[SML] Cannon burst from air cannon

[Jerry Durand]

On pumpkin cannons I've seen ball valves with a way to turn it fast.  
Could be as simple as a spring with a rope you cut.  If you needed 
electrical control, a pneumatic piston fired by a solenoid.

For the lowest of dead simple, a wheel for a handle on the valve, wrap 
with rope... yank.

On 09-Dec-25 21:40, Joe via Stagecraft wrote:
> First, it is good that Jerry Durand reminded folks about the explosion 
> risks with PVC pipe.  I reminded the folks working with me about that, 
> so I at least reduced the temptation to see how loud they can make 
> it.  I accidentally created a safety feature on my system by using a 
> bicycle pump that was designed for higher volume and lower pressure. 
> Taking it to 70psi was the maximum they had enough weight to pump.
>
> I understand the Cv rating (resistance to air flow).  When I searched 
> for blast valves for dust collection systems.  However, all the ones I 
> found were ball, or knife-gate valves.  None automatically opened at a 
> certain pressure, or reset. They were simply valves to direct the air 
> flow to the tool being used.  I am puzzled why they called them blast 
> valves.
>
> Here is a quick sketch of how I might imagine a type of resettable 
> high pressure valve might work.  Structurally, it is like the air 
> outlet of your clothes dryer, or bathroom exhaust fan. However, I 
> added a magnet to hold the flap closed until pressure exceeds its 
> holding power. The spring loaded hinge on the flap would then close 
> the flap, so it can be used again.
> Inline image
>
>
> But, I can't find any type of air valve like this, or that is designed 
> for releasing at a fairly high pressure (i.e. 60psi).
>
> Jon, can you provide a link to the type of valve you were talking about?
>
> -Joe
>
>
> On Monday, December 8, 2025 at 11:39:25 PM EST, Jon Lagerquist via 
> Stagecraft <stagecraft at theatrical.net> wrote:
> For valves I found that "blast valves" designed to clean dust 
> collection systems do a great job. I remember them having a CV of 
> about 50.this means they are making a big hole very fast so lots of 
> air moves quickly, producing a good sound with or without a cap.
>
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