Consensus on Overfilling Tanks?

[grf88]

I've always believed that any good discussion enjoys a good argument...

Your argument is to argue white dog black and then argue it white again...

Assuming you've taken a cylinder servicing course...what part of ''never over-pressurize a cylinder'' are you having a hard time understanding...if you still have you're course outlines...maybe you need to refresh your memory...

Proceed as you see fit...you don't need me...argue as much as you like...

And people call me boring...

W...

By the same rationale do you suggest releasing pressure from the cylinders when they are sitting in the sun on a dive boat or in a hot car on a summers day because those situations would over-pressurize a cylinder. I think some people would have a different word rather than boring.

 

[Edward3c]

In the U.K. an operator filling a cylinder at a dive shop is at work. The HSE rules are such that filling a cylinder past its working pressure isn’t in line with regulations, the shop risks prosecution.

That said a number of shops do overfill, accepting the risk.

 

[rob.mwpropane]

You know what I think is crazy? There are tank fill safety boxes that protect everything in the area if there's a rupture during fill. We had one at the local aquarium's fill station and beyond taking a little time/space to hook up it wasn't hard to use. If some shops are so freaked about fill safety and spending inordinate amounts of time filling slowly then why the heck don't they have a safety box? It always makes me scratch my head when I think about it. Sure the boxes aren't free but if you've gone to the expense of setting up a shop fill station then it's a drop in the financial bucket and takes very little space.

This russian model is quite a bit larger and more elaborate than the one at the local aquarium. They're a production item for some manufacturers (i.e. not custom made)...

Edit: this looks very similar to what I've used. $4359.00 new.

View attachment 579171
Stationary Containment Fill Stations

Here's one that recently sold for $700 used 1 Containment Fill Station for filling SCBA Bottles. - govdeals.com

Pretty amazing video. I didn't know that the blast chambers are reusable afterwards. At least the video made it look that way.

 

[tbone1004]

I've always believed that any good discussion enjoys a good argument...

Your argument is to argue white dog black and then argue it white again...

Assuming you've taken a cylinder servicing course...what part of ''never over-pressurize a cylinder'' are you having a hard time understanding...if you still have you're course outlines...maybe you need to refresh your memory...

Proceed as you see fit...you don't need me...argue as much as you like...

And people call me boring...

W...

ahh, but does overfilling a tank count as overfilling if it's hot out? Conversely, filling a tank to working pressure if it's really cold out is equally bad. Filling a 3000psi tank to 3000psi at 50F is overfilling the tank, but filling to 3000psi at 90F is underfilling because once they balance out at 68F *the US standard for temperature*, then they won't be at their working pressure.

 

[kelemvor]

Pretty amazing video. I didn't know that the blast chambers are reusable afterwards. At least the video made it look that way.

I was lead to believe (at that aquarium) that the chambers were re-usable. However, I've never actually seen that put to the test. I bet the manufacturer would say no -how else will they keep selling chambers? You aren't likely to have a more dedicated customer than the one that just survived a rupture due to your chamber. So from that perspective I bet customers don't balk much at replacing a used one.

 

[MichaelMc]

The specs call out two pressures. One the stamped pressure at reference temperature. Two an adjustment for a warmer temperature. That adjustment is greater than what is needed from the gas laws by a fair margin. You can hit either constraint per the spec. So filling a tank to the warm temp constraint is in spec, even if it cools to higher than the ref temperature constraint point. That is the spec. Details in an earlier thread, when I dug this up. I dug this up with respect to LP tanks, which add a bit more language.

Now, that is more complex than ‘never above stamped’ or ‘never cool above stamped’. But those are not the spec, from my careful reading of the specs several interlocking paragraphs. If you had to cool never above stamped (or +10%), that is hard to hit and have a customer happy about their fill. But never cool (at reference temp) above stamped (or +10%) is not the spec. If you disagree, site the spec.

To the OP, I think a print out of the spec paragraphs, in that earlier thread, and a graph of those two constraints could help you. Either constraint can be met. Now, that may not be how the shop was trained. Or the additional rules they may want to follow.

EDIT to FIX: I miss-remembered the spec. I crossed out what I think is wrong. See later posts. It was a careful reading at the time, but crappy recall.

 

[tbone1004]

some information particularly pertaining to the PST 3500psi bottles because that's the permit I'm reading.

At a rate not to exceed 200psi/second, the cylinder must not burst prior to 2.25x the service pressure, in this case 7875PSI
The bottles must withstand at least 10,000 cycles to 1.5x service pressure at a rate not to exceed 10 cycles/min *i.e. 10,000 hydro cycles and must still pass hydrostatic testing, and they are cycling from somewhere below 500psi.

Important to note that they are rated for 10,000 hydro cycles, at rapid cycling speeds and must still pass hydro. Not many bottles will ever get filled that many times. That is the logic with the overfilling of bottles in cave country.

Note the 3aa and 3al standards are no more lenient. Aluminum has some metallurgical stuff going on that makes it a worse idea which is why we don't overfill those more than 10%, but still.

 

[rob.mwpropane]

The specs call out two pressures. One the stamped pressure at reference temperature. Two an adjustment for a warmer temperature. That adjustment is greater than what is needed from the gas laws by a fair margin. You can hit either constraint per the spec. So filling a tank to the warm temp constraint is in spec, even if it cools to higher than the ref temperature constraint point. That is the spec. Details in an earlier thread, when I dug this up. I dug this up with respect to LP tanks, which add a bit more language.

Now, that is more complex than never above stamped or never cool above stamped. But those are not the spec. From my careful reading of the spec. If you had to cool never above stamped (or +10%), that is had to hit. But never cool (at reference temp) above stamped is not the spec. If you disagree, site the spec.

To the OP, I think a print out of the spec paragraphs, in that earlier thread, and a graph of those two constraints could help you. Either constraint can be met. Now, that may not be how the shop was trained. Or the additional rules they may want to follow.

Do you have a link? I would like to read if it's not too much trouble.

some information particularly pertaining to the PST 3500psi bottles because that's the permit I'm reading.

At a rate not to exceed 200psi/second, the cylinder must not burst prior to 2.25x the service pressure, in this case 7875PSI
The bottles must withstand at least 10,000 cycles to 1.5x service pressure at a rate not to exceed 10 cycles/min *i.e. 10,000 hydro cycles and must still pass hydrostatic testing, and they are cycling from somewhere below 500psi.

Important to note that they are rated for 10,000 hydro cycles, at rapid cycling speeds and must still pass hydro. Not many bottles will ever get filled that many times. That is the logic with the overfilling of bottles in cave country.

Note the 3aa and 3al standards are no more lenient. Aluminum has some metallurgical stuff going on that makes it a worse idea which is why we don't overfill those more than 10%, but still.

Good stuff to read. Now the idea of why cave country overfills makes sense. I knew there had to be a logical reason somewhere.

 

[MichaelMc]

Do you have a link? I would like to read if it's not too much trouble.

I can’t dig it up now. In an earlier thread on over fills LP tanks etc. I list it in detail. Searching for that should find it and give you more discussion. Quoting here would help others if you find it.

 

[tbone1004]

Do you have a link? I would like to read if it's not too much trouble.



Good stuff to read. Now the idea of why cave country overfills makes sense. I knew there had to be a logical reason somewhere.

it's not THAT much of the wild wild west down there