Flash Powder performance figures needed
#1
Posted 13 March 2012 - 05:30 PM
Composition make-up (% of fuel / %oxidiser )
Energy output per specified weight - for example x joules per gram
Mean temperature of the measurement
Source of the data
Thanks in advance.
#2
Posted 13 March 2012 - 06:14 PM
#3
Posted 13 March 2012 - 06:41 PM
Complicated stuff Perhaps a certain speaker at the AGM might be able to help, or may even be able to test some as part of a demo or something.
Thanks. I'll stick to text books.
#4
Posted 13 March 2012 - 08:08 PM
This may be worth a look , probably have to pay for the full article to find out though.
http://resources.met...6k&size=largest
#5
Posted 13 March 2012 - 08:25 PM
As someone who is decidedly not qualified to answer I'll give it a stab anyway.
Our starting point might be to assume a roughly stoichiometric mixture - say 64/36. The difference between the enthalpy of formation of our starting mixture compared with that of the reaction products should give some idea of the energy released per gram. This could be measured in the lab with a sealed underwater combustion chamber (bomb-calorimeter). The result however will be somewhat misleading as the reaction products from flash are essentially solids. The 'bang' seems to come from the vaporised particles and moisture that expand and promptly re-condense. We therefore have to think about the useful (coupled) energy released which, unlike conventional explosives is probably rather different.
As for reaction pressure and temperature, I guess we're back the good old PV=nkt regime from the physics classroom... Confine the volume, the pressure escalates, confine both and the temperature increases proportionally. Given that the stuff does self-confine we tend to get a bang. The temperature could be estimated via colour spectrometry to a reasonable degree but it's white hot, so pushing at least 4000 Kelvin.
If it does actually detonate of course (still hotly debated... technically I suspect not), then we're in to a different regime altogether...
Edited by BrightStar, 13 March 2012 - 08:28 PM.
#6
Posted 13 March 2012 - 09:42 PM
#7
Posted 14 March 2012 - 03:05 PM
I never saw a convincing answer, theories were anything from 4 to 1 to 20 to 1.
I had a good look and the above abstract was all i found.
Plenty of accidents in early photographic days but no real science, mostly Mg though.
Quote
" [14,15], but to the best of our knowlege nothing has been published
on the thermal behavior of AL+ Potassium chlorate."
It is possible that no-one has done the science you need.
I did wonder if power rather than energy would be a better measure as it takes into account detonation speed.
Best answer i saw was b**w something up and compare the size of the bits afterwards, well it made me chuckle anyway.
#8
Posted 14 March 2012 - 10:40 PM
These are American publication packed full of technical pyro content - well worth getting, they used to be put together by Ken and Bonnie Kosanke (highly regarded pyro chemists).
I know some Americans that run speed trials with flash compositions:
A long tray filled with composition with two pieces of fishing line spaced at 1 metre holding down micro switches, these trigger and stop a timer as each piece of fishing line is burned though. Apparently the fastest compositions are approaching detonation velocities!
Hope this helps.
Steve
#9
Posted 15 March 2012 - 06:25 AM
It might be worth consulting the Journal of Pyrotechnics, this information will probably be in one of the issues or their dirctionary of pyrotechnics publications.
These are American publication packed full of technical pyro content - well worth getting, they used to be put together by Ken and Bonnie Kosanke (highly regarded pyro chemists).
I know some Americans that run speed trials with flash compositions:
A long tray filled with composition with two pieces of fishing line spaced at 1 metre holding down micro switches, these trigger and stop a timer as each piece of fishing line is burned though. Apparently the fastest compositions are approaching detonation velocities!
Hope this helps.
Steve
Thanks Steve.
I think that my dilemma has been resolved thanks to some data extracts supplied by Helix.
Thanks to all who responded.
#10
Posted 15 March 2012 - 12:57 PM
#11
Posted 17 March 2012 - 06:30 PM
Thanks Trevor.Danny: IIRC, there were some studies done on the TNT equivalence of flash - I think it was in the Journal Of Pyrotechnics, though there's a figure listed on the NCTC site.
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