Newb with a few questions for the more experienced!

[Jakerz]

I've been lurking around the site for a few days now and have found an insane amount of great info, thanks for that! But I do have a few questions that I can't really find direct answers to.

First, I plan on building a metered MAPP Gas cannon, I have all the ratios and dimensions I need already from searching this site and Burnt Latke. I can't make up my mind on the ABS vs PVC debate (or war, lol), I like the test results I see from ABS over PVC as it splits instead of exploding. BUT I don't know where I can find solid core ABS pipe in my area, anyone know a good source to order it online?

Second, how much of a pressure spike are we talking about with say a 4.5:1 MAPP Gas mixture? Combustion chamber would be around 225 ci.

Last but not least, I know Lowes has Sch 40 foam core ABS pipe in the sizes I would need to build the cannon. I've read numerous people say that the pipe doesn't need to be pressure rated to be used on a combustion cannon, but I guess my second question needs to be answered before I feel totally comfortable with using this type of pipe, would prefer solid core so sure.

How much of a deathwish would I have if I made a cannon with that stuff? lol

Thanks in advance,
Jake

[Binder17]

Jakerz,

Go PVC in my opinion. I've never had trouble with it in the 10 years I've used it. Even with nonpressure rated PVC, it holds up well. However, I would use pressure rated just to be safe. Happy Spudding.

[Ragnarok]

I can't make up my mind on the ABS vs PVC debate (or war, lol), I like the test results I see from ABS over PVC as it splits instead of exploding.

In my opinion, you're much better off building something that doesn't fail in the first place than trying to produce something that fails "safely". If you can find suitably strong ABS pipe, then that will be all well and good, but an ABS cannon that does fail is inferior to a PVC one that doesn't (and, as you've mentioned, it's easier to find PVC pressure pipe).

How much of a deathwish would I have if I made a cannon with that stuff? lol

It's not likely to fail, but I'd still recommend against it.

Second, how much of a pressure spike are we talking about with say a 4.5:1 MAPP Gas mixture? Combustion chamber would be around 225 ci.

In a basic combustion spudgun, chamber volume is fairly irrelevant to the pressure generated. You should expect pressures might hit about 100 psi, although the rapid spike and the temperatures generated mean that's less friendly to the launcher than if it were a static pressure*.

*Although in general plastic combustions are probably safer than plastic pneumatics at the same pressure. The risk with pneumatics though is dropping them while they're under pressure!