Double barreled air cannon

[Jeremy] wrote in to show off his latest creation. he has built a two barrel pneumatic air cannon. Eschewing the traditional approach of having a single barrel and pressure chamber for his spud gun, [Jeremy] wanted to have a double barreled version. Since he was doing this pneumatically, he had to rig up a way to maintain pressure in each barrel independently of each other, as well as trigger them independently. While we can all agree that one way valves and sprinkler valves aren’t ground breaking, it is nice to see it all laid out and tested. We now have the blueprints if we were so inclined to create our own version.  You can see him testing it out by filling the chambers with water and sploooshing that all over the place after the break.

Comments

  1. JC says:

    Thx for the writeup. How ’bout a link to the site?

  2. Brian says:

    Looks like it needs some sort or apparatus to hold the barrels together towards the end, all that shaking and wobbling cant be good on the joint!

  3. PocketBrain says:

    Needs more creme fraiche.

  4. JC says:

    Here’s the article if you’d like to see it: http://www.jcopro.net/2011/05/08/the-double-barrel-pneumatic-air-cannon/

  5. Ryan says:

    Lol

    Pressurizing PVC pipe and not even suggesting to use schedule 40 or 80.

    At least with thicker PVC pipe you lower the chance of blasting shrapnel into your face. These kinds of projects are one of the few where I genuinely believe there should be a mention of safety.

    Considering the number of people who read these sites, I’m sure there have been at least a few cases of a kid going to home depot and blowing his face off with the cheapest tubing he can find.

  6. Metalwolf says:

    The link is there. Look at the second sentence closely. It was nice when HaD put actual links at the bottom.

  7. Hackerspacer says:

    Please DO NOT put pressurized air into PVC pipe. Don’t do it. Use a more suitable material.

  8. Anonymous says:

    @Metalwolf, how… Orwellian.

  9. me says:

    Ok, look people:

    What _percentage_ of kids who make things in garages have made a pressurized PVC cannon. I know I did.

    How many People have blown themselves up/ or embedded shrapnel in themselves?

    How come I can find a dozen anecdotes of people maiming themselves with a hair spray spud guns, and not one involving a PVC pressure vessel rupture?

    YES, PVC is brittle and makes sharp shrapnel; this is a poor failure state, especially for something you hold close to your body.

    That said: The limits are written right on the tube, and anyone patient enough and willing to spend the extra money on a Air cannon(over hairspray) project is probably smart/conservative enough to pay attention to limits, and be wary of stressing out their new project. Add the conservative ratings, and you would have to intentionally be dumb to pop it.

    And you KNOW that the media would have made a fuss about it if kids were spraying themselves with shrapnel. I Remember they made a fuss about traditional spud guns.

  10. Hacksaw says:

    @me Well Said! I have built many pneumatic air cannons (working on plans for a pneumatic Gatling gun presently) and have NEVER had a failure involving the pipe itself…I have had joints pop but never a tube. If you are that concerned you could drill the pressure vessel and put in a relief valve with a slightly lower rating than what the tube is rated for.

  11. willow says:

    The pressure on the tube is the rated static pressure of water at a given temperature, not air. You have to use a pressure derating calculation to make the best determination for your maximum operating pressure given temperature figures.

    That doesn’t take into acocunt for any sudden shock from dropping it, which stresses glue joints.

    And it’s good to have a gauge and a blow-off valve.

    Regardless of any of this he’s using two non-pressure-rated DWV fittings. Borrowed time would be the appropriate phrase.

    Aside from the lacking safety, it’s really neat. Cannons like these are fun as hell.

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