SpudFiles

I'm making a stationary cannon for product testing (yes, my job involves making pneumatic canons, be jealous).

I'm looking to change out between two different barrels on a relatively regular basis (2.5" and 3"). They'll both be reduced to 1" or 1.5" for the valve piping (I only need 70mph, so I'm using a relatively small valve).

my question is if anybody has any good "quick disconnect" ideas. The piping will all be steel/iron to satisfy safety requirements (since PVC isn't certified for pressurized air).

I would LOVE something like the following "quick release flanges":






(you can see the QR attached at the top of this one)

Any ideas? Worst comes to worst I'll deal with bolt on flanges, but I'd rather not have to unbolt and rebolt every time I want to switch out the barrel.

Cam-lock fittings?

I'm making a stationary cannon for product testing (yes, my job involves making pneumatic cannons, be jealous).

What products would these be, if we can ask

protective eyewear, can't say more than that, sorry!

where can those fittings be found?

jonathanb wrote:protective eyewear, can't say more than that, sorry!

where can those fittings be found?

Fastenal, tractor supply, MSC industrial, plumbing supply stores...

Man, after 2 days of scouring the catalogs, and I somehow miss those. i need a vacation, ha!

It looks like most aren't rated for compressed air - I assume as long as I get aluminum/brass/steel I really don't have to worry about the thing grenading as long as I stay below the rated pressures? I'd assume it would be the gasket that would go first...

the nylon ones are rated to 150psi, the aluminum to 300, the stainless are 500...

for fluids and particle solids only it appears - and gas and fluids behave VERY differently under pressure breaches than gas! Leaky pipe vs. exploding pipe...

jonathanb wrote:protective eyewear, can't say more than that, sorry!

Sounds cool, wish I could do this for a living.

I wouldn't worry about ratings, after all if this is just to attach to be barrel it will only be under significant stress at the moment of firing, this will be for a short period of time and not equivalent to the pressure in your chamber.

I've used stainless ones at 120 psi as part of a chamber, never had a leak or failure.

I assure you with the pressures you'll be using(i'm guessing 30-40 psi, otherwise you'll way exceed 70mph) grenading and leaking won't be an issue...

I've used nylon camlock as barrel flanges upto 500psi without fail or leak, but 700psi turns them into schrapnel... I've gone up to 1100 psi with aluminum with no leaks...

I worked at one time in a pharmaceutical plant and the fittings in your original post are sanitary fittings, they are designed to be taken apart over and over with minimal tools and to maintain they're reliability.

Yep, I wouldn't even worry about it if it wasn't in a place of business - the only reason I'm using ASME pressure rated tanks, all metal fittings, etc.

Of course, I'm also using a mod sprinkler valve, but those are air pressure rated, really!

One more thing while I've got you guys here - any ideas for a safety switch for a door? So that when the door is closed, the valve can't be triggered. I figured the easiest way would just be to set up a ball valve to "latch" behind the hinge side of the door, so the door can't be open and the ball valve open at hte same time. I'd have to make a new lever for it obviously, but that should be pretty easy.

thomascb21 wrote:I worked at one time in a pharmaceutical plant and the fittings in your original post are sanitary fittings, they are designed to be taken apart over and over with minimal tools and to maintain they're reliability.

Ah ha, that helped me find them! Quick-clamp fittings... go figure. Cheers!

http://www.mcmaster.com/#quick-clamp-tube-fittings/

Now I have choices, thanks all for the help

jonathanb wrote:Yep, I wouldn't even worry about it if it wasn't in a place of business - the only reason I'm using ASME pressure rated tanks, all metal fittings, etc.

Of course, I'm also using a mod sprinkler valve, but those are air pressure rated, really!

Um.... Why? There are metal valves rated for air that will out perform a modified sprinkler valve and they're very affordable ($20). If you're truly worried about certifications and such because you're in a professional environment, there is no excuse for using sprinkler valves.

One more thing while I've got you guys here - any ideas for a safety switch for a door? So that when the door is closed, the valve can't be triggered. I figured the easiest way would just be to set up a ball valve to "latch" behind the hinge side of the door, so the door can't be open and the ball valve open at hte same time. I'd have to make a new lever for it obviously, but that should be pretty easy.

Buy a proper valve. Trigger it with a proper solenoid valve. Run the wiring for the solenoid valve through a magnetic leaf switch (a relay may be required). Voila, a simple system that will not fire if your door is open (or won't fire if it's closed... Whichever way you want it).



edit: And if we're playing the "job jealousy card"... Pneumatic guns are about the tamest things that I get to play with at my job.

D_Hall wrote: Um.... Why? There are metal valves rated for air that will out perform a modified sprinkler valve and they're very affordable ($20). If you're truly worried about certifications and such because you're in a professional environment, there is no excuse for using sprinkler valves.

edit: And if we're playing the "job jealousy card"... Pneumatic guns are about the tamest things that I get to play with at my job.

Any leads on those valves? I wasn't able to find higher performance 1" valves for below $100, and quickly going up from there. Links always appreciated

Most of my job is actually spent in CAD, FEA, field research, and design... the testing is just a fun side job

jonathanb wrote:Any leads on those valves? I wasn't able to find higher performance 1" valves for below $100, and quickly going up from there. Links always appreciated

3/4" quick exhaust valve. Mcmaster-Carr (mcmaster.com) part number 6646K23. $21/each.

3/4" should work for no more performance than you're asking for. If not, run two in parallel.

But really.... For a professional situation, even $100 valves should be in the noise!