Choice nuggets from the LDS

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Scuba_Vixen once bubbled...

If you feel how warm a tank gets on the outside after a fill, just figure how hot it got on the surface of the aluminum inside the tank before conduction could spread the heat throughout the rest of the aluminum mass.

Darlene,

Well I figure...

In order to achieve a 400 degree (your value temp at which AL looses tensile strength) difference between the inside and outside you'd need to fill the tank (to 4000 psi) in less then 2 minutes. That's zero to 4000 in less then two minutes.

I highly doubt this happened. The guy filling the tank was clearly a moron but he didn't ruin the tank. If you're really concerned about it make the shop give you a free hydro.

Now you're free to do your own figuring if you want...


Adiabatic heating is not to be underestimated.

I don't think filling a tank is an adiabatic process. There maybe local adiabatic compression in the valves, regs, etc when you open them but in general the whole process of filling a tank is not adiabatic.

Drew
 
Happened in a shop where I get my fills now and then.
I dropped off my tanks (HP Steel) asking for 32% Nitrox and said I’d pick them up in a week.

Week later when I stopped by to pick the tanks up, they were not filled. I was slightly disappointed (first time it happened at this shop), but was not overly surprised, since, judging from my experience, it’s not very unusual.

So the clerk who works there part-time offers me to wait while he fills the tanks. “No problem.” – I said. My expectations for a good service in general, and such in diving industry in particular, are not very high.

In a few minutes he said he could only fill my tanks to 3200#. That I found to be unusual and inquired why.

“What pressure do you want them filled to?” – he asked.
“Service pressure.” – I replied.
“How high is that?”
“3442.”
“No, you don’t understand, that’s what it says on the valve. But these tanks are not to be filled above 3000.”

I know my tanks, I know their service pressure. I’ve had tanks filled at the shop many times. Never had an issue. So I was confident enough to keep on arguing with the guy for another minute or so.

“Alright.”- he said.
“What?” – I was feeling victorious.
“Our 32% Nitrox bank is down to 3200, so I can’t give you a fill above that today…”

It was perfectly OK with me, as long as there was a reasonable explanation…

But do you think it would be a wise idea to take gear advice from this character? I don't think so. That much for buying from an LDS, partucularly, if you do need advice.
 
I'm just amazed ... Maybe we can come up with an IQ test for dive shop employees?
 
Scuba_Vixen once bubbled...

Why not email Luxfer or Catalina and ask them what they think of a tank that's been hot filled to 4000# and left that way....apparently untill it was used

If they say the tank's fine, I'll eat humble pie all month...


I took your suggestion as I was curious what the "experts" would say.
This is a reply from Luxfer customer service with the exact scenario you described:

Dear ---------
Thank you for your inquiry. First of all, the cylinder has been overfilled
which is a definite NO-NO!
We recommend that the cylinder be emptied and hydrotested before using
again. If the cylinder passes hydro, it is safe to be used. Please be
advised that per the DOT 3AL specification, these cylinders are to be filled
to the marked service pressure of 3000 PSI. Do not overfill!

Best Regards,
Pam McLean
Customer Service Manager
Luxfer Gas Cylinders
 
on that one. If they say it's up to the hydro test, as to whether to use it or not, I'd have to go with the experts for sure.

Now what would would really be helpfull, would be for COVCI to chime in here, since that's his business, and he could give us the results of years of experience about overfills and hydros.

Did you get word from the other manufacturer yet, will be intersting to compare what each has to say.


Glad it wasn't one of my tanks,


Darlene


PS: COVCI is the guy at Central Ohio Valley Cylinder Inspection
 
Scuba_Vixen once bubbled...
They sure passed the buck on that one. If they say it's up to the hydro test, as to whether to use it or not, I'd have to go with the experts for sure.

Their answer was entirely appropriate.

Let’s get one thing straight: the manner in which a tank is filled does not provide sufficient information to draw conclusions about the status of the tank.

Luxfer understands this and is why they answered as they did.

Why is this so hard for you to understand?
 
Does that make ya happy now.....

I'd still like to see what would happen at hydro..


Darlene
 
Scuba_Vixen once bubbled...

I'd still like to see what would happen at hydro..
That's kinda been my point all along...
 
Scuba_Vixen once bubbled...
Does that make ya happy now.....

I'd still like to see what would happen at hydro..


Darlene

Actually, they passed hydro and are still in use.

Just call me Mr. Pie..:wink:
 
https://www.shearwater.com/products/perdix-ai/

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