Pneumatic cannon no pumping?

I wanted to build a soda shooting fridge canon like this 
http://www.youtube.com/personalbeerrobot#p/u/3/TVyLuosZ1rY
but I don't understand how the cannon in question works. All pneumatic cannons I have dealt with have required pumping, but this one appears not to require pumping. How does it work?

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rocketman206 years ago
You could make a pnuematic cannon that fires about four rockets (or whatever your shooting) but only filling it once.
dog digger6 years ago
It would probably have a mini air compressor
KarateLover21 (author)  dog digger6 years ago
thanks
onrust6 years ago
I'm just guessing but a gas solenoid valve. I have seen them on several types of compressed air / gas cannons.
1207040872.jpg
KarateLover21 (author)  onrust6 years ago
but what gas propels the can if no one is pumping it?
I seriously hate to be rude, BUT if you can't figure the different compressed gasses..... I'm not going to tell you how to hurt yourself. :(
KarateLover21 (author)  onrust6 years ago
I am not going to hurt myself, I just want to know how he is propelling a can without pumping it with compressed air.