exploding plastic storage tanks

[Tom Line]

Does anyone happen to know if the Andy Mark white tank that is sold is Clippard, or Pneuaire?

Can someone confirm that the tanks that exploded are only the Clippard brand 'white' threaded version?

[Jim Wilks]

Is Clippard the only maker of plastic tanks? Are the ones from PneuAire also from Clippard, or does PneuAire make their own?. Anyone else?

Are all of the failures so far on Clippard tanks?

[thefro526]

Not to add another reason to not use (or be wary of) plastic air tanks but, has anyone paid attention to the temperatures they're being exposed to, either while in operation or storage?

The published temperature range for the New (2014) Black AVT-PP-35 Tank is 35* F - 100* F (1.5*C - 37.5*C), and I believe (but don't quote me) that the tanks from previous years have the same or at least similar temperature range.

I can think of a handful of different ways that tanks could be exposed to conditions outside of that window, which makes me wonder if environmental conditions play some role in the tank ruptures...

[Trent B]

Originally Posted by Jim Wilks

Is Clippard the only maker of plastic tanks? Are the ones from PneuAire also from Clippard, or does PneuAire make their own?. Anyone else?

Are all of the failures so far on Clippard tanks?

The PneuAire tanks are distinctly different in design from the Clippard tanks. Unfortunately I don't have a pair handy to take photos of, but I have handled both at the same time this past build season.

[AllenGregoryIV]

Originally Posted by Jim Wilks

Is Clippard the only maker of plastic tanks? Are the ones from PneuAire also from Clippard, or does PneuAire make their own?. Anyone else?

Are all of the failures so far on Clippard tanks?

Before we call for a ban on all the plastic tanks, I think we really need to answer these questions. As far as I know PneuAire made the plastic tanks before Clippard started doing it. It was my understanding that Clippard released the 2013 plastic air tanks in response to teams using the PneuAire ones in the 2012 season.

We have used the PneuAire tanks (bought from PneuAire) without any failures for the past 3 years (only 2 in competition).

Safety is very important but we also shouldn't overreact.

[Mr V]

Personally I'm for a ban of the plastic tanks. It is not that they are inherently unsafe, but that there are so many ways to unintentionally compromise their safety that are likely to occur when used in FRC.

[Mark Sheridan]

Looks like I am gonna have to relocate my air tanks.

Just a crazy idea that is not FIRST legal:
Could we make our own storage system with large OD high pressure tubing and barb fittings?
http://www.mcmaster.com/#5632K43

This stuff is ductile and could be snaked around, cut to length and should not explode when pierced. Has anyone used this stuff at 120 PSI, the most I ever used is 90 PSI, same with barbed fittings. I am not a fan of barbed fittings but I think this could be safer.

The rules would have to change in order for this to happen. Thought? I am not sure this is the ideal tubing, but this is something I used before that sort of works.

[JesseK]

Originally Posted by Mark Sheridan

Looks like I am gonna have to relocate my air tanks.

Just a crazy idea that is not FIRST legal:
Could we make our own storage system with large OD high pressure tubing and barb fittings?
http://www.mcmaster.com/#5632K43

This stuff is ductile and could be snaked around, cut to length and should not explode when pierced. Has anyone used this stuff at 120 PSI, the most I ever used is 90 PSI, same with barbed fittings. I am not a fan of barbed fittings but I think this could be safer.

The rules would have to change in order for this to happen. Thought? I am not sure this is the ideal tubing, but this is something I used before that sort of works.

Cut to length sounds appealing, but "Snaked around" with a 36" bend radius (6' diameter !?) shouldn't be promoted.

[Mark Sheridan]

Originally Posted by JesseK

Cut to length sounds appealing, but "Snaked around" with a 36" bend radius (6' diameter !?) shouldn't be promoted.

Hmmm...I need to go straighten something out, brb

[Gregor]

For anyone who doesn't know, these are the terrifying pieces flying through the air that we're dealing with.

[Racer26]

Originally Posted by Gregor

For anyone who doesn't know, these are the terrifying pieces flying through the air that we're dealing with.

Moving with enough kinetic energy to do lots of damage. Luckily so far, the serious damage has all been to inanimate objects. I agree HQ needs to do something, though I'm not sure an outright ban is necessary.

[Mark Sheridan]

Originally Posted by Gregor

For anyone who doesn't know, these are the terrifying pieces flying through the air that we're dealing with.

"You'll shoot your eye out"

Those are scary. Are the tanks breaking in a localized area or is the whole thing exploding?

[FrankJ]

Originally Posted by Mark Sheridan

"You'll shoot your eye out"

And that is why you wear safety glasses in the pit.

[JamesCH95]

Originally Posted by Tom Line

I STRONGLY disagree that the only avenue of improving the potential safety issues around plastic pneumatics tanks is outlawing them. I would much rather see a numbers-driven problem solving method applied.

However, I can see vendors stepping away from supplying a 'safety' item like a sleeve since it becomes a question of liability if someone gets injured.

You're doing it wrong. The question should not be "how do we make plastic storage tanks safe?" The question should be "how do we make safe, light, air storage tanks?" Because teams only use plastic storage tanks because they are lighter than commonly available metal tanks.

Here are some numbers:

Polypropylene: ~37MPa TS, 0.94g/cc density, 39MPa/(g/cc) strength:density ratio

304 Stainless Steel: 515MPA TS, 8.0g/cc density, 64MPa/(g/cc) strength:density ratio

The reason why teams use plastic tanks is because they are lighter than the stainless tanks from Clippard. Unfortunately, this low weight comes at the price of strength and durability. Stainless steel has a significantly higher strength:weight ratio than polypropylene.

Plastics tend to have brittle failure modes in dynamic situations, which is why they generate shrapnel, and why they are generally a terrible choice for pressurized gas applications. Not to mention their sensitivity to temperatures, certain chemicals, nicks/scratches/gouges, over-tightening, etc.

[JVN]

Have any of these discussed failures been with the new black tanks?