Help Identify This T-Shirt Cannon Robot Please

[BBray_T1296]

Originally Posted by Cory

I look at this and I see maimed students.

PVC as a pressure vessel is very bad.

PVC is what we use for our t-shirt cannon. We crank up our shoulder fired bazooka to 155PSI and blast shirts over our football stadium stands from the track. We have had the cannon since at least 2008 and have not overhauled it since it was built.

[Cory]

Originally Posted by BBray_T1296

PVC is what we use for our t-shirt cannon. We crank up our shoulder fired bazooka to 155PSI and blast shirts over our football stadium stands from the track. We have had the cannon since at least 2008 and have not overhauled it since it was built.

Just because it hasn't failed doesn't mean it isn't horribly unsafe.

[bEdhEd]

Go with metal!

[Donut]

You can get a good sized metal air tank for cheap. The T-shirt shooter we built on 498 back in 2007 used a 5-gallon Campbell Hausfeld air tank from Walmart for under $50, and we just filled it with 2 kit-compressors in parallel. Didn't have to be replaced until a year or so ago, when they found some water starting to pool inside it. Since we didn't do any maintenance on it for 6 years I'd say that's a good life span on it.

The barrel on ours is PVC, but unless you jam it shut the odds of the barrel shattering before the t-shirt is dislodged are pretty low.

[billbo911]

Originally Posted by Cory

I look at this and I see maimed students.

PVC as a pressure vessel is very bad.

Originally Posted by Cory

Just because it hasn't failed doesn't mean it isn't horribly unsafe.

+1

This is extremely sound advice!
We stopped using PVC as our pressure chamber on our T-Shirt cannon because of the risk potential. We too have never had a failure, but the risk just didn't make it wise to use PVC.
We switched to ABS. It's cheap, easily available, easy to machine and has a failure mode that is safe. ABS will blister out, and then the blister "herniates". No explosion, no shards, no injury. Additionally, we have also never had a failure with ABS.
So, there really is no reason to use PVC when ABS will do the same job and not have the risk of injury.

[Chris_Ely]

I found this document from Charlotte Pipe, which is one of the leading pipe manufactures. Throughout the document, there are numerous warnings about using PVC/ABS/CPVC pipe in compressed air applications.

Originally Posted by Charlotte Pipe

Testing with or use of compressed air or gas in PVC / ABS
/ CPVC pipe or fittings can result in explosive failures and
cause severe injury or death.
• NEVER test with or transport/store
compressed air or gas in PVC / ABS / CPVC
pipe or fittings.
• NEVER test PVC / ABS / CPVC pipe or
fittings with compressed air or gas, or air
over water boosters.
• ONLY use PVC / ABS / CPVC pipe or
fittings for water or approved chemicals.
• Refer to warnings in PPFA User Bulletin
4-80 and ASTM D 1785.

On page 82, they specifically mention air cannons.

Originally Posted by Charlotte Pipe

Do not use for SPUD GUNS, FLAMETHROWERS, or
COMPRESSED AIR GUNS. May result in property damage,
injury or death. Use only for fluid handling / plumbing
applications.

Everyone, please heed the manufacture's warnings. Only use materials meant for air pressure.