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Smoke-generating Silencers

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Smoke-generating Silencers

Unread postAuthor: Tsukiten » Thu Dec 04, 2008 1:36 pm

So I basically got the idea from this video posted on YouTube:
http://www.youtube.com/watch?v=BoXSuAT3 ... -fresh+div

What you see there is a plastic/metal cilinder attached to some Co2 handgun. Inside the cilinder there is a cardboard (or so they say) tube with holes in it, and then filled with some kind of white powder. The gas from the shot draws out powder from the holes and generates this "gunpowder smoke" effect.
It looks really cool! :D

I want to apply this to my bb combustion but I'm worried about the "flames" from the combustion will ignite the powder in some way (this can actually happen, if there's enough air between the powder particles).
So my question is:
Will this happen? And if so, can it be dangerous in some way?
Also, shooting flour out of a combustion might give some nice effect, if it doesn't ignite.
(On the other, side it might be a heck alot of cooler if it did :D but dangerous)

Thanks for reading, and hoping for some replies!
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Re: Smoke-generating Silencers

Unread postAuthor: Ragnarok » Thu Dec 04, 2008 1:57 pm

Tsukiten wrote:So my question is:
Will this happen? And if so, can it be dangerous in some way?

It's possible it will happen, even if you wouldn't expect the particular dust to be flammable. Suspended dusts can explode. That's why there are serious no smoking rules in flour mills, paper factories and other such places..

However, in your case, if it happens, it probably won't be dangerous, assuming you're being responsible, and nothing you don't want to destroy is anywhere close to being down range - as it's not contained, so it will be more of a mini flame than an explosion.

Not saying I'm recommending it though - just that it probably won't be dangerous if you're responsible. It does add extra hazards though.

If you're really fussed about muzzle smoke, you could try a mid-high pressure/mid volume pneumatic, because firing those causes condensation of the water vapour from the rapid decompression, so you get some cool smoke from the muzzle on firing.
Also cool if you have an easily opened breechloader, as you can open it after shooting and get curls of vapour out of the back of the barrel - basically small quantities of artificially created fog/clouds.

I have a video that shows this quite nicely, I'll track it down for you.

Also, shooting flour out of a combustion might give some nice effect, if it doesn't ignite. (On the other, side it might be a heck alot of cooler if it did but dangerous)

Seen a youtube video of just this, for antiqueing a person. First time it didn't ignite. Next time - they got caught in quite a sizeable fireball, but fortunately avoided major injuries.

Definitely not recommended.
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Unread postAuthor: jackssmirkingrevenge » Thu Dec 04, 2008 1:59 pm

Rather than powder and risk a dust explostion, why not have something which actually does burn slowly giving off smoke, like strands of yarn or something similar.
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Re: Smoke-generating Silencers

Unread postAuthor: Tsukiten » Thu Dec 04, 2008 2:19 pm

Ragnarok wrote:Seen a youtube video of just this, for antiqueing a person. First time it didn't ignite. Next time - they got caught in quite a sizeable fireball, but fortunately avoided major injuries.


Was that perhaps some kind of saw-dust cannon with a flare in the middle?

And about the vapour plume: At what kind of pressures will this start to occur?

@ JSR:
Yeah I'd gladly accept any good alternative but I think yarn might not develop enough smoke to have a nice visible plume at the end of the barrel (which measures about 29 inch, 6mm in diameter)
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Unread postAuthor: spudamine » Thu Dec 04, 2008 2:23 pm

You risk an explosion with any powdered carbohydrate or organic material in general (talking about the real meaning of the word not the 'green' usage), but you should be fine with something inorganic like chalk dust for example.
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Unread postAuthor: jackssmirkingrevenge » Thu Dec 04, 2008 2:26 pm

Cotton wool? You're the one who wants smoke when everyone else is doing his best to eliminate it, do some testing :P

Small "silencer" covering a few ports at the end of the barrel, with a removable cap to fit various materials inside, and get shooting :D
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Unread postAuthor: mark.f » Thu Dec 04, 2008 2:30 pm

I would use something very fine so that the smoke would be suspended and not sink to the ground like the stuff in that video.
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Unread postAuthor: Tsukiten » Thu Dec 04, 2008 2:34 pm

spudamine wrote:You risk an explosion with any powdered carbohydrate or organic material in general (talking about the real meaning of the word not the 'green' usage), but you should be fine with something inorganic like chalk dust for example.

jackssmirkingrevenge wrote:Cotton wool? You're the one who wants smoke when everyone else is doing his best to eliminate it, do some testing :P

Small "silencer" covering a few ports at the end of the barrel, with a removable cap to fit various materials inside, and get shooting :D


For this idea I'm going to use a silencer I made which is already filled with cotton wool and has a removable cap.
And I can't see a plume of smoke coming from it :shock: Not even the smell of burnt cotton wool. (Probably due to the barrel length)
Thanks for the suggestion, though. (maybe IN the chamber? I'll try)

And yeah I guess I should use non-organic material for this. But other than the chalk dust you suggested me, I can't come up with something else. (Also, is chalk made from some kind of burnt metal/metal oxide?)
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Unread postAuthor: jackssmirkingrevenge » Thu Dec 04, 2008 2:48 pm

A few drops of diesel :D
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Unread postAuthor: Tsukiten » Thu Dec 04, 2008 2:52 pm

jackssmirkingrevenge wrote:A few drops of diesel :D

That would mess with the fuel:air ratio, right? :shock:
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Last edited by Tsukiten on Thu Dec 04, 2008 2:54 pm, edited 2 times in total.

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Unread postAuthor: jackssmirkingrevenge » Thu Dec 04, 2008 2:54 pm

Nope, but the problem seems to be (if you want to achieve smoke by actual combustion) that the gasses reaching the end of your barrel simply aren't hot enough to ignite anything. Poo.

Talcum powder :D doesn't burn as far as I know, unless it's made of corn starch.
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Unread postAuthor: Tsukiten » Thu Dec 04, 2008 3:07 pm

jackssmirkingrevenge wrote:Nope, but the problem seems to be (if you want to achieve smoke by actual combustion) that the gasses reaching the end of your barrel simply aren't hot enough to ignite anything. Poo.

Talcum powder :D doesn't burn as far as I know, unless it's made of corn starch.


Oh, yeah it seems to be mineral... (Just checked wiki)
Sooo is it that it just won't ignite or should I assume nothing will be ignited at the end of the barrel? :shock:

Also, things at the end of the wiki page look kinda scary...
http://en.wikipedia.org/wiki/Talc
(under "Safety")
Yeah everybody uses this stuff but I don't think everyone exposes this stuff to hot gasses every day :roll: Just wanna be sure y'know
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Unread postAuthor: jackssmirkingrevenge » Thu Dec 04, 2008 3:10 pm

Tsukiten wrote:Sooo is it that it just won't ignite or should I assume nothing will be ignited at the end of the barrel? :shock:


If it's not even charring cotton wool a little I think it's safe to say that this is the case.
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Re: Smoke-generating Silencers

Unread postAuthor: Ragnarok » Thu Dec 04, 2008 3:41 pm

Tsukiten wrote:And about the vapour plume: At what kind of pressures will this start to occur?

Well, with enough C:B ratio and chamber volume it will comfortably start at about 5 bar.
With lesser chamber volumes or smaller cannons, you'll need more pressure, but 10 bar would be enough.

Video of HEAL doing a particularly spectacular vapour thing at 300 psi can be found here.
That's a higher resolution version of the clip (with cleaned up image and audio - couldn't do anything about the smell) than can be seen in the Youtube compliation, and so you can see the vapour from both the muzzle and the breech.
This clean up also includes the separate, higher quality, sound recordings I made when filming, which I couldn't use when I made the original video in Windows Movie Maker - it wouldn't let me have both the music and the additional sound layer at the same time, so it was lost in the original editing.

Trivia fact: What most people have no concept of is that is only part of that take. HEAL was fired twice in one video take, and it would have been done in about 10 seconds from the previous shot. However, I fumbled the reload very badly, so I cut all that out.

It was getting too dark, and I was too tired to do another take, so it never made it into the video. The rest of it could have gone in the outtakes section, but it didn't wasn't very funny, and didn't match up to the "Click-Click-Bollocks" clip. :D

For the absolute purist, a fuller version of the take with both shots in can be found here.
You can probably see why I left it out, far too much fumbling. The other thing was that leaving it in wouldn't have allowed the main theme of the background music to play over the credits - believe it or not, I was trying to match it up slightly.
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Unread postAuthor: john bunsenburner » Thu Dec 04, 2008 4:02 pm

I have found this condensation plume to occur at 100psi+. The only idea I can supply is to use a ground up mixture of potassium nitrate and sugar(smoke mix). If you grind it up really finely it will ignite and produce a cloud of smoke, it is cheap and safe as long as you use only small amounts. You could even have different colors but i doubt that is what you are looking for. If you decide to do this, I recomend a ratio of 13:7 (KNO3:C12H22O11). Maybe this helps.

I hope this post is not against the rules, the mixture is not a true explosive, if it is regarded as one on this site(really the mods decision), then i am sorry and i ask you to delete my post.
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