Pnuematic Cannon Making Very Loud Noise....!

[humedm]

Hi! I recently made a pneumatic cannon using a 1" sprinkler valve. The build is basically two feet of 3" PVC for the chamber to the sprinkler valve to a 1" barrel that's about a foot long. I designed it to be triggered by an electronic push button and have switchable barrels if I wanted to use a different kind.

The problem though is every time it's triggered it lets the air out fine but along with a very very loud "quack" sound coming from the sprinkler valve. It seems as though the valve is not opening all the way I assume, but that doesn't make sense because it is getting 27 volts. Perhaps reduction from 3" to 1" pipe is causing this. Any thoughts? Most of the pneumatic cannons I've heard don't make any loud noise and only a whoosh of air. And it makes this sound at only 20 PSI.

Let me know what you all think and if you have any ideas to get rid of the sound.

[mark.f]

The valve is "honking", which happens when your pilot doesn't let out enough air and the diaphragm attempts to reseal itself rapidly. The included solenoid is usually very low flow, designed to pilot the valve at normal water pressure. Since air is compressible, you usually need more flow for your pilot valve. You can mod the valve by tapping the lid to accept a larger pilot valve, or attempt to drill out the existing pilot hole under the solenoid.

[jimmy101]

You can search these forums for "honking" for a number of posts about the problem.
There is also a brief page on the wiki at spud_wiki/index.php?title=Honking and spud_wiki/index.php?title=Sprinkler_valve_modification