10 replies to this topic

[Prometheus]

Ok, I've heard that SCH 40 PVC works better for a pressure tank than the thinwall PVC, although the thinwall is rated up to 200psi. What do you think should be used, cost is irrelevant, but safety is not.

[CaptainSlug]

Plastic pipe comes in SCH40, SCH80, and gravity flow. Gravity flow or thinwall items are NOT pressure rated as a stand-alone unit.
With anything made out of PVC it is not advised to go above 125-150 psi even if the pipe is rated for a 200psi maximum. PVC is not a great material for higher pressure because it shatters under failure rather than deforming.

[Prometheus]

CS, would you say that the SCH 40 is less likely to shatter than the thinwall at, say, 100 psi?

[King Of Butt Land]

Yes, always use schedule 40 pvc for pressure applications. May sure your fittings are pressure rated as well.

-Butt

[SHADOW HUNTER ALPHA]

CS, would you say that the SCH 40 is less likely to shatter than the thinwall at, say, 100 psi?

Thinwall = Thin wall. Thinly walled objects don't hold pressure well.

Other than that, I would suggest using a double-tank if you are insanely concerned about safety. (When I use the phrase "double tank," it means one pipe inside of another one, with some space in between that can be used to contain a shattering internal tank, and then bleed out the rest so that there is no danger.)

Edited by SHADOW HUNTER ALPHA, 06 February 2007 - 06:03 PM.

[puggy]

I've take aome 2" schd. 40 easily up to 150 psi. many times before. I don't think the pipe will ever fail unless you deside to put like a kajillion psi in it. But if you use it in the cold like outside during the winter (right now) it is tested and proven that the pvc becomes brittle and it will shatter. Wait till spring to use it outside. You also need to be worried about the joints whhere an endcap would be, that would be the most weakest part. Look for the solvent welding course over on spudfiles.com.

[CaptainSlug]

CS, would you say that the SCH 40 is less likely to shatter than the thinwall at, say, 100 psi?

Yes because thin wall (i.e gravity feed) items are not even meant to hold pressure on their own. They're used only for draining applications.

Do not exceed 150psi when filling a sch40 tank.

[King Of Butt Land]

One more thing, the pressure rating on pipes is usually three times less at what the pipe shatters at. Don't get any ideas though... seriously, touch 2 inch pipe at 400 psi and your dead in a second.

-Butt

[KBarker]

The other thing to keep in mind is that although the pipe is rated at that pressure, the glue joints are more variable and could fail at a much lower pressure. Always use the primer and PVC cement for a pressure tank.

[CaptainSlug]

And if you have an application that requires a tank capacity beyond 150psi then you need to get a tank rated for HPA. Paintball HPA tanks are not very expensive (start at $50).

Edited by CaptainSlug, 06 February 2007 - 09:07 PM.

[Prometheus]

I've also looked at modding a soldering torch (propane or butane) fitting to attach to standard NPT fittings, but it doesn't look to promising. The tanks are a great size to use, but due to the special threaded end on them I don't see it being an easy job.