public injuries can be avoided, even if a bad shell is experienced. All of
the rules of shooting are more or less premised on the assumption that fireworks
are somewhat unpredictable and the next shell could be a bad one. From
barricading the mortars to placement of the spectators, the set-up should
consider public safety first, with those what-if situations thoroughly thought
out. The consequences of every choice must be thought out. We are free to
choose, but we are not free to avoid the consequence of a bad choice.
Public safety is the responsibility of all parties involved, not just the
shooters on display night. Jobbers, shooters, and manufacturers must insist on
quality work from their production facilities. Cheap shells only invite
accidents in the field. The customer must be educated by the salesman seeking a
signature on the display contract. The salesman should be an experienced shooter
and knowledgeable in all display set-up situations. A customer must be taught
what his responsibilities are. Important safety concerns should be bound in the
contract. For example, safe distances from the mortars to the spectators, parked
cars, inhabited buildings, etc. Defining the responsibility for a rope line,
crowd control, fire protection, police protection, auto parking, clean-up of the
site after the display, etc., should all be detailed in the contract.
The customer must be made to understand his cooperation is essential to the
planning and success of the display because, after all, it is his display. If
there is an accident that he could have helped avoid, it will come out in the
trial. The customer will be sued along with anyone who had anything to do with
producing the display. Lawyers name everyone. If the customer doesn't know what
to do or how he can help, it won't get done.
The display salesman, the shooter's crew chief, and the customer, should all
meet at the display site a few weeks ahead to plan the display, check and
measure distances, establish where the rope line will be, and discuss what to do
about wind and wind direction, fall out ash, etc. A set of written rules and
guidelines should be given to the customer. All the customer's crew men should
get a copy of these safety rules and concerns. To take for granted the customer
knows how to plan a successful safe display is a serious breach of
responsibility. Every display site should be reviewed in person to assure
conformity within the law, and common sense safety for the size of the display
and the size of the crowd. - WO
SHELL SPIKING IMPROVES SAFETY
"Spiking" is the term used by shell makers for binding a cylinder
shaped aerial shell with twine. The twine is usually wrapped around the shell
from end to end vertically, and then spirals down the side to where it is tied
with a clove hitch knot. Generally, most shells have at least
eight or more equally spaced vertical spikes (or double spikes) of twine. The
number of turns spiraling down the side of the shell varies with the type and
size of the shell. Spiking is always applied before a shell is pasted-in.
Spiking is the traditional method of "Italian" shell design. It
comes from the days of making shells by first rolling a "bag" casing
around a wooden former. Discs of cardboard or "chipboard" were
inserted into the bag casing to form the casing ends, which were secured by
folded down, over-lapping paper from the ends of the rolled cylinder. After the
shells were loaded and the last discs (with fuse;) were inserted and secured,
the shells were spiked with strong twine of cotton or flax. It is obvious the
spiking adds strength to the shell and improves the burst spread, but how
significant is shell spiking to safety?
In recent years, most professional manufacturers have phased out laborious
shell rolling in lieu of using inexpensive paper cans. The paper can walls are
more ruggedly constructed than the rolled bag casing, and have impressed many
shell makers to the point of producing "stringless" shells. Those who
remember their trials of designing stringless shells will recall compromises
that had to be made to preclude extensive instances of flower potting when the
shells were fired. The lift charge had to be reduced or heavier paper had to be
pasted-in, or internal as well as external discing, had to be introduced, etc.
For light weight shells, the problem of flower potting may not have occurred.
However, with heavier shells of more complex performance, the problem is
pronounced. Some shell makers overcame this problem by introducing more and more
turns of heavy kraft paper when rolling the shell casing or when pasting-in.
During the 1983 display season, I witnessed approximately 600 four inch color
with report shells perform flawlessly. Each shell was constructed identically
using thin wall (.030") paper cans with: 1/8" thick chipboard discs on
the ends, spiked with strong twine, pasted-in with 4 turns of 60# kraft paper,
and lifted with 2-1/2 ounces of FFA black powder. The shells traveled high, had
wide symmetrical bursts, and the reports ignited, then timed out, and detonated
perfectly at a high altitude.
As an experiment near the end of the season, twenty more shells were made
identical to the first 600 with only one difference: the twine spiking was left
out. Out of the 20 fired, 8 flower potted, 1 failed to ignite the salute after
the aerial burst, and all had burst out the fuse end of the shell casing,
driving the salute at high speed in the opposite direction, sometimes
dangerously toward the ground.
I have concluded the sudden occurrence of flower potting was caused by
inertia of the shell contents and the weakened, unstrung shell ends. The shell
is resting at zero velocity at the bottom of the mortar when, at the moment of
ignition, it accelerates to 100+ feet per second muzzle velocity. The
"g" forces of the shell contents act internally against the bottom of
the shell casing causing it to separate from the shell walls. The shell casing
tends to accelerate faster than its contents, and perhaps, if no lift flame were
present, would exit the mortar empty, partially empty, or severely cracked.
Without twine spiking, the shell would have to be "beefed-up" with
extra pasted-in paper and/or have its lift charge reduced. While this would help
get the shell successfully launched, it does not resolve the aerial burst and
report ignition problem, especially when paper cans are used.
The experiment left no doubt in my mind that shell spiking improves safety.
This is not to say that all stringless shells are unsafe. There are many shell
makers producing good quality stringless shells, and have overcome the problems
mentioned here in their own peculiar ways. However, most of the stringless
shells I have come across were usually lightweight, no larger than 4"
diameter and no heavier than 1.5 lbs. unlifted. The more complex "stringless"
shells I have seen had rather heavy wall paper cans or heavy wall rolled cans,
heavy discing inside and out on both ends of the shell, and were pasted heavy
with extra paper. They also used extra generous portions of commercial FFA black
powder for bursting or used flash bags. All this extra work and material to make
a performing "stringless" shell makes me wonder if any material cost
or labor is saved at all. - WO
THE DREADED DUD
PART 1
Anyone who has operated a public display and experienced the frightening
embarrassment of seeing the tracer sparks of a fired shell die, knows the dread
of a dud shell. Several thoughts race through one's mind: ...will it break low?
(probably not if the fuse died), ...will it come down and hit someone? ME?,
...feet!, do your stuff!, ...shush! I wish the spectators would stop booing so I
can hear where it lands, ...Oh God, I pray no one gets hit, ...here it comes,
...no car roofs please...THUMP! Phew! On the ground safely! ...Get another shell
up quickly, ...find it at all costs later!, ...can't let anyone get it,
especially children!
Then after the show, you find the dud or maybe have to return at daybreak to
search. All the time you are looking, new thoughts creep into your head: was it
only an isolated shell or are there more? ...is it only this type of shell or
will it happen randomly throughout the inventory? ...Why? ...What caused it?
This subject has played on the minds of shell makers, professional and
amateur alike, for as long as aerial fireworks have been made. Yet, very little
has been written on the subject. Many have isolated the problems, and now avoid
the causes with varying degrees of success, including this writer. Others are
still perplexed and curious, maybe even desperate to solve their dud problems.
In this continuing series on the subject, we will examine some of the
apparent causes of the dreaded dud and what some shell makers are doing to avoid
the problem. The purpose will be to present and share varied opinions
objectively so that readers may form their own opinions and conclusions, or
investigate this controversial subject further.
If we broadly define a dud shell as the result of a malfunction that caused
the shell to deviate from normal performance or intended design during lift
(firing), than we can identify duds in four categories:
1. The "flower pot;" effect
2. Time delay fuse ignition failure
3. Time delay fuse failure after ignition
4. Shell burst ignition failure after time delay fuse burn through
In subsequent issues of American Fireworks News (AFN), we will attempt to
look at each of these categories objectively, while presenting some of the
reported possible conditions that may create the dreaded dud. The subject is
controversial because it addresses the heart of reasoning behind the decision of
some professionals in areas of shell design such as: discing technique, shell
pasting, time delay fuse orientation to the lift charge, and whether or not to
cross match time delay fuse, etc. We will briefly state facts and present some
design techniques and allow you to form your own conclusions. We hope to
stimulate the thinking process. (To be continued ...)
- WO
THE DREADED DUD
PART 2
In part one of this continuing series, we can easily agree the dud aerial
shell is a common safety concern of all shell makers, pros and amateurs alike.
In broad definition of the dud, it was said we can place the phenomenon in four
categories: (1) the flower pot shell, (2) time delay fuse ignition failure, (3)
time delay fuse failure after ignition, and (4) internal shell ignition failure
after fuse burn through.
The Flower Pot Shell
The flower pot shell gets its name from the visual effect of a giant flower
bouquet. From the launching mortar, the observer sees a vertical blast of colors
in a column in which the colors spread while ascending, to create a flower
bouquet pattern. The cause was the shell exploding in the mortar or within a few
feet of the mortar muzzle. If the shell was a salute or contained flash report
effects, a real danger of the mortar exploding is a possible consequence. (A
good practice of many experienced display operators is to shoot ordinary flash
salutes (aerial maroons;) only from cardboard mortars. There have been observed,
many factors, or perhaps combinations of factors, which are possible causes of
the flower pot shell. Some of these conditions are as follows.
1. Too much black powder lift charge can release excessive shearing forces
around the shell that tear at the shell edges, exposing the shell contents to
the lift flame. It has also been suggested, the rapid acceleration of the shell
causes compression of the shell contents (.i.set back;) against the shell
bottom, creating interior shear. Another possibility is set back compression of
shell contents, friction, or impact, causing stars to collide and ignite,
especially when potassium chlorate stars are present. This is an excellent
reason why shells should have their contents packed tight during assembly, with
no moving parts.
2. Lift charge particle size may be too small. Generally, FFA grade
commercial black powder is used to lift cylinder shaped shells. Smaller grain
powders burn quicker and can create the same problems of too much lift charge.
NOTE: Sphere shaped ball shells from the Orient are lifted with smaller grain
powder than FFA but the sphere shape makes a much stronger shell casing than a
cylinder. Ball shells can take the harder acceleration and pounding presented
with small grain black powder.
3. Paper and Paste: Not enough paper pasted around the shell, improper
pasting technique, inferior paste, or wrong paper for ".i.pasting;-in",
have all been suggested as possible causes of the flower pot shell. A shell of
weak wall strength has flower pot potential.
4. Inferior strength on the end of the shell exposed to lift. Most shell
makers are using paper cans these days. With proper design, the paper can shell
can be made with dignified performance. Some shell makers place a cardboard or
chip board disc on both ends of the shell. Some disc only the lift end. Some
place a disc inside and outside the paper cap of the can. Others disc only the
outside, while still others disc only the inside. There are variations within
each technique, such as disc thickness, double discing on the outside of the
shell or combinations of discing with paper tape sealing or glue sealing. All of
the above techniques are used extensively and successfully among shell makers.
The key factor is to achieve the required strength and flame barrier seal, to
withstand the lift forces when the shell is fired.
5. Improperly sealed time delay fuse, especially if the fuse end of the shell
is also the lift powder end (shell fired with fuse down). Some people use animal
hide glue, some use Elmer's white glue, while still others use hot melt glue.
Whatever the glue, the important factor is to seal around the fuse with a fillet
that has no gaps of even the tiniest pin hole size. A pin hole leak can allow
lift flame into the shell or be the weak spot to allow the lift blast to tear
into the shell. Remember, the lift is encased usually in a "bag"
rolled around the shell (.i.nosing paper;). Even with the time delay fuse on
top, flame gasses from the lift are guided to, and encased around the time delay
fuse by the nosing paper and blow-by space between the shell wall and mortar
wall. One interesting observation is that the many shell makers who use animal
hide glue exclusively to seal time delay fuses, also fire their shells with the
time delay fuse up or opposite the lift charge end of the shell. This is because
of the brittleness of hide glue and its tendency to crack after drying,
especially during the blast of lift. Of course, Roman fuses or "spoolettes"
are always fused up due to the tendency of the powder core to blow through from
the lift pressure and blast.
Proper shell design and close attention to details are necessary ingredients
to eliminating the flower pot problem. Once design details have successfully
overcome the flower pot problem, workers must develop consistent work habits (in
a manufacturing situation) to assure the quality of each shell, thereby
eliminating the random occurrence of the flower pot dud. - WO
THE DREADED DUD
PART 3
In part one of this continuing series, we can easily agree the dud aerial
shell is a common safety concern of all shell makers, pros and amateurs alike.
In broad definition of the dud, it was said we can place the phenomenon in four
categories: (1) the flower pot shell, (2) time delay fuse ignition failure, (3)
time delay fuse failure after ignition, and (4) internal shell burst ignition
failure after time delay fuse burn through.
Time Delay Fuse Ignition Failure
This is perhaps the most controversial aspect of the dud shell phenomenon. It
has been the cause of many heated debates among shell makers who profess their
theories with strong conviction and authority to justify the way they make their
shells. The question is: what's better, firing a shell with the time delay fuse
up or time delay fuse down? It appears there is no right or wrong way to fire a
shell in this regard, as it is many factors that determine the success or
failure of shell performance. However, the shell design and construction
overview may mandate one way or the other in regards to fuse orientation. For
example, I believe most shell makers agree that shells made with spoolettes
(rammed Roman fuse;) should be fired with the fuse up to avoid flower pots due
to the fuse powder core blowing through under lift pressure and blast. Since the
bulk of shells made today are made with the 1/4" diameter Japanese or
Chinese time delay fuse, this discussion will focus on its use.
Some shell makers cross match the time delay fuse on the outside of the
shell, a short distance from the starting end of the fuse. This is done by
piercing the side of the fuse and threading a short piece of black match or
thermolite through the hole. When the shell is to be fired fuse up, a piece of
quickmatch is used to transfer ignition fire from the time delay fuse cross
match at the top of the shell, down alongside the shell to the lift powder
charge at the bottom of the shell. This is called the "pass fire". The
long quick match shell leader fuse is introduced into the nosing paper at the
top of the shell, terminating at the time delay fuse cross match, and tied off
within the gathered nosing paper at the top of the shell. This is surely a
successful and reliable method when assembled properly, yet some disadvantages
have been noted:
1. There is a risk of the fuse leader pulling out of the nosing paper
connection (top of the shell) when shells are handled. For example, when
lowering a heavy shell into a mortar or when handling chained groups or bundles
such as when loading flights (salvos) or finale mortars.
2. Ignition failure can occur if the quickmatch leader only slips, nearly
pulling out of the nosing, and the shell is then loaded into a mortar with the
problem undetected. The shell leader burns and stops, failing to ignite the
cross match, extension quickmatch pass-fire and lift charge. The result is a
live shell hung up in the mortar.
3. Time delay fuse ignition failure has occurred when a defective piece of
black match was present in the cross match hole. During handling, sometimes the
black powder coating on the match cracks, crumbles and falls out of the string.
Misfires in this category are rare, but it has been known to happen upon
examination of the recovered dud.
4. Lift ignition failure has sometimes occurred when the time delay fuse
cross match fired, but the quickmatch extension (pass-fire) to the lift charge
didn't. This can be observed when a shell leader fires, with first a delay equal
to the burn time delay fuse, then the shell flower pots or detonates in the
mortar. Similarly, when the pass-fire does ignite, but for some reason delays
lift charge ignition, low breaking shells have been observed. Again, a pause
between the snap of the shell leader firing and the discharge of the shell from
the mortar was observed, which leads one to suspect the time delay fuse was
burning during the pause. Two conditions have been known to cause this. First,
if string is tied around the time delay fuse and pass fire quickmatch, the pass
fire can be choked if the string is too tight. This will definitely delay the
quickmatch until fire burns through the choke. The second is similar to the
first. If string is tied tight around the shell body to secure the pass-fire
quickmatch, a choke delay is formed beneath, where the string pinches the
quickmatch. If there are multiple chokes in the pass-fire, there will be
multiple small delays that add up.
Some shell makers cross match the time delay fuse and then fire the shell
with the time delay fuse down, in contact with the lift charge. The shell
quickmatch leader enters the nosing paper at the top of the shell and proceeds
down along the side of the shell directly to the lift charge. The side of the
shell in contact with the quickmatch paper piping is dabbed with pasted to
prevent the leader from slipping during handling. The flame of the lift charge
ignites the time delay fuse cross match. If the shell is made properly, and the
time delay fuse sealed well, the risk of flower potting can be eliminated. The
major weakness in this method of time delay fuse ignition is in the cross match.
Dud shells have been examined and found to have the time delay fuse sheared off
at the cross match hole. Apparently the piercing of the side wall of the time
delay fuse (for the cross match;) weakens the wall strength, such that the lift
blast tears off the end of the time delay fuse and cross match. This too is a
rare occurrence but does happen under the right conditions. Some of the
variables that can contribute to this happening can be: amount of lift charge,
placement of the match hole from the end of the fuse, size of the cross match
hole, thickness of the cross match, and how much force was used to insert the
cross match, etc. This problem can be eliminated with using thermolite igniter
cord as a cross matching material. The thermolite is thin and very reliable.
Because it is thin, a much smaller hole can be punched in the time delay fuse.
Caution must be exercised with using thermolite igniter cord;: it is friction,
impact and heat sensitive. Medium speed thermolite seems to be less sensitive
than fast speed thermolite. However, the same precautions need to be applied.
Avoid sources of heat coming into contact with thermolite such as hot melt glue,
etc. Avoid hitting, striking, scratching, stepping on, smashing, and rough
handling, etc., of thermolite igniter cord.
Some shell makers will split and prime the time delay fuse with a slurry of
black powder. The slurry may be in combination with nitrocellulose lacquer or a
dextrin and water mixture. Lacking any experience in this method, I have no pro
or con evidence to convey. However, it should be noted that this is the method
used extensively in the Orient to make Japanese and Chinese shells. The
incidence of dud oriental shells due to the failure of the fuse primer to take
fire is extremely rare, attesting to the success of this method.
It should be clearly understood that there may be many other convincing
factors, both pro and con, to each method of shell making detail, that are
unknown to this writer. The "best" method is the method that
successfully and reliably works for each shell maker. By all means, safety
should be the criteria for judgment. - WO
THE DREADED DUD
PART 4
In part one of this continuing series, we can easily agree the dud aerial
shell is a common safety concern of all shell makers. In broad definition of the
dud, it was said we can place the phenomenon in four categories: (1) the flower
pot shell, (2) time delay fuse ignition failure, (3) time delay fuse failure
after ignition, and (4) internal shell ignition failure after time delay fuse
burn through.
Time Delay Fuse Failure After Ignition
The shell is loaded in the mortar, fuse lit, then "thump"! It's
airborne with a healthy spark tracer from the 1/4" diameter Japanese time
delay fuse. The shell is about half way along its flight to the apex when all of
a sudden the time delay fuse tracer dies. The shell peaks and then falls with a
heavy smack into the ground.
Upon dissection and examination, more often the fuse quit burning at the
point where it passes through the discs and sealing glue. One immediately
suspects a defective fuse due to a break in the powder train. However, this is
unlikely, as the hot burning gases will tend to flash over any small gap. Users
of Japanese time delay shell fuse are generally satisfied with its reliability
and quality. Its performance has established a high confidence level among shell
makers.
Another thought is the glue (perhaps white or similar types) penetrated the
asphalt layer of the time delay fuse (under the outer paper wrap) and
contaminated the powder core. Again, this too is unlikely. I have conducted my
own tests in this regard by submerging several 12" long pieces of fuse in a
gallon of Elmer's glue for 30 days, leaving only 1" of fuse on each end
unsubmerged. After 30 days the container was opened, the fuse removed and test
burned, all without failure. While it is possible an occasional "dead"
spot may appear in the powder core or asphalt layer of Japanese time delay fuse,
it is highly unlikely it would consistently occur at the point where the fuse
passes through the shell end disc. I suspect I am not alone in experiencing this
type of dud situation. (Please note, I am referring specifically to the use of
Japanese time delay fuse, not Chinese. I have found Chinese fuse to be of
inferior quality to the point of unreliable and unsafe. Most of the problem with
Chinese or Taiwanese time delay fuse have been poor quality in the powder core,
mainly due to the chemicals being too granulated and poorly mixed.)
Some people who use hot melt glue to seal the Japanese time delay fuse and
experience core burn out where the fuse passes through the hot melt glue and
disc, will suspect the heat of the hot melt glue causing the asphalt layer of
the fuse to melt and penetrate the fuse core. Not so. I submerged several long
pieces of time delay fuse in our hot melt glue system hopper tank to test this
theory. The molten glue was at 375 degrees F. After 30 minutes, I removed the
fuse and it all performed flawlessly.
Here is the real cause! On properly pasted shells, the paper will be
thoroughly soaked with wheat paste which will be in intimate contact with the
time delay fuse. Until the shell has dried, the water will saturate the outside
layer of paper on the time delay fuse and travel within the paper fibers along
the entire length of the fuse, much like the wick of a kerosene lamp. When the
wetness reaches the inside cross match, (presumed black match;) the cotton
string easily absorbs water and conducts it into the time delay fuse powder
core. The powder core then migrates the water as far as the discs and perhaps
further. As time passes and the shell dries, including the outside of the time
delay fuse, a wet spot remains within the fuse core (you guessed it) at the
point where the fuse passes through the discs. This progression of events was
observed by taking apart shells at subsequent daily intervals after they were
pasted and when not allowed to dry quickly. It was observed the stars also
became wet and mushy in some shells around where they contacted the cross match.
Remember, this does not happen to every shell, but to a percentage at random
throughout the inventory. It was especially prevalent when shells were pasted on
cloudy or rainy days and could not be quickly sun dried.
The obvious answer to avoiding and eliminating this problem is to dry shells
quickly. Sun drying of shells is not a perfectly reliable method in climates
with high relative humidity or when rainy days can occur on a random,
unpredictable basis. The best method is to dry shells in a safe building or room
where hot air is ducted in and circulated, perhaps with the aid of a ceiling
fan. Shells can be thoroughly dried to a crisp within 48 hours with this method.
The air should not be recirculated or ducted back to the hot air furnace as it
will be laden with moisture and only serve to increase the humidity of the
drying room thus slowing the drying process. Fall, Winter and Spring are the
best seasons for pasting and drying because the cooler the air temperature, the
less moisture it can hold. Now, as the temperature of this air is increased, the
capacity to hold moisture increases greatly. On a hot, humid summer day, the air
would have to be heated 20 or 30 degrees F higher than the outside atmosphere to
gain any drying benefit. Thus, the Summer months are not best for shell drying.
If sun drying is the only available method, it is suggested at least 7 days
of rain free drying be allowed for the best assurance against duds in this
category. Remember, the longer a shell stays wet, the larger the dud risk. Also
be aware, too little water in the paste can reduce the strength of the dried
shell wall due to insufficient paste penetration into the paper. Skimping on the
paste is not the answer, fast shell drying is. - WO
THE DREADED DUD
PART 5
In Part 1 of this continuing series, we can easily agree that the dud aerial
shell is a common safety concern of all shell makers. In broad definition of the
dud, it was said we can place the phenomenon in four categories: (1) the flower
pot shell, (2) time delay fuse ignition failure, (3) time delay fuse failure
after ignition, and (4) internal shell ignition failure after time delay fuse
burn through.
Internal Shell Ignition Failure After Time Delay Fuse Burn-Through
When a single break color shell (cylinder shaped) is fired it will usually
spin at a high rate of RPMs as it ascends. When this type of shell is made with
a spoolette or rammed Roman time delay fuse, shell internal ignition failure has
been known to occur. Many shell makers believe the cause of failure is
centrifugal force expelling the flame, sparks and perhaps a loose layer of fuse
powder along the core train, as the shell is fiercely spinning. This is the only
known defect of this kind for spoolettes, and indeed, rare.
On one occasion I had a bad experience with flash bag shells and another time
with salutes. Both involved failure to ignite flash powder. On both shells, I
had used Japanese 1/4" diameter time delay fuse and decided an internal
cross match was not necessary. Boy, was I wrong! When observing a piece of
Japanese time delay fuse burning, one sees a hot flame burst of out the
terminating end of the fuse. This misleads one to believe a cross match on the
terminating end (inside a shell) is redundant. I especially didn't think so
since the end of the fuse was nestled into flash powder. The result was an
average of 5 out of 10 shells dudding (50%)! While the terminating spurt of
flame out the end of the fuse is certainly hot enough to ignite flash, I now
believe the duration of the flame is too short (at least 50% of the time) to
raise the contacting flash powder to ignition temperature. It appears the
temperature and duration of the flame spurt out the terminating end of the fuse
are on the threshold of flash ignition, as the results of 60 shell firings was
exactly 50% failure. In each case, the shells were disassembled and the fuses
shown to have burned through. By following the rule of always cross matching the
shell-internal end of the time delay fuse, I have not since experienced a dud of
this nature in over 25,000 shells.
In this series of articles on, "The Dreaded Dud", I have tried to
remain objective in sharing many ideas and observations. I hope it has
enlightened the thoughts of those who have been "in the dark", or
perhaps has provoked ideas in others who may now investigate the phenomenon from
a more exact and scientific study. Until then, the generalized ideas presented
here will remain conjecture based on the observed evidence. Readers must form
their own conclusions. - WO
CAUSES OF DISPLAY DEFECTS
PART 1
Fireworks defects occurring during a display are defined here as anything
that causes a deviation from a normal intended function. Malfunctions that have
been experienced on occasion are often the fault of an operator such as a
loading and firing mistake, equipment set-up error, or sloppy set piece or
finale assembly work. There are also unpredictable malfunctions as a result of
defective fireworks. The aim of this and future articles is to discuss the
common malfunctions, causes, prevention, or action to take in their event. Both
operator error and material defects will be discussed in the following
categories: (1) low breaking shells, (2) the "flower pot" shell, (3)
dud shells, (4) flight or salvo problems, (5) finale problems and (6) set piece
problems. When these problems occur, it is a rare exception, not the norm.
The intention of these articles is not to get into an in-depth study of
assembly or functional detail, but to isolate common errors and causes of
display problems.
Low Breaking Shells
A shell that breaks low causing colors to fall burning to the ground, or
other effects such as reports to go off on the ground, is usually caused by
insufficient lift pressure in the mortar from which the shell was fired. The
most common reason (on hand fired displays) is, the operator placed the shell in
the wrong size mortar pipe. For example, a 4" shell cannot be put in a
3" mortar but it can be placed in a 5" mortar by mistake. When this
happens, the propellant lift charge gas pressure escapes around the outside of
the shell instead of concentrating its driving energy underneath the shell. The
result is the shell "puffs" out of the mortar, goes about 50 feet into
the air, arches over and then falls toward the ground. The shell will burst low
on its way to the ground scattering burning stars towards the ground. If the
shell was a color with report or a multibreak shell, the remaining effects will
continue to go off on the ground. If this should ever happen, it is imperative
that all shell "ready" boxes or other such containers of live shells,
be kept tightly closed or covered. Anyone on the crew who first notices this
problem must quickly holler out and warn the others. The first sign of this type
of problem-error will be the sound of the mortar at discharge. A
"whoosh" or "foomp" sound should be an alarm signal. The
normal discharge sound is a good cracking report - "thump!", which may
sometimes ring the steel mortar pipe. Experience will teach the new operator the
proper sound, and a low break will definitely sound different and grab
attention. Other causes of a low break shell are a cracked mortar pipe, or too
little lift charge when a shell was manufactured. These causes are very rare,
however, and even a shell with reduced lift charge, when fired from the proper
size mortar, will still achieve a fairly safe altitude when it bursts. If a
mortar is cracked, or the bottom blown open, all shells fired from that
particular mortar will be low breaks. This happens only when shells are
repeatedly fired from an aluminum or heavy gage PVC plastic mortar with a wood
bottom plug. It has never happened with a steel (welded bottom) mortar, except
when shells detonate within. If a steel pipe blows its bottom, it suddenly won't
be there anymore with only a crater left behind. Aluminum or plastic mortars
must never be used as battery mortars, (those reloaded during a hand fired
display;). Steel mortars have been know to develop cracks only if they overheat
while taking a constant pressure pounding from repeated firings. This is why two
3" and two 4" steel battery mortars should be issued on every hand
fired display. By firing alternately between the two mortars of each size,
overheating is avoided. The larger 5" and 6" mortars can absorb and
dissipate much more heat due to their shear mass and surface area. Also there
are fewer 5" and 6" shells in any display compared to the quantity of
3 and 4" shells, which comprise the bulk quantity of display shells.
Lower than normal altitude breaks can occur if a shell is not seated in the
bottom of the mortar when fired. Gas pressure and driving energy is expended in
the void beneath the shell with reduced force to send the shell to its normal
altitude. This problem has been observed when a tight-fitting shell is lowered
into a mortar and then becomes stuck half way to the bottom. It would be insane
to try to push the shell down with a hand or even a tool. If the shell is then
fired to clear the mortar, the result will be a low star burst.
In the next issue, the "flower pot" shell, along with more display
safety tips, will be discussed. - WO
CAUSES OF DISPLAY DEFECTS
PART II
Fireworks defects occurring during a display are defined here as anything
that causes a deviation from a normal intended function. Malfunctions that have
been experienced on occasion are often the fault of an operator, such as a
loading and firing mistake, equipment set-up error, or sloppy set-piece or
finale assembly work. The aim of this continuing series of articles is to
discuss the common malfunctions, causes, prevention or action to take in their
event. The intention of these articles is not to get into an in-depth study of
assembly or functional detail but to isolate common errors and causes of display
problems. In the last issue, low breaking shells were discussed. We now continue
with:
The Flower Pot Shell
A flower pot effect is caused by a shell bursting in the mortar at the same
instant the lift charge has fired. The reason may be due to a damaged or
defective shell that has "weak wall" construction or too
much lift powder. Sometimes a shell will burst as it is leaving the mortar or
just a few feet above the mortar. In any event, the shell is in vertical motion
at a high velocity from the lift charge, which will cause the bursting stars
and/or effects to blossom out in a vertical direction much like a mine shot or
flower bouquet. Multiple break shells, color and report shells, or multiple
report (effects) shells, will usually have their effects go while ascending
vertically. For this reason, flower pot display shells, if they occur, are not
"usually" hazardous. There are two cases where a definite hazard
exists: (1) If a salute is fired from a steel mortar and it should flower pot
(steel shrapnel) and (2) if a hard breaking ball shell should burst just after
it leaves the mortar pipe.
In the first example, this is the reason salutes must never be fired from
steel mortar pipes, only cardboard! If this rule is observed, the danger is
minimized.
In the second example, the hard breaking ball shells burst with equal force
in a spherical direction. If a ball shell flower pots while in the mortar, it
will create a large mine shot in a vertical direction. If the shell bursts
within a few feet of leaving the mortar, it will drive high velocity flaming
stars (bullets) in all directions radiating from the center of the burst. This
is one important reason (of several) the "ready box" or shell
container must be covered or have its lid shut tight as the shells are launched.
In the event a large caliber oriental ball shell bursts within a few feet of the
mortar muzzle, a real danger exist for the operators. Safe distance with remote
electrical firing or the erection of a body-protecting barricade to crouch
behind (such as the Japanese are commonly known to use) are the only real
protection that can be established.
The instance of flower pot shells are rare when good quality shells are
fired. However, they do sometimes happen, even with the best shells. Regardless
of the statistics, you never really know what the next shell is going to do.
Therefore, the thoughtful, professional operator will take the necessary
precautions, as if the next shell fired will be a flowerpot of the worst kind.
And then if it should happen, the consequences may only be disappointment that
the shell didn't make it into the sky.
The next article in this series will discuss "dud" shells. - WO
CAUSES OF DISPLAY DEFECTS
PART III
Fireworks defects occurring during a display are defined here as anything
that causes a deviation from a normal intended function. Malfunctions that have
been experienced on occasion are often the fault of an operator, such as a
loading and firing mistake, equipment set-up error or sloppy set-piece or finale
assembly work. The aim of this continuing series of articles is to discuss the
common malfunctions, causes, prevention or action to take in their event. The
intention of these articles is not to get into an in-depth study of assembly or
functional detail but to isolate common errors and causes of display problems.
In the last issue, flower pot shells were discussed. We now continue with:
The Dud Shell
There are two basic types of dud shells. The first type is when a shell fires
and the burning time delay fuse goes out while the shell is ascending. The shell
does not burst in the sky but instead falls cold to the ground. A slight 5
degree tilt of the battery mortars away from spectators on a windless night will
assure that a dud, should one occur, will drop down range a ways, instead of on
top of the operators or spectators. If there is any wind or breeze, you must
take it into account before set-up. Wind direction and the location of
spectators are very important factors in determining the exact placement of
mortars. Should a dud fall to the ground, it MUST be found after the display at
all costs! If it falls to the ground near spectators, it must be found and
guarded immediately, with the spectators moved a safe distance away until it can
be disposed. Also keep in mind you cannot be sure there were no duds in the
grand finale. It's impossible to track every shell in a finale. Therefore, a
good search of the display site is mandatory after the display. If possible,
return at first daylight to closely inspect the display site and fallout zone.
If you cannot return at first daylight, at least have it in your contract that
your customer must do the inspection before allowing any children into the area.
If you KNOW you have a dud and have not found it on the display night, you MUST
make every effort to locate it at first daylight. Failure to do so may result in
more legal grief than you can imagine with your negligence in the center of the
plaintiff's claim.
When a cold dud is found, the proper way to dispose of the shell is to dig a
hole in a remote place and bury it, out of the way of prying eyes of children.
Some experts claim you should soak the shell in a bucket of water first.
However, if the shell is a plastic one, it should be soaked outdoors in a bucket
of solvent (such as Xylene) until the shell casing is mostly dissolved. The
remaining contents (sludge) should then be buried.
The second type of dud shell is a shell that stays in the mortar after the
quickmatch long-fuse leader has been fired. This type of dud has also been
called a "hang fire". The proper way to handle this problem is to
flood the mortar with water, then dump the soaked shell out of the mortar.
However, this is not always practical during a display and should you decide not
to, LEAVE IT ALONE! Never, repeat NEVER, under any circumstances whatsoever,
attempt to fish a dud shell out of a mortar. NOT with a stick, NOT with
ANYTHING! Just leave it alone. It is not uncommon to see the shell fire by
itself several minutes later. During hand fired displays, NEVER load another
shell on top of the dud to try to clear the mortar. This may cause both shells
to detonate resulting in the mortar bursting. Just leave the dud and its mortar
alone until after the display when you can properly flood it with water. Go to
other mortars to finish the display. This is a good reason to have at least two
mortars of each size. Remember, after flooding the mortar and retrieving the wet
shell, dig a hole and bury it in a remote location.
The next article will deal with flight (or salvo;) problems.- W.O.
CAUSES OF DISPLAY DEFECTS
PART IV
Fireworks defects occurring during a display are defined here as anything
that causes a deviation from a normal intended function. Malfunctions that have
been experienced on occasion are often the fault of an operator, such as a
loading and firing mistake, equipment set-up error, or sloppy set-piece or
finale assembly work. The aim of this continuing series of articles is to
discuss the common malfunctions, causes, prevention or action to take in their
event. The intention of these articles is not to get into an in-depth study of
assembly or functional detail, but to isolate common errors and causes of
display problems. In the last article on this subject, dud shells were
discussed. We now continue with:
Flight Problems
Flights of shells are salvos or multiple shells fired in a group, to
highlight the display like a miniature finale, or to display a sequence of
effects. Flights may contain as little as three shells and as many as twelve
shells. Five shells seem to be common. They may all be the same size or they may
be a mixture of sizes. Some are fired rapidly and some have pyro-fuse delays
assembled into the quickmatch between shells. Sometimes flights of the same size
are hand fired out of one or two flight racks, reloading after each launch by a
flight crew. The most common (and safer) method is to provide a rack of mortars
for each flight and preload each flight into its own mortar rack before the
display.
Hand firing flights is difficult and risky and should be avoided if at all
possible. When done, the rack(s) must be cleaned after firing and before
reloading to prevent harbored sparks from igniting the next flight as it is
loaded. Two flight racks are always better than one. Alternate cleaning and
loading allows time for one rack to cool as another is in use. Flight firing
with this method is spaced throughout a hand fired display thereby allowing time
between the flights for cleaning, cooling and reloading. Extreme caution must be
exercised in the event of a hang-fire type dud that stays in one of the mortars.
If you have only one flight rack on that display, flight firing is then over
until after the display, when the mortar can be flooded with water, and the
shell disposal accomplished. It is difficult to tell if a dud shell was left
behind after a flight is fired with this method. It is not recommended that tape
(for detecting misfired mortars;) be placed over the muzzle of the mortars after
reloading because of the risk in placing hands over the mortars. It is therefore
strongly suggested that one rack of mortars be provided for preloading each
flight before the display.
With multiple flight racks, all the flights may be preloaded before the
display, with misfire detection (masking tape) placed across the mouth of each
mortar. The individual shell leaders should be held down against the outside of
the mortar with string, rubber bands, or tape with a slight loop allowed where
the quickmatch enters the mouth of the mortar. This helps prevent misfires
caused by one shell firing and yanking on the quickmatch connection to the next
shell. When using a rack of mortars for each flight, the flights may be hand
fired or electrically fired. If hand fired, only one crew member is needed to
light each flight in turn.
When single flight racks for reloading are used, the mortars must be made of
aluminum or steel. When one rack for preloading each flight is provided, the
mortars may also be of cardboard. Reloading cardboard mortars is hazardous
because the walls tend to harbor sparks and glow or burn. Spiral cardboard
mortars tend to peel after firing causing a blockage to reloading the next
shell. When this happens, the temptation to jam the shell down with the hands or
a tool is far too great, giving credibility once again to Murphy's Law.
Single flight racks must be trenched in and barricaded on both sides with a
berm of dirt, sand or sand bags. If the ground is too hard to dig, there is a
risk the rack may jump or bounce as the shells are fired. When this happens, one
or more shells may fire at a dangerously steep angle. If a single rack is used,
the support brackets or legs must be anchored to the ground with sand bags or
stakes driven into the ground and nailed to the rack. If multiple racks are
used, the legs or brackets may be joined and nailed together for added support
to minimize bounce. One method is to align the racks such as the rungs in a
ladder and join them by nailing 2 X 4 lumber along the sides. Nails smaller than
10 d should not be used.
As with any aerial shell firing, observe the wind direction before the
display and allow a slight angle tilt on the mortars during set-up to prevent
duds or fall out from dropping on the display operators or spectators. Be
conscious of the end of the rack that will be ignited and what mortar will fire
first. Align the racks so the quickmatch fuse joining shells, burns in a
direction away from the crowd. In this way, should a shell blow in the mortar
and knock over any live mortars, they will point in a direction away from the
spectators.
The next article in this continuing series will deal with ground set-piece
problems. - WO
CAUSES OF DISPLAY DEFECTS
PART V
Fireworks defects occurring during a display are defined here as anything
that causes a deviation from a normal intended function. Malfunctions that have
been experienced on occasion, are often the fault of an operator, such as a
loading and firing mistake, equipment set-up error or sloppy set-piece or finale
assembly work. The aim of this continuing series of articles is to discuss the
common malfunctions, causes, preventions or action to take in their event. The
intention of these articles is not to get into an in-depth study of assembly or
functional detail but to isolate common errors and causes of display problems.
In the last article on this subject, flight problems were discussed. We now
continue with:
Ground Display Set Piece Problems
Experienced problems with set pieces have included the following: (1) Signs
hung up-side-down (2) set pieces that have fallen due to wind or vibration (3)
wheels that come off the hub spindle when a locking pin, nail, or cotter pin was
missing (4) pieces that have cross fired out of timing sequence (5) devices or
sections of a piece that have failed to fire.
Once a set piece is ignited, there is nothing that can be done to correct any
errors. If there are errors, you can only stand there in embarrassment to watch
the set piece fizzle, fail, fall, or if the wheel drops off its spindle and roll
towards the spectators, watch it part the crowd like Moses and the Red Sea.
During set-up is the time to think and inspect for possible problems. Trace the
matching to follow the sequence it will create. On signs and image lance pieces,
look for incomplete connections in the fuse, loose connections at the lance
heads, and any broken lances. Be sure the sign or image is right-side-up and the
starting lead fuse is connected before raising. Also be sure that multiple
frames of a phrase or scene are fuse;-interconnected so all parts of the piece
fire. Inspect wheels for the locking pin on the hub spindle. Unlike lance
pieces, wheels must have all match piping in perfect condition, i.e. no holes or
tears, or the piece may cross fire out of sequence. If you find any holes,
repair with masking tape. Be sure all time delay fuses are secured with string
so they won't jump fire during the initial violent ignition of the piece. Delay
fuses are usually secured with string on the back side of the wood frames.
Inspect all revolving or fountain pieces for loose gerbs or drivers. Secure
devices to frames with string and tape.
Be sure to brace all set pieces so they won't fall due to wind or vibration.
All support masts and braces should be 2" X 4" framing lumber.
Vertical up-rights should be 12' to 16' and angled braces should be at least 8'
and attached to the mast at approximately 5' above the ground. Two angled braces
should be placed 90 degrees apart. Two by four pointed stakes are driven in the
ground at the ends of the angled braces, with the braces then nailed to them.
When set-pieces are a part of a display, operators should plan to arrive at
the display site early to allow ample time for proper assembly, inspection
and/or repairs. - WO
A MATTER OF ATTITUDE
I am the first to admit (to myself for sure) I could have a fireworks
accident. I run that risk every day and am consciously concerned. Yet because of
that daily consciousness, the probability of an accident is considerably
reduced. My concern causes me to take steps and make decisions with regard to
safety first. It has become a matter of habit and a matter of attitude.
At the beginning of each production day, I review the operations with my
partner and co-workers. We look at set-up, equipment, routines, tools,
sequential procedures, etc. Our minds are actively scrutinizing: are we safe?
Did we overlook anything? We often check each other to assure ourselves we are
each properly concerned for each other's welfare. When one of us forgets, the
other is quick to remind. For this reason we usually work in pairs and rarely
alone. We know it's the small details that count. From shell assembly to
cleaning tools, every detail has a reason. And that ounce of extra effort to
carry out the detail is indeed cheap insurance.
Proper human attitude is perhaps the single most important factor in accident
prevention. Accepting personal humility or the act of being humble in the
absence of knowledge is most important to intellectual growth. (The more I
learn, the more I realize how much I don't know). There is nothing wrong with
one admitting he doesn't know, especially when he has reasonable doubt on a
particular subject. This often commands instant respect from others. It's
dangerous to state conjecture or opinions as fact. In the essence of a
professional atmosphere, opinions are meaningless unless you are an established
authority on the subject. Even when generating professional reports, opinions
(if necessary) are reserved for the conclusion of the report and must be stated
as the author's opinion. Saying, "I don't know," goes beyond honesty.
It opens the door to knowledge, personal intellectual growth, and maturity.
On the other hand, arrogance breeds contempt and creates an atmosphere
conductive to accidents. To argue blindly with reality, out of stubborn pride,
can lead to disaster. Some people are overly sensitive and react to reasonable
safety suggestions by easily becoming offended and defensive. Safety discussions
should be encouraged and rewarded with compliments. The topic should be
"neutral territory," free of prideful defensiveness, especially if we
are stopped by a co-worker while in the forgetful act of violating a rule. Don't
get mad if this happens to you, say thanks instead. After all, the person
reminding you is looking out for your life as well as his.
Safety is a matter of attitude and I often wonder: how many fireworks
accidents to date could have been prevented by a simple, open minded, change of
attitude. - WO
PRO FAX
Most of you are probably wondering, "PRO FAX? What happened to SAFETY
FAX?" The truth is I wanted to expand the available subjects to write
about, including of course, safety. I spoke to AFN's editor, Jack Drewes, and we
decided it would be a good idea to write about subjects that have a professional
slant. Since I am a co-owner of a display fireworks manufacturing firm (Ed.
Note: now retired) and have been accused (more than once) of being highly
opinionated (aren't we all?), I am hoping PRO FAX will be much more than
mundane. Jack and I decided that this timely feature should appeal to the many
professional operator subscribers of AFN as well as the amateur interest in
professional current events.
PRO FAX will feature safety articles as in the past but will now also include
expanded coverage of business events with the emphasis on professionalism. I am
especially looking forward to writing about subjects such as professional
display operator career development, how-to articles, the financial analysis of
a display, inside tips of how to maximize profits, and how to reduce liability
risks. I hope to stimulate controversy in some areas and maybe report some of
the reader reactions to hot topics! I would also like to impress readers with
the incredible "would you believe...." type features and I invite
readers to write to me with details of incredible experiences involving
fireworks, either pro or amateur. You can write to me at:
B & C Associates
66 Holt Road
Hyde Park, NY 12538
I promise all correspondence will be kept confidential to protect the guilty
as well as innocent! Also, if you would like to have me research and write about
any particular subject, I will be honored to read your request.
Next month, PRO FAX will feature a discussion of interest to all fireworks
display shooters.
- WO
WHAT ABOUT FLASH?
Of all the thousands of variations available in the elements of fireworks,
flash powder is perhaps the most spell-binding fascination to capture the
attention of most pyros. Perhaps this is due to the high energy, awesome nature
of its effects. The blinding white flash, sometimes followed by a cluster of
titanium sparks, then followed by a gut tickling sound pressure wave, is
somewhat exciting to say the least. The remarkable aspect is that flash powder
is relatively inexpensive and simple to manufacture when compared to stars, for
example. Fireworks makers (in the U.S.) use more flash and report components in
aerial shells than any other single device or color.
When accidents involving flash powder occur, the high energy, violent
performance of flash results in serious and catastrophic damage. In recent
times, the legal as well as illegal fireworks trade has experienced the (high
incidence) tragic loss of human life with almost all involving devastating flash
powder explosions. The problems that lead to "accidental" disaster are
all too common: complacency, carelessness, forgetfulness, apathy, contempt, and
blind trust ("it won't happen to me, never has, therefore never
will"). Those who fit this last category, the never-never people, cop a
narrow minded attitude of "don't confuse me with facts, my mind is made
up!" Notice that all these categories are products of the human mind:
attitude and awareness. Can it then be questioned: are the "accidents"
occurring from these problems really accidents? I think not. Irresponsible
attitudes where safety is compromised can only be truthfully stated as
negligence. When a bolt of lightning strikes the powder shed, - that's an
accident;!
Lets examine some facts about flash and some safety tips on handling. A good
quality flash has a critical mass of about 50 grams (less than 2 ounces). This
means it will detonate with concussion in open air (no container), when ignited.
Less than 50 grams will burn violently but without report. Compare this with
black powder which has a critical mass of about 500 pounds!
A three inch aerial salute (2-1/2" X 2-1/2") containing about 4
ounces of flash, when ignited and if held in the hand, will dismember the human
torso, not just a hand. Large salutes are very lethal;! The thought is rather
horrifying, yet we must be realistic to understand the nature of the beast. Be
thinking about this and the safety rules before you blend your next 10 pound
(160 ounce) batch!
In a recent demonstration of the power of flash, a 1 pound bag was detonated
electrically inside a wood structured shed. The blast and fireball was awesome!
The shed was demolished with chunks scattered around where it once stood.
Imagine 100 pounds of flash in an accident;! Instantly lethal in a 25 foot open
air radius, and lethal up to several hundred feet if hit by missiles propelled
from the blast. Windows will break for a 1/4 mile radius, and buildings will
sustain structural damage to window and door frames up to 600 feet away.
Buildings within 200 feet will sustain structural damage to framing timbers.
Think about this: as the size (density) of the flash charge doubles, the force
(or energy;) of the blast increases 8 times!
Here are some do's and don'ts on handling flash;:
1. Do mix outdoors only in humid weather .i.;(above 50% relative humidity;)
to reduce the hazards of static electricity sparks.
2. Do wear only cotton clothing when mixing flash.
3. Do remove all jewelry and all metal including belt buckles.
4. Do spray yourself down and all tools, tables, etc. with Anti- Static Spray
(aerosol cans). This material is amazingly effective in eliminating the chances
of static electricity from ever occurring. I have personally tested this
material while observing the results on a sophisticated electrostatic field
strength meter. Anti-Static Spray is available in cases of 12 cans from Chiswick
Trading, Inc. 31 Union Ave., Sudbury, MA 01776-0907. Similar material can also
be purchased in super-markets and is known as Static-Guard laundry treatment
spray.
5. Do screen all chemicals separately to remove lumps. Never screen flash
powder after chemicals have been blended! The risks of friction ignition should
always be avoided. A second and very real reason for avoiding screening any
mixtures containing large quantities of conductive aluminum powder, is that the
resulting aluminum dust cloud can and does generate static charges. Although
humid conditions reduce the risk here, a life is not worth the risk.
6. Do mix flash on a large sheet of paper, rolling the pile of pre-screened
chemicals as diagonal corners of the paper are lifted and pulled towards the
center. (This is also known as the diaper method of mixing;). This method is
common throughout the explosives industry (not just fireworks) and is practiced
with making many types of sensitive explosives)
7. Do add the titanium last after most of the mixing of each batch is
complete.
8. Do mix outdoors, isolated, away from people and buildings.
9. Do limit batch sizes to no more than 10 pounds (it's now an ATF
regulation) or to the smallest batch needed to satisfy your requirements if less
than 10 lbs.
10. Do limit to one batch and one worker in the work room when charging
salute casings.
11. Do remove all charged casings from the work room to a magazine before
introducing a new batch of flash to the same work room.
12. Do wear a dust respirator when mixing flash or charging it into salute
casings.
13. Do clean up any chemical or flash powder spills immediately, especially
if titanium is present.
14. Don't store bulk quantities of multiple batches in the same container,
i.e. drums, etc. The larger the container, the heavier and harder to handle,
which can result in catastrophic consequences if dropped.
15. Don't mix in plastic bags. (static)
16. Don't store in plastic containers!
17. Don't use plastic scoops or utensils - use only wood or aluminum.
18. Don't screen flash after blending chemicals. Never screen any formula
with titanium present.
19. Don't mix, handle or use flash formulae containing potassium chlorate,
especially if sulfur, antimony sulfide or titanium are included.
20. Don't mix indoors where aluminum dust suspended in the air can be ignited
by the electric spark of appliances or light switches. The resulting blast has
been known to level buildings such as in a gas explosion.
21. Don't smoke, even in a safe area, if your clothes are contaminated with
flash powder.
22. Don't expose too many workers to flash operations. Limit the number of
workers to only those necessary to complete the assigned task (usually 1 or 2).
Keep all operations in separate sheds or limit one work room to one operation at
a time. -W.O.
THE STATIC SEASON IS UPON US!
With the approach of winter comes cold dry air out of the Arctic. The dryness
in the air is an essential cause of the increased occurence of static
electricity build-up on people and objects. When the air is humid, the water
vapor in the atmosphere helps to keep the static charge voltage low by
"bleeding" off any "excess" electrical charge above a
certain threshold established by the level of relative humidity and the laws of
nature. As the humidity drops, the build-up of static electrical charge (and its
electrostatic field voltage;) increase. When the charged object or person comes
near or in contact with another person or object of opposite polarity charge or
ground potential, a discharge of the electricity will occur. This is when we see
a small blue spark, feel a slightly uncomfortable tingle and perhaps hear a
faint snapping sound.
Static electricity discharge is, without a doubt, the most hazardous
phenomenon in the fireworks and explosives industry. We can control the use of
non-sparking tools and keep cigarette smoking, open lights and sources of flame
out of the work place, thereby maintaining our sense of control. However, static
electricity is somewhat difficult to see coming (without sophisticated
instrumentation to warn of a build-up) and in most workshop environments it is
impossible to predict. We can, however, take some rather simple steps to
minimize or prevent the occurrence of static problems.
Anyone who mixes fireworks chemicals that contain conductive charcoal,
aluminum or other such chemicals should take precautions to guard against static
electricity hazards. The use of humidifiers in the workshop (at least 2 in a 20'
X 20' room) greatly reduces the risk. A good relative humidity gage is helpful,
and if you use one, make it a rule to not work, especially with powders, if the
relative humidity falls below 40%.
It is also a good idea to wear only 100% cotton clothing such as denim and to
watch out for visitors who may be wearing sweaters, nylon articles or other
static producing synthetic materials. Keep a few spray cans of anti-static
laundry treatment spray on hand and use it liberally.
Avoid carpets on the workshop floor. Install a conductive anti-static floor
if you can afford one. Insist that workers purchase and wear conductive shoes.
Install a conductive wall plate (connected to a good earth ground source) near
the entrance door and insist everyone touch it as they enter or after they
remove static generating overcoats. A thin chain curtain hanging in the doorway
(also attached to earth ground) can accomplish the same.
Avoid the use of plastic materials and containers that can generate static
charges. Use instead, paper or cardboard containers.
Install aluminum or copper cladding on the work bench and electrically ground
through a 100 K ohm resistor (to prevent an arcing static discharge).
All of these are good working solutions to avoiding the hazards of static
electricity and should be practiced for assuring a safer work environment. - WO
CHLORATES AND THE SUN
We have often heard the warnings, KEEP CHLORATES AWAY FROM THE SULFUR
COMPOUNDS!!! It's been said so often that a "ban potassium chlorate
paranoia" has crept into the minds of many a pyro. I personally believe
that potassium and barium chlorate do indeed have a place in making fireworks as
long as mother nature's chemical rules are strictly followed. As Dr. Takeo
Shimizu states so well in his book, Fireworks - The Art, Science and Technique,
1981, p. 90, "It would be ideal to reject this material (potassium
chlorate;) from fireworks, but it is quite difficult even at present, because no
other oxidizer can surpass potassium chlorate in burning speed, in ease of
ignition or in noise making, using the smallest amount of composition."
Potassium chlorate is also an ideal oxidizer for colored stars because it
produces a high temperature flame, rich in chlorine atoms, which intensify
colors. This allows commercial fireworks manufacturers certain economics as
well. One thing is for sure, chlorates are here to stay. Fortunately, advances
in the learning and sharing of knowledge within this industry over the past 30
years, have lead to a decline in the number of accidents involving the
chlorates. There probably aren't any professionals worth their salt today that
are not aware of the ingredients that sensitize barium and potassium chlorate.
Even so, there are those that go so far as to promote the use of a few
percentages of barium carbonate as an acid neutralizer (buffer) in meal powder,
and then dust their chlorate stars with this primer.
Accidents attributed to the use of the chlorates should not be blamed on the
chlorates but to the carelessness of the user. Perhaps the user was ignorant of
the "potential" dangers or if he knew, he forgot, or was apathetic. In
which case his future in this life and industry is limited. We've seen a lot
written on the dangers of chlorate mixtures with sulfur, sulfates, sulfides,
ammonium compounds, etc. But I haven't seen too much written about the dangers
of ultraviolet light, - the sun!
From time to time, we see articles written, or hear someone talk about the
(unconditional) merits of drying fireworks in the sun. Certain conditions do
exist where the sun can be a direct cause of a pyro disaster. Sulfur reacts with
water to create a weak form of sulfuric acid (H2SO3). Potassium or barium
chlorate reacts with sulfuric acid to form chlorine dioxide (ClO2) which is
decomposed explosively by sunlight into chlorine and oxygen. If there are any
fuels present, spontaneous combustion is a definite certainty! Think about this
the next time you are considering sun-drying chlorate stars dusted with meal or
pulverone, barium carbonate or not!
Chlorates demand to be understood. Beginners to the art should definitely
avoid fooling around with the chlorates until they understand the nature of the
beast. There are many other warnings and cautions regarding chlorates and their
incompatibility with other substances besides those mentioned here, which make
them potentially dangerous. (See also "On Chemical Sensitivity", page
5). However, in the hands of trained professionals, chlorates have for many
years produced some of the most beautiful effects offered in the fireworks art.
- WO
IS STAPLING QUICKMATCH HAZARDOUS?
The practice of stapling quickmatch with a staple gun has gained popularity
over the last decade. The introduction of the Hansen Tacker staple gun to the
display fireworks trade rapidly grew in popularity among operators as a fast and
easy way to secure quickmatch to lance work set pieces. It appears the vast
majority of operators have never experienced any accidental ignition of
quickmatch using this method and it therefore follows reason that many would
find other uses of the staple gun to expedite work. One such use has been to
fasten quickmatch finale chain to the wooden frame of a finale mortar rack.
Common sense would dictate the user to be aware that staples are made of steel
and to avoid shooting staples near nails, other staples or hard knots in the
wood. Any ferrous metal striking a hard surface can produce sparks, which
increases the risk of quickmatch ignition. Of course, this line of thinking
presumes the black powder within quickmatch is, in itself, impervious to
ignition from the impact of a staple. Recent events indicate the contrary.
Everyone has heard of "Murphy's Law;" which states: "If
something can go wrong it eventually will." The consequences of Murphy's
Law in the fireworks industry can be extreme. If something bad can happen, it
often is too late when we find out i.e. too late for the victim of the bad
event. However, the rest of us MUST learn from the example if we are to prevent
an identical recurrence of Murphy's Law.
Perhaps many of you have learned of the tragic death of a fellow display
operator in Las Vegas last December (1984). After a lengthy and thorough
investigation, the cause of the accident was determined as the impact of a
chiseling staple against the black powder composition of quickmatch. The
operator had been loading the finale and was leaning over a mortar when the
match took fire from a staple shot from a staple gun. Samples of the match were
tested for the presence of potassium chlorate and potassium perchlorate by an
investigator, with none found. Samples of the match were also tested for impact
ignition. After many unsuccessful trials, ignition was eventually achieved. It
is theorized that the spring loaded impact of a staple gun can concentrate an
enormous amount of impact energy into the tiny surface area at the points of a
staple hence creating the conditions for impact ignition of standard black
powder within quickmatch. (Ed. Note: see following article "New Facts On
Staples", which zeros in on the most probable cause of this tragic
accident;).
Contrary to popular belief, standard commercial black powder can indeed be
set-off by severe impact. It is true that in normal and even rough handling, the
occurrence is extremely rare. However, it has been proven black powder can be
initiated from the impact of a bullet in ballistic tests. For this reason, it
makes sense the concentrated impact energy at the points of a staple could do
the same. About six years ago (1979), I had a conversation with an operator who
told me he had set off an entire finale (on a display in Connecticut) during the
afternoon of the display date. He said it happened when he shot a staple into
quickmatch to secure it to the wooden finale rack. No one was hurt in that
incident and I have not heard of a similar accident until the recent tragedy in
Las Vegas. What has astounded me is the similarity of claims from the
investigations of both of these incidents. The operator of the Connecticut
display swore to me that his staple that caused ignition did not hit any other
metal, and he had cleaned the rack of old staples before set-up. In the Las
Vegas investigation, a lone staple was found protruding from the finale rack in
front of the mortar that discharged to cause the fatality. No other metal was
found in the vicinity of that staple. I for one, am now convinced an inherent
hazard does exist in this practice. Since this controversial topic has surfaced,
I have heard from several sources, stories of a similar nature involving lance
ignition on set pieces during assembly with a tacker staple gun.
The source of ignition with lances can be: upon impact of the staple with the
quickmatch;; impact against the lance head or upon piercing the lance head and
penetration of the column of powder within the lance. Those with experience
stapling quickmatch to domestically produced lances will attest to the hard,
solid nature of the black powder primer-plug at the head of the lance. The
hardness of the prime, which extends approximately 1/4" deep into the lance
tube, appears to vary from lance to lance. I have seen the primer plug on some
lances shatter from the brittleness upon impact of a tacker staple. On other
lances within the same set-piece, the staple will penetrate without so much as
cracking the primer plug at the lance head. The color formula of the powder,
under the lance head primer, may involve oxidizers notorious for impact ignition
such as barium chlorate, potassium chlorate, or potassium perchlorate. I was
recently asked, "Does a tacker staple have enough impact energy to ignite
the color composition inside a lance after penetrating the quickmatch and primer
plug?" Perhaps, and especially if a particular lance has a shallow or soft
primer plug. We must also consider the staple is rapidly decelerating from the
moment it leaves the gun and penetrates the quickmatch. In any event, the impact
compression and crushing of oxidizer crystals will, under certain conditions,
cause ignition. The hard primer plug on some lances offers the greatest
resistance to the impact of a staple. For this reason, I believe it is the most
likely place ignition will occur if it does occur.
Common sense dictates exposure must be limited if lance work is to involve
the use of a tacker staple gun. Work outdoors at a safe distance and down wind
from all other sources of explosives. Do not clutter your work area to impede
your escape in the event of accidental ignition. Move finished pieces a safe
distance away from the work zone (up wind;). Wear cotton or nonflammable and
non-meltable clothing. Keep a bucket or two of water nearby.
A trite cliche states: "History is doomed to repeat itself." This
thought manifests itself in Murphy's Law. No doubt there are staple shooting
display operators who will not see this article, or who will refuse to heed the
warnings that an inherent hazard exists when stapling match to racks or lances.
They may be blinded by self-serving motives to save an extra few ounces of work
effort. After shooting tens of thousands of staples without incident, they may
be thinking ignition can't happen. Perhaps the shooter in Las Vegas thought the
same, or perhaps it was the first time he shot a staple into match. I suspect
the "old timers" to this trade have experienced these same concerns
when they lectured their apprentices on the proper use of twine. I have seen
some of them shake their head and scowl at "new" ideas or methods.
Perhaps in their wisdom from many years of experience, they recognize the
importance of harmony with nature;'s fireworks rules. - WO
NEW FACTS ON STAPLERS
The Hansen Tacker staple gun has seen a resurgence of use in the fireworks
display industry this season. A supplier to the professional fireworks industry
reports the 1988 fireworks season has been the busiest ever seen for the Hansen
Tacker . Orders were backlogged for 6 to 8 weeks last Spring. This stapler is
popular for lance work quickmatch assembly, and if used, should be restricted to
only that use. Also, it should be used only outdoors with plenty of room to
escape, should there be a rare accidental ignition of the set piece while using
the tacker. (Ed. Note: See previous essay).
Many of you readers will recall a few years ago the tragic death of a fellow
display shooter in Nevada. He was assembling the grand finale of a fireworks
display, using a Hansen Tacker staple gun, when a 3" shell suddenly
discharged striking him in the forehead.
There was much talk and writing at the time about the source cause of
ignition with much speculation on many theories. The quickmatch shell leader had
apparently ignited as the display operator was firing a tacker staple into the
quickmatch, attempting to secure it to the mortar rack's wooden frame. Most
everyone agrees that black powder is nearly impossible to ignite with impact or
friction and the rare circumstances that it can happen are severe (i.e.
high-speed bullet impact;). Examination of the rack at the time revealed there
were no other staples, nails, or even knots in the wood to provide a hard
surface to cause the staple to spark. Black powder (especially dusty black
powder on quickmatch;) ignites easily from a spark or incandescent energy
source.
During a recent conversation with the general manager of a staple
manufacturing business in New Jersey, a more probable theory has come to light.
When told the story of what happened in Navada, this gentleman said, "Oh
hell, that's easy to understand! The Hansen Tacker is constructed in the same
manner as most staple guns. A spring loaded anvil is released from a cam to
strike the staple forcing it out the guides into the work piece. If you were to
fire a staple gun in the dark, you would see the sparks that sometimes follow
the staple. The sparks are created by steel against steel, the anvil against the
staple or the friction of the staples riding in the guides before it leaves the
gun. For some industries, this is one of the reasons we copper clad some of our
staple products." (This particular manufacturer does not make staples for
the Hansen Tacker;). This idea now raises suspicion that a spark was generated
in the tacker and it followed the staple into the quickmatch.
Display operators who use staple guns of any sort, beware!-WO
GIVING AWAY THE STORE
The serious amateur one day decides the back yard lab, and back yard
displays, are not fulfilling his "calling" to the art. Like many
before him, he may seek shooting experience with a professional company or he
may go directly into the jobbing business. "Jobbing" is a word that
describes a display contractor who is not primarily a manufacturer. (He may add
to his displays some or, at times, many of his special back-yard-lab shells for
fun or imagined advantage. A jobber sells and shoots public fireworks displays.
He is a contractor, but does not have a plant or factory, and may not even have
a storage magazine. He probably stores his shooting equipment and mortars in his
back yard, and can handle one, maybe two displays (with hired help) on the same
day. He is most likely to be a part-time pyro, who does not depend on fireworks
for his sole source of income.
This "imagined" advantage is usually born out of a lack of
confidence and experience with designing and shooting displays. The new jobber
believes he must load up the show with an excessive shell count, and perhaps
excessive shell sizes, for the allowed display budget. He thinks this will
launch him into pyro stardom, and beget a host of new customers on this new
reputation, born out of "giving away the store". Nothing can be
farther from reality.
First of all, it must be understood that no business ever succeeded by giving
away its goods and services. The practice of overloading a display with shells,
can only serve to outrage those who depend on fireworks for a living. It should
be understood that competition is stiff and pricing of product is depressed in
this industry. In other words, there is not a hell of a lot of money in this
business to begin with. Those who make money do so after working their buns off
on a continuous basis.
When displays are overloaded with shell count, the customer expects this on
every display of the same price in the future. If the jobber cuts the shell
count in the future (presumably to then make money) his reputation will suffer,
and he may not recover to remain in business. If the jobber continues to
overload future shows and, in effect, works for nothing but the fun and pride,
he will either burn out, or burn his bridges. His source of commercial shells
will get wise to his raping the market, and suddenly he can't find a supply of
shells to do his displays. Remember, it has taken years for the industry to
condition customers to price / display size ratio.
If the jobber keeps on overloading his displays, he will definitely acquire
more displays requiring him to spend more money for equipment and probably hire
shooters. Because he has been overloading displays, his profits are very low or
non-existent. Therefore he will be overwhelmed by the expenses and forced to
turn down the business. Those who go blindly ahead, borrowing money to make ends
meet, are eventually forced to fold. There are many stories floating around
about jobbers who don't pay their bills to the shell manufacturers and trade
suppliers. Perhaps their fate was the same described above. Those jobbers who
have gone this route, leave the market in a mess to be cleaned up by those
successful professionals, who depend on fireworks for a living. It's not easy to
pick-up the pieces and reconstruct a customer's trust, while trying to convince
him he should accept a legitimate proposal for a display that has 40% less
shells than last year.
So what's fair? The fireworks business is no different from any business.
Mark-up and profits are always seen as percentages by banks, accountants,
business course professors and successful businessmen. The percentages are close
to the same for all successful businesses, whether fireworks or something else.
Basically we are talking about two price structures. The wholesale and the
retail. Wholesale is the price the middleman pays the manufacturer. Retail is
the price the final customer pays the middleman. Jobbers are middlemen. When
manufacturers fire displays, they are also "acting" as the middleman.
Wholesale prices are doubled (marked up 100%) to establish retail price. Another
way to look at this is wholesale prices are 50% of retail prices. Both are
mathematically equal statements. This is true for just about all merchandising
businesses. The middleman takes his expenses out of the 100% mark-up, and what
is left are his profits. When the manufacturer acts as his own middleman when
selling displays that he will also fire, he has the advantage of making mark-up
on his products to get to the wholesale price, and then mark-up again to the
retail price. He can be more flexible with bidding or negotiating situations,
but remember, he generally has a great deal more overhead than the jobber. The
advantages are only apparent and temporary. Neither the manufacturer nor the
jobber has any competitive edge over the other. If everyone who is involved with
selling fireworks displays, both manufacturers and jobbers, would adhere to the
golden rule of selling at retail, there would be less cut-throat and more
profits for everyone. The design of the display, including insurance cost,
should add up at retail price to the customer's contract price. - WO
ON THE SUBJECT OF ACCIDENTS
What is an accident;? An undesired event that results in physical harm to a
person or damage to property. An accident is, by dictionary definition, "A
happening that is not expected, foreseen, or intended. An unfortunate occurrence
or mishap." Accidents are certainly unfortunate when they occur but are
they really unexpected or unforeseen?
A research firm in Hartford Connecticut recently reviewed more than 11,000
industrial accidents and found several reasons for predicting accidents in
almost all the cases reviewed. What they found was: improper maintenance, lack
of any maintenance program, no written procedures for operating equipment, no
procedure for periodic testing of controls, little or no concern for operator
training, absence of any education or training program, improper installations,
improper applications, no maintenance records, no use of log books, and little
or no common sense.
ALL accidents are caused (natural catastrophes excluded); they don't
"just happen" as many people think. It can be said that accidents are
the result of two immediate concerns: (1) the existence of substandard practices
and conditions and (2) ERRORS! Whenever substandard acts or conditions are
allowed to exist, the door is open to an incident in which the result is left
largely to chance. The result can be minor, serious, major or catastrophic loss.
The basic causes of accidents fall under two categories:
1. Personal Factors
A. Lack of knowledge or skill
B. Improper motivation
C. Physical or emotional problems
2. Job Factors
A. Inadequate job standards or training
B. Inadequate design or maintenance
C. Poor working conditions
D. Equipment or tool deterioration due to aging and normal wear
E. Abusive or abnormal use of equipment and tools
Accident prevention is everyone's responsibility. Every human being has a
primary responsibility to use his only tool of survival: his mind. We have
volition to choose to think or to default into laziness and not think. When we
choose to think, we are then capable of identifying reality and exercising
control over our environment and actions. Accident prevention requires control
over the causes of accidents. We must set standards (or adopt those already
existing), identify problem areas, train and educate fellow workers, set
standards and emphasize awareness as well as conformity to those standards.
There is no trying. There is only doing or not doing when it comes to accident
prevention.
1988 can be accident free for the fireworks trade if we all take the
necessary steps to do what is necessary for accident prevention. WO
"UNAVOIDABLE" ACCIDENTS
Here's a story for you that reads like a novel. It's the story of an event
that really occurred in a large industrial plant.
A man removed a guard from a machine to do some oiling. The oil can he was
using had a long spout for getting into the more remote parts of the machine.
While he was oiling the machine, the guard he had removed fell over, struck the
oil can and catapulted the spout so that it cut an ugly gash across the man's
right eyebrow, just missing the eye itself. A little later this man was in the
emergency ward receiving attention for the cut. He spoke about the accident to
the nurse who was attending him. "You know", he said, "that was
an unavoidable accident;! You can talk safety as much as you please, but there
are always unavoidable accidents and this was one of them."
Then the nurse asked, "Do you mean that you are going to let that same
thing happen to you again?"
"No," answered the man, "it will never happen to me
again."
"But how will you avoid it?" continued the nurse.
"By laying the guard in another position," answered the man.
So this man, who began by proclaiming this to be an unavoidable accident,
concluded by explaining just how it might be avoided. And he, by the way, was
considered a very intelligent man by his fellow workers.
There are two things we can say on this subject of "unavoidable"
accidents: (1) Accidents for which we are to blame, we tend to blame on others
or proclaim them as "unavoidable", and (2) scientific studies reveal
that 90% of the so called unavoidable accidents are really preventable.
Accidents don't "just happen." Good housekeeping, careful habits,
proper design and adequate safety training will decrease the number of so-called
"unavoidable" accidents, especially in the fireworks trade where the
consequences are so severe. There is a statement which I wish we might all keep
in mind: "Accidents are someone's fault don't let one be yours!" If we
all motivate ourselves to learn and practice safety if we avoid being lazy and
take that extra step to do what's right to assure safety, it should save us and
our loved ones much suffering.
When we work with fireworks, we must constantly be on guard against
complacency. Because we work with certain chemicals and do certain operations
all the time without incident, does not assure us an accident can't or won't
happen. All it takes is a source of energy, a minute spark to create a disaster
given the right conditions. And those conditions are the ones we must avoid as
well as the source of energy;! Remember, that extra effort to promote safety or
prevent accidents is cheap insurance indeed. - WO
FACTORY SAFETY: OSHA & THE COURTS
No malicious intent is needed to constitute a "willful" violation
of OSHA standards, according to a ruling of the Fifth Circuit Court of Appeals.
The court further declared: "Intentional disregard of or plain indifference
to the OSHA rules makes it a willful violation. A common sense safety policy
that leaves judgment up to the workers is insufficient." The case involved
a company that warned a crew to avoid overhead power lines, but did not tell
workers exactly how far they must stay away from the lines under OSHA standards.
A worker was electrocuted when a steel pole he was maneuvering touched a power
line. The company was fined $7,150.
In another case, the claim that an employee exhibited "idiosyncratic
behavior" was ruled no defense against an OSHA citation. This case involved
a steel plate in a shipyard that fell onto and killed a worker as it was being
welded. Necessary supports were removed. The company said it was employee error
that caused the accident, but the Occupational Safety and Health Review
Commission found that a better worker training program would have prevented the
"idiosyncratic behavior." An appeals court upheld the commission.
So how does this affect the fireworks industry? It is true that better than
60% of the fireworks businesses employ 10 or less people. This means that OSHA
will not target those businesses for periodic inspections. However, they are
mandated to inspect whenever they receive a complaint on that business, or if
there is ever an accident involving serious injury or a fatality.
When serious injuries and fatalities occur, one of the first questions that
OSHA officials will ask is, "Was the employee trained?" and,
"What records do you have of the training;?" The philosophy involved
in the OSHA law says in effect, "If a worker is exposed to a hazard, he
must be trained so that he is aware of what the hazard is and how to avoid
it." Employers must be aware of the hazards inherent to the nature of the
work and must make sure everyone understands what those hazards are. He must
know and train his people in the correct procedure, rules and regulations to
follow, in order to avoid an accident. Further, workers must know what to do if
a dangerous situation suddenly arises and be familiar with emergency procedures
to follow in order to avoid injury to themselves and others. Where potentially
dangerous work is involved, some companies write "shop order
procedures" (SOP) which is a training document detailing the routine for
each job. The SOP lists conditions, equipment to be worn or used, hazards to
avoid and details tasks step by step. Upon training, the employee is given a
copy of the SOP and signs a document attesting he was given and has read the
SOP. The courts hold, it is the burden of the employer to provide and maintain
safety for the employees.
This thinking is basic to the law. It covers all recognized hazards. There
must be training, and hand in hand with training must be proof: procedures,
training records, records of instruction or documented evidence of some sort
that says the worker was told and shown how to do the job right. The philosophy
of training in the OSHA law doesn't stop there. They go further and say that it
is the employer's responsibility to see to it that the employee follows
instructions and protects himself from hazards. If the employee is not properly
supervised and the worker is injured because he didn't wear safety protective
equipment, for example, the law places the blame on the employer, not the
employee.
The argument that a man was told about the hazard and was told to wear his
safety equipment, but failed to follow instructions, doesn't hold water. The
attitude of the OSHA Administration (supported by the courts) is that,
"Management must Manage." It is then management's responsibility to
take the steps necessary to assure that the man follows procedures and uses the
protection provided for him in the work place. One more thing to think about.
When OSHA charges and the courts find that an employer was willfully negligent
by not managing, training or removing known hazards ( for example, more than 10
lbs. of flash;) from the work shop an employer becomes wide open for civil
lawsuits regardless of the workers compensation rules. The worker's compensation
law is designed to protect employers from employee law suits in the event of
employee injury provided the injury was not willful. - WO
MORE ON ELECTRIC SQUIBS
It was previously mentioned (Aug '84 AFN, Safety Fax) the primer spot on
electric squibs are friction sensitive and should be regarded with care and
caution handling. Although the primer spot is somewhat desensitized by a
nitrocellulose lacquer coating, it can still be set off by rough handling such
as yanking from a quickmatch shell leader. It should also seem reasonably
logical to avoid setting heavy boxes down on top of squibs that may be laying on
a table top or to avoid stepping on squibs that may have dropped to the shop
floor. The squib itself is relatively harmless, but should be respected as a
serious source of ignition to other nearby material.
Electric squibs are in essence electric match heads. They are similar or
identical in construction to components of electric blasting caps and have
identical electrical characteristics. Squibs should, therefore, be regarded with
the same respect as electric blasting caps. They should be kept shunted at all
times (bare ends of lead wires twisted together). The shunt is an important
safety precaution. It prevents stray electrical current, either by induction or
by conduction, from setting off the squib. The shunt must not be removed until
field wiring interconnection. At that time, it is a good practice to have the
cabling shunted at the control firing box end, while connections are made at the
mortars and until just before the display begins. A specially wired shunting
connector could easily accomplish this, with the operator transferring the cable
connector to the firing panel output connector of the box a few minutes prior to
starting the display. (This presumes, of course, circuit debugging was
accomplished earlier in the day). Control panel designers should give this
safety feature serious consideration.
Electric squibs should never be stored in a magazine with other stocks of
fireworks or explosives. They should be kept separate and stored in a portable
steel box type magazine. It is possible for a nearby lightning strike to set-off
squibs via electromagnetic interference (EMI) and it has been known to happen on
rare occasions even with a good shunt in place. EMI is also a hazard in the
field and another good reason for shunting cables at the control box during
set-up and while waiting before the start of a display. Long lead wires and
cables act as antennae for absorbing EMI and radio frequency energy.
Multi-conductor cables used in field wiring should be the twisted pair type with
full shielding.
When hooking up squib wires, it is important to keep bare wire connections
from touching the ground, especially if the ground is damp. Tape over
connections or support them so no electrical contact is made with earth ground.
The reason is stray electrical currents flow within the earth's ground. Sources
of stray current can be utility pole transformer grounds (ground loop currents
between poles) or the ground plane of a nearby radio broadcasting station
transmitting antenna. Nearby high tension towers humming at 500,000 volts can
induce stray current into the ground or your antenna-like field cables. A
thunderstorm several miles away can cause stray ground current surges in your
area as lightning strikes the ground and finds paths through underground mineral
deposits, the water table or underground stream or aquifers. As little as 150
milliamps (.150 amps or 150/1000 amps passing through the resistive bridge wire
(heating element) of the squib can set it off. A standard 1-1/2 volt D cell
flashlight battery can deliver 4,000 milliamps or 4 full amps and an alkaline D
cell can deliver twice as much again. It has been recorded that lightning bolts
can deliver 100,000 full amps at a million volts in a single bolt! Given the
right conditions, a distant thunder storm that you may not even see or hear can
deliver stray ground current to your bare squib connections touching the ground.
The likelihood of the squib being in the path of a stray current is extremely
remote. However, these are the conditions that are reported to have caused
disasters with similar electric blasting caps over many years of experience by
blasting engineers.
It should be understood that voltage is the electrical "pressure"
that causes electrical current or amps to flow in a circuit. Current flowing
through a resistance creates heat which dissipates energy. The more current
flowing , the more heat energy and the quicker it is generated. The most common
way to increase current flow where resistance is fixed, (squib bridge wire plus
length of circuit wire) is to raise the voltage at the electrical power source.
This is the basic principle of the squibs ignition element current flowing
through a resistive wire finer than a human hair to create heat and ignite a
primer spot which produces a flame.
With more and more electrical firing of display fireworks taking place each
year, the operators must recognize and practice a new set of safety guidelines.
Without forming new electrical safety habit awareness or by taking squib safety
for granted, accidents will occur given the right conditions. Many will agree,
including myself, that electrical display firing is far less hazardous than hand
firing. Yet we must be aware of and respect the subtle dangers lurking in the
shadows of ignorance and avoid complacency in order to seek out and enjoy safety
perfection. - WO
UPDATE ON ELECTRIC SQUIBS
Extensive studies on electrical bridge wires for explosives initiation have
been undertaken for may years at the Franklin Institute and at companies such as
Atlas Explosives, Dupont and Ireco, Inc. where this writer is employed as a
staff Electrical Engineer. Resistive bridge wires of varying length, diameter,
alloy and hence resistive and thermal value are used in virtually thousands of
devices of differing design. Devices such as: squibs (a catch-all broad and
vague term in the industry), igniters, explosive bolts, detonators of many
different sizes and shapes, safe & arm military devices and blasting caps
are to name but a few. Electric igniters (or squibs as we fireworks people call
them) are electrically very similar to the electric circuit in blasting caps. In
fact, the ICI squib so commonly used by professional display operators, is the
exact same igniter manufactured and used in Atlas blasting caps. (Atlas is a
division of Gulf Explosives, Inc.). The electrical studies made on bridge wire
initiated devices involve, for example, environmental studies of performance
under extreme conditions. These tests include, but are not limited to, freezing,
baking, pressurized submergence in salt water, mechanical shock and vibration to
many g's, static electricity discharges, and RF energy excitation of finished
devices. Parameter measurements include studies for changes in: bridge wire
resistance, elapsed time from electrical initiation to detonation, fusion time
(initiation to bridge wire melt-down time), initiation energy requirements
(all-fire and no-fire current limits), explosive power output of the device, and
high voltage static electricity sensitivity.
The all-fire and no-fire current limits, RF energy excitation effects and
static electricity effects on fireworks squibs at ambient environmental
conditions is easily recognized as a safety concern. The all-fire current is
defined as the level of applied current at which 100% ignition is guaranteed by
the manufacturer. Generally, this figure is 1.0 amps flowing through the bridge
wire after allowing for wire line losses. The no-fire current limit is somewhat
more complicated and vague as environmental conditions have a great effect on
the value. Conditions such as temperature, ground leakage current , RF energy
excitation, the presence of static charges, etc. adversely affect the value of
this limit. However, no-fire current limit is generally defined as the minimum
applied current at which a squib is guaranteed to not fire under lab conditions.
This value is generally given at 0.1 amps (100 milliamps). For field circuit
testing, the Institute of Makers of Explosives (IME) recommends the test current
for measuring the resistance of field wiring by the user be limited to under
0.01 amps (10 milliamps).
Beware of the output test current of your ohm meter. Some meters, such as the
Simpson Model 260 Volt-Ohmmeter (VOM) can output as high as 200 milliamps of
test current on the ohms X1 scale (range). To test the output of your meter, set
the meter up to read ohms and measure the current with a second meter set-up to
read current. Read the test leads of the first meter directly with the test
leads of the second meter. Check each of the ohms multiplier scales by switching
the range selector switch on the first meter.
For more detailed information on the application of firing display fireworks
with electrical squibs, I recommend readers absorb the past and on-going fine
articles written by Sam Bases for AFN. (Incidentally, I have examined Sam's
panels up close and they are truly a work of art!) - WO
THE RESPONSIBILITY OF CHOICE
We have all heard or read about safety abuse issues having their root cause
in such things as: risk management, or risk analysis, or poor attitudes, or
statistical observations of so many near misses equal an incident, and so many
near incidents equal an accident. All of these observations are interesting to
think about and yet are open ended without integration into the reality of human
behavior. They don't really explain WHY accidents happen and continue to happen
despite all we learn or know! A search for the root reason brings us to an
understanding of the nature of choice.
Choice and the responsibility that comes with making choices allows us to act
for our survival or for our destruction. Plants and the lower conscious animals
can act only for their survival. Their behavior in the quest for nutrition and
other survival needs is automatic. They cannot form concepts or think in
concepts and therefore are not aware of their own self concept. They have no
ego. Man has no automatic survival behavior. He does have a concept forming
conscious mind with an ego. He must use his mind to act for his survival by
identifying what is good for him or what is bad for him. He has choices and can
also choose to act for his own destruction. To be successful at surviving, he
must exercise thinking effort to raise his consciousness and predict the outcome
of his choices. He is free to make any choice but he is not free to escape the
consequences of the wrong choice. Their are several ways he can fail.
If he chooses to suspend his conscious thinking before he acts, he will make
mistakes. If he acts on his emotions or feelings instead of his conscious
thinking, he will make mistakes. If he chooses to be lazy and not do his
"homework", i.e. read instructions, read labels, review safety rules,
etc., he will make mistakes. If he chooses to evade reality to satisfy a whim or
want, he will make mistakes. If he represses his mind to suspend his thoughts
because those thoughts may invoke fear, he will make mistakes. Notice how in all
these observations, a choice was involved. The choice to think or not think.
I have often wondered why the vast majority of humans spend their entire
lives evading the responsibility that comes with choice. A fundamental conflict
within each of us seems to be involved. Our self concept demands that we be
productive to be happy. We enjoy our achievements and knowledge at living
competently. Pride in our achievements is a virtue. However, we sometimes do
take chances when we suspend our conscious thinking efforts before we act. If we
make a serious mistake, we evade the responsibility and often fail to learn. We
are afraid of rejection, ridicule, emotional pain or punishment. Much of this
fear is a product of our childhood where we learned to evade truth for fear of
pain and punishment. The reality we experienced was a successful avoidance of
pain when we deceived the authority figures and the perceived threat. We learned
to avoid truth and equated it with surviving successfully. We were often
punished for telling the truth, which was always stated with innocence, then
fear. All of us have experienced this to one degree or another. We should have
been patiently taught to think, which is the root of responsibility. Instead, we
were taught rule following obedience, which is the root of a habit-forming
suspending of one's consciousness and looking to outside authorities to do our
thinking for us. The reality of this is no matter how many rules we memorize, we
will not be able to memorize a rule to solve every problem life presents us
with, nor remember it in the immediacy of an action demanding situation. At best
in this circumstance, we could only act on a feeling and most often it results
in a mistake.
There is no substitute for conscious thinking effort, and no one can do our
thinking for us. It is our nature that we have choices and can act for our
survival or destruction. Our only tool of survival is our mind. We have choices,
and must exercise thinking effort to be able to make the correct choices for
successful survival, and to live competently. Accidents involving human effort
and actions are the result of one's failure to think consciously and predict the
outcome of his actions. To be safe means to be conscious with focused awareness.
- WO
THE BEAUTIFUL 4" SPIDER WEB SHELL
One of the most spectacular, yet simple to make fireworks bombshell, is the
Spider Web. It is also one of the most inexpensive shells. Some companies call
this shell an Octopus, but the effect is the same. This shell packs a dramatic
punch when it bursts. Exploding with a bang, it instantly fills the sky with
golden tentacles spreading radially in straight lines and in all directions from
the center. The gold stripes are formed from the burning powdered charcoal trail
left behind as the stars are hurled at high speed. The pattern just hangs in the
sky for many seconds before fading. A four inch canister Spider Web shell, when
made properly, looks like a six inch chrysanthemum. Fire 5 of these in a salvo
or flight and an awesome checkerboard spider web fills the sky! Here's how I
have refined the Spider Web to perform better than any others I have ever seen:
Stars are cut 5/8" or 3/4" (large) square. The formulae:
FORMULA 1 FORMULA 2
Commercial Meal D 10.0 Lbs.
Potassium Nitrate 7.5 15.0 Lbs.
Air Float Charcoal 7.5 9.0
Sulfur 1.0 2.0
Dextrin 2.0 2.0
While the formulae are given in Lbs., smaller batches can be made by
substituting grams, ounces, etc. for the Lbs. or by multiplying or dividing all
the quantities by the same number, keeping ratio relationships the same. For
example, Formula 1 can be weighed out in ounces with each quantity multiplied by
two to make enough stars for 3 or 4 shells. Formula 1 is a very fast burning
star because it is 50% commercial Meal D black powder. It will ignite 100% from
the strongest flash bag. The stronger, the better! Formula 2 needs to be ball
milled for at least ten hours to be almost as fast, yet just as ignitable as
formula 1. Because it burns slightly slower than formula 1 (after ball
milling;), these stars achieve a larger spread in the sky. Ball milling also
serves another purpose. It reduces the amount of ash and shortens the charcoal
glow time. Without ball milling, some of the sparks may glow all the way to the
ground. With ball milling, the golden stripes are more uniform and more
beautiful, fading in unison. Formula 1 (less the Meal D;) can also be ball
milled to achieve uniformity and less ash. Add the Meal D after ball milling the
rest of the chemicals. Very slight dampening with a volume mix of 80% water with
20% denatured alcohol is helpful during ball milling. By slight I mean just
enough to settle the dust but the mass still feels dry and flows freely as a
powder.
Commercial quantities can be ball milled in an electric cement mixer that has
been modified. I did this by removing the blades and reinstalling the bolts to
prevent leakage of powder out of the bolt holes. I also removed the motor and
replaced it with a totally enclosed (sealed) motor, and thoroughly electrically
grounded the machine. Ball milling of a mixer charge of 28 Lbs. of Spider Web
mix, was done with a set of inexpensive Bocce Balls! The mouth of the mixer was
sealed with a sheet of heavy plastic cut in a circle larger than the opening of
the mixer vessel. The plastic cover was held in place with bungee cords. After
10 hours, the powder was absolutely beautiful and performed exquisitely after
the stars were made.
If one tries to burn the star composition after mixing and ball milling, one
will be disappointed. It appears to be smoldering and slow as if something were
done wrong. This is normal. After the stars are made by thoroughly dampening
with water, forming loafs in a frame, slicing, dicing, dusting and drying the
stars perform quite differently! Burn time for a 3/4" star is less than 1
second. The star is very sensitive to low temperature incandescent heat
ignition, yet is very stable and insensitive to friction or impact. This makes
the star ideal for hard breaking flash bag bursts!
Once the stars are made, I use the following materials to assemble a 4"
Spider Web Shell;:
*Paper Can with end caps 3-1/2" dia. X 4" long
*3 Chipboard discs, 1/8" thick X 3-1/2" dia.
*Jap 1/4" Time Fuse, 3 seconds between cross match
*Dime size Coin Wrapper for making Flash Bag
*Wooden Dowel, 5/8" X 4" for making Flash Bag
*Masking Tape
*Spool of 12 ply Cotton Twine or equal shell twine
*Enough good Flash Powder to fill a dime wrapper
*Igniter Cord for cross matching time fuse
*Elmer's White Glue and/or Hot Melt Glue & gun
*Pulverone or home made granulated black powder
*Wallpaper wheat paste
*Kraft Paper, 70 Lb. and 20 or 30 Lb grades
*Quickmatch fuse
*FFA Black Powder for Lift Charge, 2 Oz.
The shells can be made the traditional way of rolling a paper casing but my
way (with paper cans;) is easier to assemble and performs equally as well. Two
of the chipboard end discs should have center holes to receive the 1/4" Jap
time delay fuse. With Elmer's white glue, I fasten a disc inside the loose end
cap of the paper can (the can bottom end cap should already be glued in place).
A weight is then placed on this disc and set aside to dry. Next, I slide the
dowel inside the dime size coin wrapper almost the full length of the wrapper. I
then crimp the end of the wrapper over the end of the dowel to close off the
dime wrapper forming a bottom. A short piece of masking tape is then placed over
this crimped end to seal the bottom of this soon to be flash bag. Using a hot
salute flash powder, I fill the flash bag 3/4 full. Next, the time delay fuse,
cut to the correct length and cross matched with igniter cord, is inserted (with
cross match) into the flash bag. The bag is gathered around the time fuse and
tied with twine just above the cross match.
Being sure to center the flash bag among the stars, I next load the stars and
flash bag into the paper can. The spaces between the stars can be filled in with
pulverone or granulated homemade black powder. The pulverone filler is necessary
with hand rolled casings but optional if using a paper can. This type of shell
functions equally well without pulverone. The top edge of the flash bag where it
is gathered around the time fuse must be kept even with the top edge of the
paper can. Next, I smear a generous portion of Elmer's white glue around the
inside circumference of the paper can end cap that was previously set aside.
Holding the time fuse centered, I lower the paper can end cap with chipboard
disc (glued inside cap) onto the fuse and paper can. Once the end cap is seated
onto the paper can and while applying hand pressure to keep the cap from
springing back up, I apply masking tape around the circumference of the cap
where it meets the can wall. The bottom end cap of the paper can is also taped
and sealed.
I next gently pull up on the time delay fuse to assure the top of the flash
bag is against the inside disc. A generous portion of Elmer's glue is smeared on
the outside of the top end cap and around the time fuse to seal against lift
flame entry. I then assemble another chipboard disc with center hole over the
fuse and down against the paper can end cap. This disc is taped down in four
locations 90 degrees apart to hold it in place while the glue dries. The third
solid chipboard disc is glued to the bottom of the shell in an identical manner.
Next, I glue a generous fillet of Elmer's around the time delay fuse to complete
the double seal against lift flame. The shell is now set aside for the glue to
dry overnight.
The next step is spiking the shell with twine. Two parallel lines of twine
are applied simultaneously to give a strong hard break and symmetrical star
pattern.
I start by looping the free end of the twine around the time fuse, holding
the end down, as twine is fed out and laid down against the shell wall, crossing
over the top of the free end. The spiking pattern follows the sketch in Fig.2,
and is tied off with a clove hitch knot around the entire circumference of the
shell, after spiraling up the side. Running cotton twine through a wheat paste
slurry and wiping off the excess as it is applied to the shell, will greatly
enhance the strength of the spiking.
After spiking, the shell is ready for pasting. Kraft paper (70 Lb. rating) is
cut so the paper grain will lie parallel to the shell length. The width of the
paper is cut so that it will cover the full length of the shell, and fold over
to cover 2/3 the diameter of the shell at each end. The length of the paper
should be 48 inches. Each shell gets pasted with a sheet this size. A slurry of
wheat paste is prepared and generously brushed on both sides of the paper. The
paper must be thoroughly soaked. The paper is folded like a bellows and squeezed
with the hands to make the paste penetrate the fibers of the paper and to soften
the paper. I then smooth out the paper on a formica table top and roll the shell
tightly, centering the shell in the paper while working out any air bubbles. The
paper that extends over the ends of the shell is torn in strips about an inch
wide. The tear is made from the end of the paper to the end of the shell. These
strips are laid down over the end of the shell and smoothed tight against the
spiking, working out air bubbles. On the fuse end, I keep all the strips on the
same side of the fuse as I rotate the shell laying down each strip. I make sure
there is a good tight seal around the time delay fuse. When finished, the shell
is set aside to dry in the air stream of a fan or out in the sun.
The shell can be finished as any shell. The final cross match hole is punched
in the fuse and a piece of igniter cord is inserted. I have also split and
primed the time fuse with nitrocellulose lacquer and black powder when out of
igniter cord (igniter cord can be purchased from Coonie's Explosives, Hobbs,
NM). Some shell makers finish the shell with the time fuse up and a pass fire
quickmatch connecting the top of the shell with the lift powder at the bottom.
The quickmatch long fuse is introduced to the top of the shell where the time
fuse and pass fire are connected. I prefer to invert the shell putting the time
delay fuse directly into the lift powder. However, I wouldn't do this if I were
using a spoolette time fuse. Spoolette fused shells have to be fired fuse end up
or the spoolette core will blow through on lift.
For final assembly, I roll the shell with a quickmatch long fuse, in 3 turns
of 20 or 30 Lb. dry kraft paper. The long fuse lays parallel to the shell. The
paper should be wide enough to cover the length of the shell plus cover the full
diameter of each end of the shell. The end of the quickmatch has the paper
trimmed back 3/4" exposing the black match. This end is bent over the end
of the shell where the lift charge will be introduced. Two ounces of FFA
commercial black powder is poured into this end of the shell covering the bare
end of the quickmatch and surrounding the time delay fuse. The paper, starting
with the inside rolled layer, is laid down over the black powder. The final turn
of paper is gathered and tied off. I then trim off any excess paper beyond the
clove hitch knot. The final touch is to install a mopoline or safety cover on
the end of the long fuse to be ignited. The long fuse is then folded and secured
with a rubber band and labels placed on the shell. - WO
REDUCING THE CHANCES OF ACCIDENTS
No where is the potential for accident more real than in the operations of
making fireworks. I have heard comments ranging from, "it just
happens," to "all accidents are preventable." I'm not a fatalist
and do not subscribe to the idea that, "accidents just happen." The
fact is that accidents are preventable. This fact gives us the incentive to
avoid the known hazards. It also gives us the incentive to identify the unknown
hazards during experimental research and to investigate the probable cause
hazard after an accident. If you believe "accidents just happen," then
you have a limited future in fireworks.
The hazards of fireworks can be placed in four categories:
1. Accidental ignition due to spontaneous combustion.
2. Accidental ignition due to static electricity.
3. Accidental ignition due to human carelessness.
4. Poisoning due to mishandling of toxic chemicals
In the first category, ignition due to spontaneous combustion, the accident
usually occurs from mixing chemicals that are incompatible, especially in a wet
state such as in making stars. Sometimes the reaction can be subtle (without
ignition;) and go unnoticed until the stars have dried. Then the mixture may be
unstable and extremely sensitive to friction or be so hygroscopic that it
becomes wet again on a future humid day. Combining ammonium perchlorate and
potassium nitrate yields this reaction. Stars that are hygroscopic can also
become wet again inside a shell that has recently been pasted. A wet star
containing sulfur could spell out spontaneous disaster when assembled with a
potassium or barium chlorate star. Leaving wet star composition laying around
(in bulk), especially if they contain any metal powders, is an invitation to
spontaneous combustion. Acids or alkalinity can form to attack and corrode the
metal powder creating heat. The increased temperature aids the reaction by
stimulating more electron activity to form stronger acids or alkalinity, which
further increase the heat. The water begins to vaporize and the heat continues
to build until there is not enough water to prevent combustion. Toxic gases can
be released during the heat;-up stage making the air dangerous to breathe. Some
reactions are slow taking days, weeks or months and no combustion occurs due to
the low level of heat generation. Yet the products of reaction can be hazardous
or render the intended mix useless as a fireworks item.
In the second category, accidental ignition due to static electricity, we can
also include electric sparks from other sources such as light switches, motors,
etc. If fireworks powders are to be mixed indoors, a tremendous amount of
electrical engineering and special fixtures are necessary for assurance against
ignition of airborne dust due to electrical spark. Explosion proof conduit,
lighting and outlet fixtures, and junction boxes are also very costly. The
easiest way to avoid that cost is to simply mix powders outdoors. A pole barn or
gazebo structure overcomes the problem of rain, and the electrical hazards to
air born dust are isolated.
Static electricity is a problem all of its own, and controlling it is more
difficult simply because we never know when it is going to occur. We can,
however, take steps to reduce its hazard.
Workers should wear only cotton clothing and this includes socks and
undergarments. The work room floor and tables should be conductive and earth
grounded through a 100 thousand ohm resistor. The resistor allows the static
charges to "bleed off" and prevents a sparking arc. The resistor
should be in series with the ground source. Workers should also wear special
conductive shoes which, if worn daily, should be discarded for a new pair at
least once a year. Conductive shoes can be obtained through most popular shoe
stores, or orthopedic specialty shoe stores. Chemical mixing, especially with
metal powders, should be done on days when the relative humidity is 65% or
better and during the warmer seasons. When the air is warm, it holds much more
water for a given percentage of relative humidity than for the same percentage
when cold. Humid air reduces the chance of an arcing static spark because the
charges bleed off at lower voltage levels than necessary for an arc to occur. If
mixing is done indoors, the work room should be climate controlled for 65%
relative humidity at 70 degrees F, +/- 10%. Avoid using plastic containers for
mixing, measuring, or storing. Solidly ground all electrical equipment and
machinery.
In the third category, human carelessness is where most fireworks accidents
can be attributed. "The responsible person knew better, but took a chance
anyway," or "he just didn't know any better." The number one rule
everyone making fireworks should adopt is: "If you don't know, you don't
do!" At least until you know all the facts about what it is you intend to
do. I firmly believe one of the biggest contributing factors for this industry's
poor safety record (in the U. S. A.) is the prevalent attitude of prideful
secrecy among professionals, and the ignorant curiosity of man. Don't do unless
you know. For example: you have just mixed a 5 ounce batch of a new formula
using chemicals you know nothing about. The formula works. Should you go ahead
with making a 20 pound batch? Have you done friction sensitivity tests? Impact
tests? Chemical compatibility research? Toxicity research? Or have you only
decided a 5 ounce sample worked good when ignited? A lot of unknown hazards
could exist that are difficult or impossible to control or need special handling
consideration in larger batches, especially when wet mixing for stars.
Familiarity breeds contempt. The fire worker should remind himself of this
daily. We are all prone to fall into the trap. When a particular operation has
been accident, or incident free for many years, it doesn't mean an accident
can't ever happen. If we let our guard down, or take short cuts and chances, an
accident will happen.
Mother nature (physics and chemistry) has set the rules that we must identify
and abide by if we are to play with her toys. In fireworks, you can't fool
nature and get away with it. It makes no difference who you are, how much money
you have, or how much knowledge you possess no man is forgiven for breaking the
rules. It takes self discipline to be careful, and being careful is cheap
insurance. One who scoffs at safety rules is truly a fool.
Poisoning due to mishandling chemicals seems to be the least concern of most
pyros, as so little has been written on the subject. Fires and explosions make
spectacular news reports, and the thought of being involved is certainly
terrifying. Yet death by poisoning is the same as death by fire, and can be
equally agonizing for the victims and their families.
Have you ever mixed a batch of black powder, then blew your nose to find the
tissue paper full of black? What about the black that didn't come out? You can
be sure that some of it made it to your lungs. Finely powdered chemicals become
air born during mixing, and almost all fireworks chemicals are toxic to one
degree or another. They can enter your blood stream through your lungs, eyes,
ears, mouth, throat, stomach, under fingernails or in some cases are absorbed
through the skin. Symptoms of poisoning include any one of the following:
fatigue, headache, nausea, vomiting, dizziness, cramps, double vision, diarrhea,
nose bleeds, burning blood shot eyes, or skin rashes. Poisoning can be mild
(unnoticed) to severe (resulting in death). But I ask, what are the long term
effects to exposure? Know your chemicals! Most public libraries have chemical
dictionaries which spell out the toxic hazards. Ask suppliers for material
safety data sheets. Obtain and use quality safety equipment such as: dust
respirator, face shield or safety goggles, apron, and rubber gloves. Shower
after handling or mixing chemicals. Clean your fingernails which can trap nasty
little doses that will inevitably end up in your mouth, eyes, nose or other
personal body parts of yourself or other intimate loved one. Wash your clothes
twice and separate from the laundry of others. Again, this is cheap insurance.
I believe most, if not all people, love the spectacular beauty of fireworks.
Yet these same people are the first to ask: "You make fireworks? Isn't it
very dangerous? Are you nuts!??" It is we, all of us who make fireworks,
who have given this industry a black eye. Isn't it time to turn it around?
Safety is a constant and on-going state of consciousness. It doesn't exist
unless we make it exist, daily. All the aspects of safety and accident
prevention can not be stated in such a brief essay on the subject. If I have
made you think, than some good has been achieved. Always think safety first! -
WO
ABOUT THE AUTHOR
Bill Ofca began his technical education in the United States Air Force, from
1966 to 1970, where he completed fifteen different technical courses in
electronics. He graduated the USAF 3380th Technical School with honors. Bill was
stationed from 1967 to 1970, with the 76th Aerospace Rescue and Recovery
Squadron in the Pacific, in direct support of splash down recovery for the
Apollo space missions to the moon.
From 1967 to 1970, Bill attended night classes at the University of Hawaii.
From 1970 to 1973, he attended classes at the State University of New York and
the University of Connecticut.
Bill was employed by the Alpha Laval Co. for ten years in progressive
positions including: Factory Service Engineer, Assistant Manager of Quality
Control, Electrical Control Design Engineer, Field Engineering Supervisor of
Fuel Treatment Systems Group, Process Control Engineer, and Chemical Process
Engineer of Mineral Oils Division. During this time, Bill gained valuable
experience designing explosion proof systems and controls. Extensive
international travel for field commissioning of systems was a major part of
Bill's experience.
For the past eleven years, Bill has been employed by IRECO, Inc., one of the
largest explosives and detonator manufacturers in the world, and the largest in
the United States. His position at IRECO is Electrical Engineer, and Supervisor
of the Electronics Lab.
From 1980 to 1990, Bill was co-owner and chief executive officer of the
Legion Fireworks Co., Inc. of Wappingers Falls, New York. He has extensive
knowledge and experience in the design, manufacture, and display of exhibition
fireworks. His credits are many and include designing and operating very large,
electrically fired, FM radio music simulcast displays. He has lectured at
business seminars, and trained many professional display operators to shoot
displays.
For the past nine years, Bill has been writing "Safety Fax" and
"Pro Fax" feature articles for American Fireworks News, and has
occasionally written articles for Fireworks Business News.
In 1988, Pyrotechnicians International, Inc., a large mid-western
organization of fireworks businesses, recognized Bill's contribution to
fireworks safety by awarding him the PI Safety Award for that year.
Bill is married, with two grown boys, and lives in Hyde Park, New York.
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