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There were two naughty little boys in the street. One was playing with battery acid, the other boy was eating the contents of a blackpowder rocket.
A member of the public reported them to the police, who promptly arrived, chained them, and dragged them down to the local station.
The cops charged one of the boys. What happened to the other? They let him off!
How do you make a cat go 'woof'?
Pour petrol over it and light!
What happened to the dumb terrorist who tried to blow up a bus?
He burnt his lips on the exhaust!
Did you hear about the dyslexic pimp?
He bought a warehouse.
What have Arsenal and a 3-pin electrical plug got in common?
They're both useless in Europe.
A man walks into a bar with a steering wheel in his underpants.
The barman asks: "Is that painful"?
The man replies: "It's drving me nuts!"
What's the biggest drawback in the circus?
An elephant's foreskin.
Scotland Yard are having a crackdown on Viagra smugglers.
Police are reported to be looking for 20 hardened criminals.
Quasimodo, the Hunchback of Notre Dame, returns home from a hard day ringing the cathedral bells-and finds his girlfriend standing in the kitchen with a wok.
"Fantastic", he says,"Is it Chinese tonight, Esmerelda?"
"Oh, no," she says, "I'm ironing your shirt."
Topics I've Started
Lampare
28 April 2008 - 03:08 PM
I intend to construct an aerial fireball effect, known among the pyrotechnics community as a lampare.
I have decided to go one step further and add a small amount of boric acid to methanol fuel, to obtain a green fireball effect. The methaol reacts with the boric acid to form a borate ester, which is easily volatilised and burns with a green flame. However, I want to do this safely and without getting burnt!
So, I would appreciate some advice from fellow pyros.
How is the lampare ignited? Does the fuel need to be atomised into a fine spray before ignition?
I have decided to go one step further and add a small amount of boric acid to methanol fuel, to obtain a green fireball effect. The methaol reacts with the boric acid to form a borate ester, which is easily volatilised and burns with a green flame. However, I want to do this safely and without getting burnt!
So, I would appreciate some advice from fellow pyros.How is the lampare ignited? Does the fuel need to be atomised into a fine spray before ignition?
An interesting read...
23 April 2008 - 12:51 PM
Personal visible spectroscopy is key to the search for green fireworks, not only figuratively but from the literal position of searching for environment friendly bangs and flashes.
Humanity's pyrotechnic fascination began more than two millennia past when it was discovered that saltpetre, potassium nitrate, could accelerate explosively the combustion of organic matter. Civil and military applications from entertaining displays at Olympic opening ceremonies, to pyrotechnics for safety, airbags, fire extinguishers, flares, and the synthesis of nanoporous foams (for catalysis, hydrogen storage, and insulation) and propellants, are now almost ubiquitous. With such widespread use, however, comes the potential for environmental harm.
Pyrotechnics is a vast industry - $2.6 billion annually in pyrotechnics and explosives. Current pyrotechnics involve the use of toxic metals. However, less noxious organic alternatives that can provide the requisite explosion and illumination are keenly sought.
Now, Georg Steinhauser of the Vienna University of Technology, Austria, and Thomas Klapötke of the Ludwig-Maximilian University of Munich, Germany, discuss nitrogen-containing compounds - energetic materials, such as the derivatives of tetrazoles and tetrazines - that could displace heavy metals in pyrotechnic compositions. They have found that a complete range of explosive colours is possible with the ironic exception of green, which usually requires barium salts.
"No other application in the field of chemistry has such a positive association for the general population as fireworks," enthuses Klapötke, "However, pyrotechnic applications are significant polluters of the environment." Writing in the Wiley journal Angewandte Chemie, Klapötke and Steinhauser suggest that the development of unstable nitrogen-rich compounds and various other strategies could mitigate this problem.
Pyrotechnics require an oxidizer and a reducing agent and, depending on the application, a binding material, propellant charges, colouring agents and smoke- and sound-producing materials. This veritable chemical cocktail releases a whole slew of pollutants when deployed, releasing among other materials, lead, barium and chromium, chlorates, dioxins, smoke and particulates, carbon monoxide, and nitrogen and sulfur oxides. "For a long time, the consequences of this were not considered," adds Klapötke, "in the meantime scientists have been working on more environmentally friendly alternatives."
The main obstacle to making green pyrotechnics is cost. Any new product must compete on price with the established market. Klapötke, however, suggests that "Lawmakers and other promoters must intercede to address this."
The next generation pyrotechnics will exploit the high heats of formation of nitrogen-rich compounds rather than drawing energy from the conventional oxidation of a carbon backbone. Such metastable or unstable compounds release their energy of formation as they decompose explosively without producing smoke.
Interesting candidates for pyrotechnic alternatives include the tetrazoles and their derivatives, these compounds contain a five-membered rings composed of four nitrogen and one carbon atom, as well as tetrazines, six-membered rings made of four nitrogen and two carbon atoms. For example, salts of aminotetrazole salts can be formed with non-toxic metal ions, such as lithium, sodium, potassium, rubidium and caesium to make red, orange, violet, purple, and pink flames. Only green is missing from the pyrotechnic palette but researchers are looking for barium-free green-burning salts based on copper compounds.
One aspect of the fireworks clean-up that remains is avoiding perchlorate as the oxidiser and chlorine source because of its toxicity. "A possible solution to this problem could be the introduction of metal nanoparticles into the pores of nanostructured metal oxides," the researchers suggest. This remains an important challenge for chemists.
The new class of nitrogen-rich pyrotechnics offers not only environmentally friendly combustion products but the colours are often richer and more intense, say the researchers. Soon we could see smokeless, poison free and far less-polluting fireworks filling the ceremonial night skies, just as long as they are green.
Related links:
Article by David Bradley
Article on environmentally-friendly fireworks, taken from www.spectroscopyNOW.com
Humanity's pyrotechnic fascination began more than two millennia past when it was discovered that saltpetre, potassium nitrate, could accelerate explosively the combustion of organic matter. Civil and military applications from entertaining displays at Olympic opening ceremonies, to pyrotechnics for safety, airbags, fire extinguishers, flares, and the synthesis of nanoporous foams (for catalysis, hydrogen storage, and insulation) and propellants, are now almost ubiquitous. With such widespread use, however, comes the potential for environmental harm.
Pyrotechnics is a vast industry - $2.6 billion annually in pyrotechnics and explosives. Current pyrotechnics involve the use of toxic metals. However, less noxious organic alternatives that can provide the requisite explosion and illumination are keenly sought.
Now, Georg Steinhauser of the Vienna University of Technology, Austria, and Thomas Klapötke of the Ludwig-Maximilian University of Munich, Germany, discuss nitrogen-containing compounds - energetic materials, such as the derivatives of tetrazoles and tetrazines - that could displace heavy metals in pyrotechnic compositions. They have found that a complete range of explosive colours is possible with the ironic exception of green, which usually requires barium salts.
"No other application in the field of chemistry has such a positive association for the general population as fireworks," enthuses Klapötke, "However, pyrotechnic applications are significant polluters of the environment." Writing in the Wiley journal Angewandte Chemie, Klapötke and Steinhauser suggest that the development of unstable nitrogen-rich compounds and various other strategies could mitigate this problem.
Pyrotechnics require an oxidizer and a reducing agent and, depending on the application, a binding material, propellant charges, colouring agents and smoke- and sound-producing materials. This veritable chemical cocktail releases a whole slew of pollutants when deployed, releasing among other materials, lead, barium and chromium, chlorates, dioxins, smoke and particulates, carbon monoxide, and nitrogen and sulfur oxides. "For a long time, the consequences of this were not considered," adds Klapötke, "in the meantime scientists have been working on more environmentally friendly alternatives."
The main obstacle to making green pyrotechnics is cost. Any new product must compete on price with the established market. Klapötke, however, suggests that "Lawmakers and other promoters must intercede to address this."
The next generation pyrotechnics will exploit the high heats of formation of nitrogen-rich compounds rather than drawing energy from the conventional oxidation of a carbon backbone. Such metastable or unstable compounds release their energy of formation as they decompose explosively without producing smoke.
Interesting candidates for pyrotechnic alternatives include the tetrazoles and their derivatives, these compounds contain a five-membered rings composed of four nitrogen and one carbon atom, as well as tetrazines, six-membered rings made of four nitrogen and two carbon atoms. For example, salts of aminotetrazole salts can be formed with non-toxic metal ions, such as lithium, sodium, potassium, rubidium and caesium to make red, orange, violet, purple, and pink flames. Only green is missing from the pyrotechnic palette but researchers are looking for barium-free green-burning salts based on copper compounds.
One aspect of the fireworks clean-up that remains is avoiding perchlorate as the oxidiser and chlorine source because of its toxicity. "A possible solution to this problem could be the introduction of metal nanoparticles into the pores of nanostructured metal oxides," the researchers suggest. This remains an important challenge for chemists.
The new class of nitrogen-rich pyrotechnics offers not only environmentally friendly combustion products but the colours are often richer and more intense, say the researchers. Soon we could see smokeless, poison free and far less-polluting fireworks filling the ceremonial night skies, just as long as they are green.
Related links:
Article by David Bradley
Article on environmentally-friendly fireworks, taken from www.spectroscopyNOW.com
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Organic, green fireworks
