exploding plastic storage tanks

[Steve W]

Originally Posted by Alex Cormier

I hope it's not too drastic. I just placed an order for 6 of those black tanks.

I think black tanks should be OK.

[AllenGregoryIV]

I still think people are grouping the tanks into two categories when in reality there are many more than that. Color is not the only distinguishing factor.

2013 Clippard White Tanks - As far as I know are no longer being sold after the manufacture discovered problems and offered to replace them for free.
Only place I have found a photo is in the 2013 pneumatics manual http://www.usfirst.org/sites/default...sInfo_RevB.pdf Teams have had many issues with these tanks some of which have been posted in this thread.

Pneuaire - http://www.pneuaire.com/reca44cuin.html These have been in use for 3 seasons and as far as I know have not had any problems.

AndyMark- http://www.andymark.com/product-p/am-2479.htm I'm not sure who manfactors these tanks but they look similar to the Pneuaire variety and again I don't know of teams having problems with these tanks.

Clippard 2014 Tank - http://www.andymark.com/product-p/am-2649.htm Uses ress in hose fitting and has had at least one failure but not explosive failure.

It's my understanding that Clippard just started making plastic air tanks for the FRC market in 2013. I never saw them on their website before then. Where Pneuaire has been producing them with a burst pressure rating of 500 psi and an operating rating of 125psi for several years before the FRC community started using them.

This is a safety matter but we need to make sure we are getting the facts right.

[Trent B]

Originally Posted by AllenGregoryIV

Pneuaire - http://www.pneuaire.com/reca44cuin.html These have been in use for 3 seasons and as far as I know have not had any problems.

AndyMark- http://www.andymark.com/product-p/am-2479.htm I'm not sure who manfactors these tanks but they look similar to the Pneuaire variety and again I don't know of teams having problems with these tanks.

This is a safety matter but we need to make sure we are getting the facts right.

While Pneuaire and AndyMark look eerily similar, Pneuaire does not sell a 36 cubic inch tank on their website.

Additionally, somehow the Andymark tank is physically larger (Diameter 2.7" vs ~2.5" and Length 12.1" vs 9.9") than the Pneuaire 44 CI tank, but manages to hold less (36 vs 44 cubic inches). Unfortunately I do not have an Andymark tank to compare physical dimensions, weight, volume etc.

[Jon Stratis]

I agree we need to keep our facts straight. I do wonder though how much of the failures we've seen so far are influenced by usage statistics. For example, which tanks are used the most? Which tanks are used more by knowledgeable, experienced teams versus those used by inexperienced teams? Statistics like that could provide an explanation for why we've seen failures in the white 2013 tanks but not the others:

- The white 2013 tanks have been around longer than the black 2014 tanks
- The white 2013 tanks might be more prevalent in FRC than the Pneuaire tanks, due to their availability on FIRST Choice and AndyMark last year.
- The Pneuaire tanks might be used less by inexperienced teams - 3 years ago it was only a few teams pushing the boundaries that used the plastic tanks, and you would expect those teams to be more knowledgeable and having done more research than the teams that just used what everyone else used.

Obviously, the above statements are made with some big assumptions, and I'm not aware of any collected data to show whether those assumptions are correct or not. But without knowing some of those statistics, I also don't think we can limit our concern only to the white 2013 tanks - if there are orders of magnitude more white 2013 tanks in use than the other options, then our sample size for the others simply might not be big enough.

[Trent B]

I would tend to agree that the Pneuaire tanks were used more extensively by experienced teams which extensively researched alternative lighter options to the conventional metal tanks.

If I had to guess I would say the Clippard tanks were used 5-10x as much if not more. Had I not read threads on the Pneuaire tanks on Chief Delphi when people first started using them I probably wouldn't realize they were a "viable" option.

I would also suspect to market for small tanks such as these is relatively small outside of FRC as compared to large 1L+ metal tanks.

[Paul Copioli]

Originally Posted by AllenGregoryIV

My point is that the PneuAir tanks have been in use on FRC robots longer than the Clippard tanks and I have never (doesn't mean it hasn't happened) heard of one of them failing do to misuse or defect.

^this.

We have also used the pneuaire tanks with absolutely no failure. What would be nice is if anyone has experienced a failure with the pneuaire tanks that they share their results here.

I think we should not over react. We should also make sure tanks are agency approved before they are competition legal.

Paul

[wilful]

I think that people are being too quick to assume that user error is the end of the cause of the failures. I have yet to see someone ask why this user error is occurring.

After pondering this, it does seem to be a design flaw. Likely this design flaw is in the documentation and the lack of safety knowledge. If there is a danger caused by stress from over-tightening the threaded fittings, there should be a sticker around the fitting that warns against over-tightening. The same should be true for any other safety issue with any device.

Also for any COTS device, read the manual before use. While the device may not pose an imitate safety hazard from a user failing to read the manual, reading the manual for the product will increase safety while using the product and prolong the life of the product.

[Mark Sheridan]

Originally Posted by wilful

I think that people are being too quick to assume that user error is the end of the cause of the failures. I have yet to see someone ask why this user error is occurring.

After pondering this, it does seem to be a design flaw. Likely this design flaw is in the documentation and the lack of safety knowledge. If there is a danger caused by stress from over-tightening the threaded fittings, there should be a sticker around the fitting that warns against over-tightening. The same should be true for any other safety issue with any device.

Also for any COTS device, read the manual before use. While the device may not pose an imitate safety hazard from a user failing to read the manual, reading the manual for the product will increase safety while using the product and prolong the life of the product.

In any case we need to gather more info and be careful until we know for sure whats going on.

I am using the 2013 clippard tanks, I thought its failure mode was user error too. Am I mistaken, was there a product defect that lead to its recall?

[wilful]

Originally Posted by Mark Sheridan

I am using the 2013 clippard tanks, I thought its failure mode was user error too. Am I mistaken, was there a product defect that lead to its recall?

I do not believe that there is a mechanical flaw with the design, just a lack of world knowledge which led to improper use.

[team222badbrad]

Originally Posted by wilful

I do not believe that there is a mechanical flaw with the design, just a lack of world knowledge which led to improper use.

Or lack of instruction/documentation included with the product?

[wilful]

Originally Posted by team222badbrad

Or lack of instruction/documentation included with the product?

The only problem with simply including documentation is that likely only one person will read the documentation and some people will think they do not need too. This is especially important with temperature issues and material safety.

[MrBasse]

You don't get safety information provided on a sticker on any other pneumatic components. If I crank a cast iron fitting into a stainless steel tank to far the tank won't hold air anymore, but there is no warning for that. I have yet to buy a cylinder that came with documentation about anything. Everything is online if you want it. Clippard had installation instructions on the product page that specified the torque for fitting to seal the connection. When FIRST posted this:

Clippard recommends using 2-4 layers of Teflon tape and tightening the ¼” NPT fitting to 10-12 inch pounds (do not to exceed 15 inch pounds).

last year they didn't make it up, it came from the instructions Clippard provided.

[tim-tim]

Originally Posted by AllenGregoryIV

...

Pneuaire - http://www.pneuaire.com/reca44cuin.html These have been in use for 3 seasons and as far as I know have not had any problems.

...

I believe this is the 4th season of the Pneuaire tanks. Here is a little evidence.

[AllenGregoryIV]

Originally Posted by tim-tim

I believe this is the 4th season of the Pneuaire tanks. Here is a little evidence.

Thanks, I didn't know that.

[jwfoss]

Has anyone used the air tanks from Robart? I stumbled across them when looking for an alternative lightweight air storage solution.