how to best burst a burst disk?

[JDP12]

hey all- I've got a bunch of paintball games coming up, and i've decided to build a grenade launcher/shotgun style gun. I've decided to use a burst disk design similar to Davidvinai's, but with a little differences.

I want to have a small chamber to give me slightly more power, but i have a question about that-

here are my two options as I see them.

1) have a ball valve from air source to a chamber, and have the pressure in chamber build up till burst disk fails.

2) fill chamber, then have a ball valve between chamber and burst disk that would open- and then air would go through ball valve to the burst disk


I think option two might give me a bit better build up of air pressure and thus a power increase, but what do you guys think?

So I drew up a diagram anyway..

<img src="http://i157.photobucket.com/albums/t79/ ... 1222881201">

[ALIHISGREAT]

a pneumatic ram behind the disc to puncture it.

[psycix]

Option 1)
Probably one of the most powerful and easy options.
Downside is that once it blows, air keeps rushing out until you close the valve.

Option 2)
Probably less powerful due to valve opening, but it will "respond" faster then option one, where the resevoir yet has to fill.

ALIHISGREAT's suggestion.
3) Pneumatic ram/punctured BD.
Probably. Low delay, no flow constriction, best of both worlds.
Downsides: Complex construction.

Another option:
4) Burst disk cascade.
Most powerful option in my opinion. Short delay.
Downside is the extra hassle with reloading burst disks and pressurizing.

[JDP12]

what is burst disk cascade psycix? could you elaborate a bit more on that?

I"m not too familiar with it- I'll do a quick search when i get home though

[Demon]

Just put a pin on the butt of your projectile and let it go down the barrel:




like a real mortar

[ALIHISGREAT]

i think a burst disc cascade is where you have two burst discs.

the one closest to the barrel is set to burst at 30 psi of whatever, then the chamber side one is set to burst at 80psi... so you fill the middle with 20psi and the chamber with nearly 100psi so only when you empty the middle chamber, the discs burst.

[JDP12]

demon- not really gonna work when i'm trying to build a multi-shot grenade launcher.

so you fill the middle first, then the chamber, and the chamber side one doesn't burst because there is 20 PSI holding it back- so when it dumps, the 100PSI burst s the 80PSI, then it bursts the 30 PSI.

the problem i have with a burst disk cascade is it'll take too long to reload, and since i'm trying to use preloaded cartridges- i'd have to put a burst disk on the chamber each time which isn't hwat i'm looking for- so i think i'll go with my second option

[SpudUke5]

Isnt that also known a triggered burst disk?

[DYI]

Option 1 is the most powerful, option 3 is the most convenient, option 4 is slow to reload but allows near-instant trigger response combined with high power, and option 2 completely defeats the purpose of using a burst disk, as the disk will have ruptured before the BV is even a quarter of the way open.

[JDP12]

hmm ok.... so how would i go about creating a pneumatic ram and installing it?

[Hydra]

Just have some kind of bendy material with a nail on the end. The air will push the bendy thing, which pushes the nail onto the burst disk.
Yeah i know thats not that great but its the basic idea.

[JDP12]

ok so general consensus, pneumatic ram or option one here?

[starman]

[peek's head in the room] .... You could always build a small combustion to do the job very efficiently, unless of course it isn't allowed in your location or on your paintball field.

[Davidvaini]

I actually like the ball valve right before the burst disk... this way it would be a lot easier to carry it around..

[ALIHISGREAT]

maybe instead of a pneumatic ram, maybe a firing pin could be used, with a spring loaded pin that is released with a proper trigger?