Interesting firing valve used in air cannon, might be worth investigating

Guides and discussions about building water blasters and other water warfare devices such as water balloon launchers.
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AmaIro18
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Interesting firing valve used in air cannon, might be worth investigating

Post by AmaIro18 » Wed Oct 03, 2018 6:57 pm

https://www.youtube.com/watch?v=G1VCZEX ... e=youtu.be

In this video this guy (youtube channel NightHawkInLight) makes an interesting firing valve for his air cannon that operates based on pressure differences. At about 7:50 he modifies it so that his air cannon could fire at a push of a button attached to a sprinkler valve.

Some modifications would need to be done if we wanted to try using this for a water blaster, like being careful about the pressure chamber orientation or possibly using a larger drilled hole in the firing valve. Other than that, I'm not sure how this firing valve would perform in a water gun. What do you guys think? Has anyone tried anything like this before?

SSCBen
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Re: Interesting firing valve used in air cannon, might be worth investigating

Post by SSCBen » Wed Oct 03, 2018 8:49 pm

"Air piloted" values like this have been used for a long time in air cannons. I don't think anyone has tried this sort of design for water guns. The main problem would be that the pilot volume needs to be refilled with air after each trigger pull. If you use tap shots I imagine this will exhaust your air supply too quickly. Maybe it's worthwhile with a design that keeps the pilot volume to a minimum, but typically we want larger pipes that would make that difficult. Also, the flow path is likely to generate a lot of turbulence unless you figure out a way to make a good "inline" pilot valve, i.e., one that allows flow to go around the valve head.

For air piloted valves, it would be better to use the pinch valve Tim found. That has a fairly small pilot volume and a good flow path. It's expensive and also fairly large, but as Tim showed it has excellent performance.

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Re: Interesting firing valve used in air cannon, might be worth investigating

Post by SEAL » Thu Oct 04, 2018 5:21 am

SSCBen wrote:The main problem would be that the pilot volume needs to be refilled with air after each trigger pull. If you use tap shots I imagine this will exhaust your air supply too quickly.
Perhaps you could use a dual-shaft pump; one that pumps water into the chamber as normal, and another smaller one that just pumps air. The air gets refilled automatically just by pumping up the soaker. I'm sure there are simpler ways to make a trigger valve though.
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SSCBen
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Re: Interesting firing valve used in air cannon, might be worth investigating

Post by SSCBen » Fri Oct 05, 2018 6:35 pm

That's possible. I probably would prefer having a separate air tank that's filled by a small bike pump for simplicity, though. Refill the air tank when you are refilling your water reservoir.

Another possibility is to use a system with a built in air supply already, like a CAP design (like that used by Tim) or a low pressure drop design which has a large unregulated air chamber. Both have their disadvantages.

CDMT
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Re: Interesting firing valve used in air cannon, might be worth investigating

Post by CDMT » Wed Mar 27, 2019 12:14 am

I already made the valve used in this in a water gun. If you are using it to make a single shot gun then it's great. But for a rapid fire design it's too slow to reset the valve ie every trigger pull however slight fires it all the built up pressure at once.

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