Chief Delphi - Are these tanks legal?

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Re: Are these tanks legal?

James,
I don't recall that rule. There were times when plastic tanks were not allowed, and there were restrictions on how much storage a robot could contain. Heck, I even remember a time when pneumatics were not allowed.

Re: Are these tanks legal?

Quote:

Originally Posted by Daniel_LaFleur (Post 1541400)

This emphasized statement bothers me ( and this, coming from one whom is distrustful of plastic volumes).

1> Are these items allowed per the rules? Yes.
2> Does a Plastic Volume with threaded ports have an inherent risk? Yes.
3> Should an LRI automatically ban that item? No. (s)he should look at the implementation and decide if enough has been done to mitigate the safety risk and then make a judgment call.

It's the same when you are using sprockets and chain. It is in the design and implementation that makes it safe of not.

First of all, I am not a LRI, just a lowly RI and of course it would be escalated.
Second, there are always tanks available at competitions so replacing a questionable tank is not an undue hardship on the team. A box around the tank is also a safe option.
Third, the blue box on R76 says "Consider pneumatic components sacred". That is stronger language than sprockets and chain. The tank will have a torque specification on the fittings, how does a RI verify that it has never ever been violated?
Last, the push in fitting tanks do have a limited life, but the failure of the fitting results in the tube being expelled in a safe manner.

I personally think the risk of using the tank in question is too high and would not use it even for practice.

Re: Are these tanks legal?

Quote:

Originally Posted by trumpthero786 (Post 1541061)

Hmm I can't imagine using anything BUT the plastic tanks, but you have far more experience than I do. What sorts of failures have you seen in them?

We always use them. Not the white ones, but we had 5 of the black tanks on our robot last year and that robot that went an entire season, plus two off-season events, and numerous outreach activities without a problem. Just check that your wiring is correct, the compressor shutoff switch is fully functional, and you'll never have a probem. (yeah, there's white ones that are perfectly okay, but if you can't tell the difference between a good white tank and a bad white tank, and you still can't tell after doing some research, you're better off just using something else) We still had one of the bad white tanks for quite a while, and we didn't realize we still had it until someone found it in the bottom of a scrap bin last season. After checking its model number on line and realizing it was one of the failure-prone tanks, we got rid of it immediately.

I was at an event where one of those tanks exploded. Fortunately, I wasn't nearby, but that bang could be heard throughout the entire building. Personally, if I had even the slightest feeling that one of the air tanks might be faulty, I probably wouldn't use it purely out of superstition. However, this doesn't mean those tanks are objectively against the rules, and it also doesn't give an RI the ability to fail you unless the tank is actually not legal. However, with such an ambiguous marking, if those tanks were to be used, it would be wise to figure out what they actually are, and ensure that the documentation legitimizing their use is on-hand.

Re: Are these tanks legal?

Quote:

Originally Posted by MrBasse (Post 1541589)

I worked for Parker Hannifin for several years designing products in their brass fittings division and we utilized a large group of their PTC fitting line in our product. I'd have to dig to find it if I still can, but the rating used to be on the product catalog main page. When you insert the tubing, the proper method is to insert fully and they'll tug to seat the barbs. This deform the barbs a little bit. After being done a few times the barbs no long hold a perfect shape. The metal that makes up the barb itself is only a few thousands thick and won't hold shape for long when being deformed back and forth. I'll see if I can find the spec and get back to you.

The orings just get torn up if your tubing isn't cut properly...

I just got off the phone with a Parker Applications Engineer. Consider my mind officially blown. Parker is completely unwilling to stand behind the reliability of connections made with their PTC fittings. They say the fittings are tested to an ISO spec of FIVE make and break connections and are not willing to publish reliability data beyond that test. I work at NASA Langley Research Center as a contractor, and reliability of pneumatic connections is a BIG deal. I now need to make some calls to our pressure systems safety office. This has the potential to turn into a big hairy deal.