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impact sensivity?


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#1 thelawnmowermaninky

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Posted 03 August 2017 - 06:18 PM

absolute newbie here,  

 

have no experience with flash powder,  other than the fact that the more i read the more respect i have for it.

very willing to trade off bang for safety,  not into fireworks, interested in binary targets for rifles,

something sensitive to a 22lr vs a larger caliber, 

 

my question being,  would a less fine aluminum powder mixed at 70/30,

be safer than flake and more impact resistant,  

 

i've seen some what appears to me some very dangerous practices on you-tube,

as far as mixing, and handling, 

 

i do not want to become a member of the nine digit club...

 

thanks in advance for any insight on this......

 


#2 OldMarine

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Posted 03 August 2017 - 07:46 PM

There are umpteen threads on the subject here. Do some googling since it's a newb boomer subject that no one wants their name on. 


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Come on! Name one other hobby in which you cheer as your money and hard work go up in smoke!

#3 thelawnmowermaninky

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Posted 04 August 2017 - 07:16 PM

all i got by googling was conflicting information, i've been researching for 6 months now,

 

tried to do some real home work prior to winding up here, 

i've talked with several phd chemist, but they hod no experience with pryotechnics,

 

just want to approach this from the safest manner possible,

 

and i've read this topic and forum front to back,  

just could not seem to find certain specifics or maybe i'm not asking the correct question,

thanks.



#4 NeighborJ

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Posted 04 August 2017 - 08:02 PM

Friction and impact sensitivity is only one of many possible sources of ignition for Flash. The real danger of flash powder is it's tremendous release of energy and potential for destruction coupled with its high sensitivity to ANY source of ignition.

Using coarser aluminum will not decrease it's energy potential but will only lessen the likelihood of it performing properly, unless it is used with the correct application and construction. In short, choosing a flash formula has little to do with safety and more to do with purpose, cost, illumitation, and sound.

All flash compositions share the same dangers of ignition and will become violent if enough of it is ignited unconfined. Those amounts very from comp to comp, particle size and quality of chems.

The best advice I can give you is to find a local club and an experienced member who can help guide you thru all this, these forums can give you enough info to do what you want but they can't help you identify the hazards which you may not think to write about in a post.

Jason

Edited by NeighborJ, 04 August 2017 - 08:05 PM.


#5 OldMarine

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Posted 04 August 2017 - 08:21 PM

I've been in this hobby for going on 3 years and I've only recently felt comfortable enough in my knowledge and skill to make binary salutes for my rockets. I use whistle for burst enhancer and have no other use for high energy materials right now. 

I wish I could help but you're going down a road I haven't traveled but a foot or two.


Come on! Name one other hobby in which you cheer as your money and hard work go up in smoke!

#6 Richtee

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Posted 05 August 2017 - 03:35 AM

Have a read...  http://www.amateurpy...itizer-content/


I like smoke! On food or in the air equally well.

#7 NeighborJ

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Posted 05 August 2017 - 04:10 AM

Richtee, is your link for something in the HE section? I get an error message stating that I do not have permission to view that forum.

#8 thelawnmowermaninky

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Posted 05 August 2017 - 05:10 PM

thank you neighbor j....  et al. for your time and knowledge

 

it's the "dunning kruger effect"  the more i learn the more i know that i don't know.

 

and fully understand that just the air pressure is enough at 30 psi

to confine flash to release the same amount of energy.

 

here is some data i found concerning impact, friction, and energy ,

however the ratios seem out of sorts from what else i've studied?

 

 

 

  1. Analysis of Pyrotechnic Components 

  2. 5.5.1. Potassium chlorate and aluminum homemade flash powder

    This standard was made by mixing 1.38 grams of atomized aluminum powder with 0.62 grams of potassium chlorate. The two components were mixed by hand for approximately 10 minutes before being submitted to testing.

    Data Summary of KClO3 and Al standard: Mechanical Insult Data

    •   Impact (H50%) 71 cm

    •   Friction (F50%) 71 psi

    •   ESD (Joules) 0.013 J

      Primary Chemical Results

    •   Predominant metals (EDAX) Al, K, Cl

    •   Predominant metals (ICP-AES) Al and K

    •   Anion(s) chlorate and perchlorate, some question about the purity of this standard.

      Discussions with Test America yielded no particular reason that a sample that had been produced with only potassium chlorate and aluminum powder could result in a significant perchlorate signal.

    •   Other species NA 



#9 Maserface

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Posted 05 August 2017 - 06:31 PM

There is a wealth of impact ignition data in, Fireworks, the art, science, and technique, by Dr. Takeo Shimizu. Since it's quite obvious that you are serious about this hobby, the relatively small amount of money that this book costs should be of no consequence.

I have a copy to sell you, if you would please pm me.

#10 Richtee

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Posted 06 August 2017 - 03:10 AM

Richtee, is your link for something in the HE section? I get an error message stating that I do not have permission to view that forum.

 

Ah Chit... yes..my bad...it is. Apologies. It does touch on some HE stuff too. altho the germane portion is more a tweaked flash product. I’ll let it lie and others with more “experience” may speak on it.


I like smoke! On food or in the air equally well.

#11 AllisterF

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Posted 08 August 2017 - 03:20 AM

I'm not going to 'advocate' blowing stuff up with pyro comps, so if you just want a 'report' from the target using a 22LR that won't set off over the counter binary targets, why not just avoid pyro altogether and just use compressed air in plastic soda bottles?

 

Use this as a generalization, a typical 2 liter bottle as a general rule has a safe working pressure limit of about 75 psi,  smaller 1 liter bottles have a working pressure of about 100 psi...  At those pressures they are no laughing matter and can still harm you if you are in close proximity...  On this subject I will refer you to this page, it list the psi of over the counter sodas  https://hypertextboo...eemaMeraj.shtml from this you can see where the previous 'safe working pressures' were derived, as the bottles have to be able to handle being shook up in the back of a truck on a 100 degree F day, where the pressures are likely going to exceed 100 psi, especially for higher carbonation sodas like diet Coke (that is why diet Coke is used for those Mentos fountains, it has higher levels of carbonation then other sodas)

 

Anyway with all that said, you should be able to pressurize used soda bottle to 50-75 psi with very minimal risk, before you pressurize it put in some cake flour, chalk powder, left over BBQ or camp fire ash or diatomaceous earth and you will get a very decent report as well as a very decent visual upon impact...

 

This is not something I made up, there are several companies that sell these plastic bottle reactive target systems using recyclable soda bottles and custom made bases or caps, but you can DIY cheaper simply drill a hole in the bottle cap and from the inside insert a rubber sports ball needle valve assembly, duct tape some string or ribbon to the cap so you can find it if it separates and you can reuse it over and over again on other bottles...

 

Do an Ebay search for "Replacement Valves for Soccer" for the valves...  You can also use tire valve stems...

 

There are lots of Youtube videos of these soda bottle reactive targets from manufactures of the lids or base, if you are just wanting a report and visual they work quite well, as I can confirm as I have used them myself...  And best of all much less risk of injury, much less potential for law enforcement hassle and they work for BB guns, pellet guns, blow guns, sling shots or traditional bow and arrow...


Edited by AllisterF, 08 August 2017 - 03:22 AM.

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