I have an idea!

[JS]

Red: vinegar, Black: bicarb soda, Rectangle: pvc, Circle: valve, Line: hose
First open the bottom valve, then open the top one. air will flow out the hose into a water chamber, thus pressurizing the chamber.
Do you think it will work? Its an idea for an auto charging air powered gun.

[DX]

The pressure must be higher on the incoming side of the PC's check valve than the outgoing side in order to move air or water into the PC. This is why hand pumps work so well, you can just push harder to create the necessary pressure spikes that open the valve. This thing might work at first, but will it have enough power to completely fill the PC?

[JS]

the valve is a tap-like thing, turn it to let it flow. not a one-way.

[Poseidon2000]

confusing me....

You fill it with vinegar and soda, and use an air hose? hmmm....
Sounds like a multi-shot APwater cannon to me.

[JS]

The vinegar mixes with the bicarb, and creates lots of gas, so if the hose is connected to the top of a water chamber it pressurizes it and all you need to fire it is a trigger. ill post a better pic later. sorry for any confusion.

[Poseidon2000]

You wouldn't want to shoot that at people...

[isoaker]

Theory may be "ok" at best, but even if it all works and you don't end up accidentally mixing any of the baking soda/vinegar with your water, the smell and lack of control over the amount of pressure generated may lead to serious, undesirable consequences. Smells aside, you'd need to be very careful about not mixing too much together, otherwise you'll end up creating more gas than needed and requiring a good pressure-release safety valve in the system. If you don't use enough vinegar/baking soda, you won't generate enough pressure needed. In the end, not easy to do properly and not recommendable.

[JS]

Im still going to try it.

[soakinader]

Seems like a lot of trouble for something that might not be very effective. However, I would like to look into making a homemade that uses ball valves for controlling flow, gravity for filling the PC, and a CO2 canister to pressurize said PC. It would be like a paintball gun that shoots water. Well, more like a pumpless CO2 powered water blaster.

[JS]

That was the plan, to make a prepressurized pumpless chamber, good idea with the CO2 chamber.

[soakinader]

Yeah! I can imagine it already. "Water fight today? Crap, where's my paintball gun?"

No for realz, the modular gas supply system is an idea. Just need a control valve so that the PC can be de-pressurized and refilled with water whilst the canister is still attached and pressurized.

[DX]

CO2 is a very expensive way to power a water gun. Water, unlike paintballs, takes a LOT more power to move. With a projectile, you can power it with a small amount of very highly compressed gas. With a stream of water, you need high volume, not just high pressure when it comes to compressed gas. Therefore, to use CO2, you need a whole tank. Those common cartridges aren't nearly enough, it has to be a pretty sizable tank. Overly high pressure hitting the water in a sudden and direct manner can also make your stream break up. Laminators slow down streams on purpose.

It would be cheaper and more effective to make a pumpless homemade with a large chamber using compressed air and an air regulator. I still don't think vinegar and baking soda generates enough power. I've used the mixture to pop corks high into the air off bottles, but those things are small, light, and easily put into motion. Water is not easily put into motion with long range. You'd be lucky to get 30 ft and then it has to be remixed for each shot. It would be faster to use a conventional hand pump.

[HBWW]

I'm pretty sure CO2 also carries the risk of cooling the water below freezing point (the compression preventing it from turning into ice, since water is the only liquid that expands when solidifying, if I remember correctly), which can be dangerous when shot at anyone.

The other trouble with a large-chamber and regulator setup is that air is very easily wasted. You need a PC to hold the pressurized water to shoot out, but what do you do once the PC is empty? You end up with a lot of air getting wasted. Perhaps if the air can be used instead to move water from its dormant/non-pressurized source to power up a traditional CPS or LPD air chamber, that could work instead, but I'd imagine the only way to do that could waste even more air.

Of course, we could also manufacture waterballs, paintballs filled with water which will soak with enough shots on impact. But then we might as well just play paintball?

Perhaps the best pumpless setups are those that involve a whole lot of pre-pressurization beforehand, but the blaster becomes useless without a charging station. (i.e. If you're playing in a park without a source of pressurized water to quickly connect to.)

[Fishfan]

CO2 may be expensive, but why not use scuba tanks? They don't hold CO2 (You don't breath CO2, you breath O2). They are only like 5 bucks to charge. The only problem is they are really heavy, so they would have to be used for a stationary cannon(I know, my dad has one). But you could make mini scuba tanks out of PVC.
Endcap---Length on PVC---reducer---ball valve---adapter to water gun. You can attach a shrader valve to charge it with a bike pump.

[Neptune]

That would get so expensive after a little while...

If you want some fancy multi-shot thing, go for HPV. Paintballs use it, it isn't cooled like gas.

[Fishfan]

HPV?
Anyways, $5 is a lot cheaper than CO2. And Scuba tanks have a lot more air in them.