SpudFiles

What do people think is better?
who has had pvc guns explode versus abs?

Don't take my word on this, I'm not completly sure, but I've heard that abs USUALLY isn't pressure rated. You might be able to get it that way; not sure here. For a combustion it should be perfectly fine though. As to a pneumatic, I personally wouldn't trust the stuff.

This topic has been covered many times before, nboth have their strenghts and weaknesses(SP?).
Now I enjoy the fact that you are concerned with safety you should have searched for one of the many topics going into teh details.
Bottom line ABS shouldn't be used in pneuamtics and can be used in Combustions.

Well I know somewhere that does up to 15bar rated ABS pipe. Can't see why thats unsafe for a pneumatic.

Okay, I have asked this question many many times, and done this research many times, so I can cover the issue.

It depends what kind of gun you want :

For a Combustion gun : ABS is safe to use : I even recommend it over PVC. Yes, ABS is usually not pressure rated, but the pressure created by the explosion in the chamber is no where too powerful or too long to be a problem. And if there IS a problem, and the gun fails, ABS tears, while PVC shatters. It's still a matter of choice.

For a Pneumatic gun : BIG NO NO. Never, NEVER, N-E-V-E-R use ABS in a pneumatic, even if you can find some that is prsssure-rated. The molecular structure of ABS cannot handle repetitive pressure. It's gonna hold fine for the 10 or 20 first shots... but then after.. POW.

Right....

So when someone goes and buys 15bar ABS pipe for pumping water about at 10bar (145psi) with the pressure peaking and dropping every now and again that pipe is going to fail?

Yes water isnt the same as gas but even pressure is even pressure.

You said it yourself.. Water isnt like air.

Pressure however is pressure and both distribute it evenly because they are liquid substances.

Is it proved anywhere that pressure rated ABS is not good for pneumatics or is it a myth from tales of people using unrated ABS?

The pipe cannot handle the rapid increasing and decreasing of pressure.

Go ahead and try. I don't care. But I'm sure you will when you have plastic shrapnel embedded in your face.

Who said anything about doing anything?

Its a discussion.

Wow, people here are taking this discussion personal... Yes this topic has been covered a number of times. Stickying one of these conversations might be a good idea.

I’m one that isn’t such a 'dooms day' on ABS, although I don’t use it on pneumatics because of my own standards. I often see 2L bottles made out of what I believe to be Polyethylene, which if I also recall correctly has a lower, or similar tensile strength to that of ABS. Such bottles are taken to ~100PSI. Since there is two thin layers of solid ABS, that are encompassing the foam core, why would one not expect it to hold pressure when the thickness of the plastic is similar to that of a pop bottle?

Now why should you not use ABS? Well hell there is PVC out there, with a cost relative to that of a ABS system, and this thing is obviously held to higher pressure standards as its cross section is entirely solid.

Although I must say that ABS on combustions is really nice. The ABS is very light weight compared to that of PVC, its black [this means it 'hides' surface errors better, and its black glue very well], and most of all its tuff as far as nature goes. I have a ABS gun that I just leave on the porch or on the front lawn. I never bring it in, yet it hasn’t seem the least bit bothered by the elements. Its been beat by the climaxed by the 115 degree summer heat, and frozen by temperatures around 15 degrees. Its probably been living out there two years now. Heck it got snowed on about 3 nights in a row this week.

Well the only thing is a soda bottle is flexible and abs like isnt.

Okay.. so a little precisions of my POV.

Water isnt exactly the same thing, because water is just not the same thing, maybe it has something to do with volumic mass? I'm not exactly sure.

Personally, I will never recommend using ABS on a pneumatic, because I know it isn't safe, and I would never try. I would have a big conscience problem if I told someone : oh yeah, you can use ABS on a pneumatic, even if I told him/her that there was a potential risk of failure.

Water and air at the same pressures exert the same force on the pipe. It's just that if the pipe pops with water in it, the water does not expand. Air on the other hand, rapidly expands and takes the ruptured plastic and violently throws it at you.

I asked my dad, who is an engineer, he says that water pressure is limited by its volume, because water is considered uncompressable. As for air... sky is almost the limit.