The chemicals in the adhesive of duct tape could also potentially weaken the plastic, I would be wary of this as a solution.
Theoretically, same materials, similar specs. I would suspect we are going to have a response soon. Please be patient. Use the tanks from last year in the meantime.
Indeed they should, but all too often people who don’t understand the science behind a decision are the ones who make it, especially when the government is involved…
I’ll never forget teaching in California when a law was passed (unanimously by both houses and signed into law by Governor Davis) that outlawed “chemicals made from dangerous elements” in science classrooms… Further investigation indicated that “dangerous” included anything “toxic” or “flammable”.
Not withstanding the absurd misunderstanding that toxicology is a matter of dosage (and that even water ingested in sufficient amounts is toxic), the ignorance of even middle school level chemistry was quite astounding.
Among the things unintentionally outlawed in California science classrooms: matches, table salt, water, air, humans.
Although your suggestion of a sock sounds pretty good, what about versions of the mesh bags used to contain onions and other similar vegetables? (Those might be easier to incorporate into existing designs.)
My thoughts around using the sock was that they would be elastic and absorb the energy of an expanding tank while allowing the compressed air to permeate the fabric and release pressure. The onion bag idea could work as well but are they not a relatively non-elastic material?
Would it make it safer to put a wrapping of duct tape around them
I think since the duct tape would be wrapped around the tank tightly it would tear as the tank expanded. I feel it would also contain the compressed gas which could cause it in itself to burst like a balloon.
I’ll just leave this here…
I do not advocate teams reinforcing their plastic tanks.
Though the added weight a reinforcing a plastic tank might make metal tanks weight-effective again. They will certainly be safer.
From the Tristan
“I’m curious about what specific factors are driving your decision—not particularly to criticize you.”
No criticism taken. Here is the reasons for my actions. Another school had an accident a few years ago and we are under a microscope. A failure of one of our tanks after being the alerted to the problem would cause us serious trouble. Our students run our machine shop and welder. I do not want to risk that program. The type of tank is not critical for out prototype and the definitive answer should be out in time for the final robot. While we all manage risks all the time because of our situation this risk is not needed or worth taking.
FYI, here is an email I just received.
Dear FIRST Team Member,
Clippard has been made aware of an incident where the white
polypropylene air tank had burst. There are several factors that
could have led to this and Clippard is evaluating the issue. We have
yet to replicate the occurrence at a pressure below 700 psi, and
believe this to be an isolated occurrence. However, working with
tanks under pressure can lead to dangerous circumstances and
precautions must be taken.Until a full evaluation is complete and in the interest of safety,
Clippard recommends that your team dispose of their current tanks and
replace them with the SS-1154, the 32in3 metal version, at no charge.
To replace your tank, reply to this email and include your team name
and number of tanks to be replaced. We apologize for any
inconvenience and wish you all success in your upcoming competition.Sincerely,
Clippard Instrument Laboratory, Inc.
You really can’t beat that for customer service!
We have at least 8 of the Clippard Tanks…until we know for sure if they’re actually bad, I think that if anything we’ll just ask for the minimum number of replacements that we actually need on robots this season. If they are indeed safe, the weight savings are worth it.
Does someone have the email address to request replacement air tanks from Clippart?
Thanks!
One of our air tank’s was cracked on the “rim” right out of the box. We’re glad we spotted it before we put it on to our robot all thanks to this thread. Thank you, and were glad everyone’s okay!
Spencer,
I bet that the manufacturer will want to know or see that defect.
One legal way to provide some measure of protection of your tanks from external damage, or shrapnel containment would be to use expandable mesh sleeving. This is the stuff usually used for wire bundling, and which also can be used to make pneumatic muscles.
McMaster Carr has it in various colors in a size suitable for slipping your tank inside.
ID range: 1 1/2" to 3 1/2"
Part number: 9284K419
Price: $14.53 for 10 feet.
Todd,
While this product might contain the broken parts, I would not want to mislead people into thinking this a good fix. This mesh is designed for something entirely different.
this picture describes how my team are handling the air cylinders after this tread 
If you have definitive decisions please let us know, we are in Brazil … swap or buy new cylinders would lose more than 2 weeks
Jeser
1772
I know this thread is old news, but I want to caution teams with these tanks still on hand. One of our mentors attempted to install a 90 degree fitting (plastic – from FIRST Choice) on one of our tanks today, he was only able to turn the fitting about 400 degrees before the rib on the port cracked open. It was a hairline crack, hardly even noticeable to the eye, however it extended the entire length of the threads and was about an 1/8" deep. Since he was watching for this to happen, the flaw was discovered before a real problem occurred. Our plan had been to test each tank with shop air (~140psi) prior to use, after seeing how fast these crack we are moving on to other tanks. If you are going to continue using these tanks, please do so with caution.
Yikes! Glad everyone is safe!
Did FIRST include this information in an email blast? I was visiting a team earlier this week and they didn’t know about this issue. They were in the process of setting up a pneumatics breadboard. I showed them the blog post and a bit of pneumatics safety. They decided to plumb everything as training, but were not going to use these tanks in a live system. I am working with a different subgroup when 20 minutes later when one of the pneumatics kids came over with a cracked cylinder. They had followed the blog installation instructions and had put a crack that is vertically the full length of the threading, out through one of the ribs, and about 1 cm down the outside of the tube. They said they probably would not have noticed if I hadn’t pointed out the blog post and they were concerned about doing it correctly and looking at it closely.
The point is that teams still don’t know, and tanks are still having issues.
Wetzel
I haven’t seen a FIRST email blast in two weeks-unusual during build season.
Just the Blog warning.
And a cryptic notice to look at the blog warning, on the KOP Technical Resources webpage.
The email blasts have been going out. I do not recall see a warning about the air cylinders on them though. There are also on first’s web site if anybody wants to look through them.