problems with burst disk cannon

[A-98]

This weekend I was bored so I made a small burst disk pneumatic. It was originally designed to be triggered by a blowgun and I assembled it so.
However when I pump up the 2 chambers to their proper pressures and go to trigger it it releases the air in the secondary chamber, bursts the primary disk, but then the main chamber empties thru the blowgun. I know that the pressure is great enough to burst it, yet it doesn't.

Is it as simple as having too small a chamber(18" by 3/4") and therefore not enough flow? It was going to have a 2" by 12" chamber, but my ace was out of couplers.

thanks !
Bryce

[killagorrila99]

Well, Theres no reason why it shouldnt work. I'm stumped.

[frankrede]

can you pst a diagram of your setup, I am a bit confused.

[A-98]

ya. working on a pic. im not that skilled with comp drawing.

[A-98]

http://s157.photobucket.com/albums/t51/ ... rgem-1.png

there we go

the blue is the burst disk, and the rest if pretty strait forward.

the blowgun empties the plus(chamber) and bursts the right one of the 2 disks. then the left disk it supposed to give, but doesnt, and the air vents thru the blowgun.

[killagorrila99]

I can see whats wrong. Use a weaker material for the left burst disk and it will work. Whats happening is as the first disk bursts, the chamber volume increases, making the pressure drop before it can reach the second disk, thus not bursting it.

[A-98]

yarg!

I should have thought of that...going to test it.
will report if it worked in the morning, right now i have to do spanish homework (curse you homework!!)

[A-98]

ya, It worked.

I need to figure out the exact pressures of the burst disks but for now it worked.

Unfortunately the union got stuck this morning and i cant get it apart. any suggestions.

[medievalman]

put it in the fridge for a couple of hours and the cold air will make it shrink, then heat up the female part to enlarge it.