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No pressure rating. :-/

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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No pressure rating. :-/

Unread postAuthor: bLah » Mon Nov 12, 2007 12:30 pm

Yesterday I went to ACE Hardware store and bought all the PVC stuff and PVC cement for a spud cannon. Now, I'm seeing all this stuff about it needing to be pressure rated.
My pipes only say DWV and theres no PSI on it.
Did I just blow 20$ or could I still use it?
What are the possibilities of it blowing up and if it did blow, how would it blow? Like, would the cement break and the pieces fly apart or would it shatter into pieces?
Why do those little mini spud guns not blow up, the ones made with a pen and a pill bottle?
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Unread postAuthor: VH_man » Mon Nov 12, 2007 12:32 pm

yeah, you can use it as a target.......

go buy some pressure rated pipe. your life isnt worth a few bucks.

EDIT: sorry its a combustion. I BELIVE that DWV is fine for a combustion. aka go ahead and use it. if this was a pneumatic..... it would be useless.
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Unread postAuthor: williamfeldmann » Mon Nov 12, 2007 12:53 pm

For combustion:
If you are doing a simple spray and pray, you will fine, If you want to work with metered propane, you should consider returning the pipe for rated stuff. Combustion creates relatively low pressures and not fast or prolonged like pneumatic.

For pneumatics:
People will tell you that DWV is safe up to like 70 PSI. DWV is not safe, at any pressure. When it fails, it will not give any warning, it will just blow up. Your particular parts might be able to hold 400 psi, or 45 psi. Since they are not rated, they are not tested, so no one knows. DWV is not held to the manufacturing standards that PW is held to. PW still has minute flaws that can cause failure. DWV is much more likely to have them. DWV only needs to be able to handle the pressure of a gravitational drain system, so maybe 20 psi max. Since it doesn't have to be stronger than that, you are basically putting your nuts in the hand of the lowest bidder for the particular retailer you bought it at.

Cleanout caps are not pressure rated.

Bell reducers are not pressure rated.

All fittings, bushings, couplers, reducers, etc should say NSF-pw on them.

Schrader fill valve should be threaded through 2 layers of pvc for safety, but if the plug is thick enough you will probably be fine.

(Yeah, I copied myself from earlier, but it applies)
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Unread postAuthor: BC Pneumatics » Mon Nov 12, 2007 1:36 pm

williamfeldmann wrote:(Yeah, I copied myself from earlier, but it applies)

Don't worry about it. As far as I am concerned, we need a button right after the phpBB tags that inserts exactly what you said into any post.
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