SpudFiles

I went to all the local hardware stores and saw that all the fittings above 2" did not say NSF-PW, just NSF-DWV. So I asked someone in the plumbing department in Home Depot wether or not the fittings were pressure rated since they only said DWV, he said they were and he had built numerous potato guns.

I thought back to what Joel said in his FAQ and decided to just buy the parts I knew were pressure rated, the fittings to make the pass thru barrel from Burnt Latke. I'm planning on buying the rest of the fittings I need from Plumbingsupply.com, are they a good supplier? I'm going to purchase some 3" couplings, a 3" female adapter, a 3" threaded plug and a 3" to 2" reduction coupling.

I'm building my first combustion spud cannon, my previous experiments were smaller pneumatic nerf guns. The chamber is an 18" long piece of 3" sch40 and the barrel is going to be a 48" long piece of 1.5" sch40, it should be a 1.5:1 ratio if I did my calculations right.

combustions are fine with dwv.

not all DVW fittings ar fine. make shure they are not cellular core. get the black ABS fittings.

plumbing supply is awsome if you need more fittings check http://www.mcmaster.com

SpudStuff wrote:not all DVW fittings ar fine. make shure they are not cellular core. get the black ABS fittings.

plumbing supply is awsome if you need more fittings check http://www.mcmaster.com

ABS is a cellular core polymer, in fact i dont think you can even find solid core ABS pipe. You might be lucky to find pressure rated ABS pipe but why would you bother? pvc is much easier to find and is almost always pressure tested, and if it isnt it usually says in big bold letters NOT FOR PRESSURE USE

dont use ABS..

They do sell pressure rated ABS. In fact, it's rated for compressed gas. Nevermind that you won't find it, that's not the point.

ABS is a polymer... the cellular core bit is detached and makes no sence outside of the plumbing domain.

My personal take: typical ABS (cell core) is probably second rate for typical guns, but if you are going to to something 'stupid' - acetalene/O2 for instance - it's alot less likely to kill you. (due to it's mode of failure)