Consensus on Overfilling Tanks?

[Colliam7]

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A ScubaBoard Staff Message...

Several off topic, personal discussions have been deleted. Please keep the thread focused on the original question, which - in case anyone may have forgotten - is: 'In all seriousness though, what is acceptable to overfill a tank to? . . . Is the reason shops won't over fill due to the liability? . . . Should I be asking for this? Is there a law or something that prevents this? . . . What do you get your tanks filled to? What's the acceptable overfill in cave country?

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[Couv]

It was fun while it lasted.

 

[Szymonj04]

My 2 psi.... Aluminum and Steel are 2 extraordinarily different metals (in terms of how they handle stress). If you have the luxury of a shop that will fill to what you ask, do your own research and make an educated decision on where your risk tolerance lies. I will not over fill an aluminum, full stop. I own old school 72s (2250 working pressure), and prefer to run them at 2800 to 3000. Some run them higher than that. When I made my decisions, I looked up how hydro works, and what it's testing for, along with how the two types of metal react to stress.
My closest shop will only fill them to 2250 (making them effectively 65 CF tanks) due to liability/risk aversion. Their shop, their rules, and I respect that. I have another option a little further, that depends on who is running the fill station... some stop it at 2500, one I had to stop at 3200.
Best of luck
James

The dive shop I go to tends to overfill aluminum tanks all the time. Lucky for me I only dive steel so I dont have a problem with it.

 

[BRT]

The dive shop I go to tends to overfill aluminum tanks all the time. Lucky for me I only dive steel so I dont have a problem with it.

I don't have a problem with it either.

 

[wetb4igetinthewater]

I don't know if I said this earlier in the thread, but I go by the shop twice to fill up the tanks. Yes, I could drop them off, but I find that they won't top off a second time, so why leave my tanks there? It takes me the same amount of time.

Yes, this is a major hassle going twice, but for me it is worth it to have nice fills.

 

[rjack321]

consensus and overfilling are key words in SB threads going back decades!

 

[100days-a-year]

On a now unfollowed FB feed I saw someone claim he had seen regulators " explode " from using overfilled tanks and it was a life threatening risk to dive them as they might do so U/W
Rather than respond, I just left the room and shut the door behind me.
Not someone I would likely enjoy diving around.
I see old steel 72s dove that are older than me that have had many thousands of overfills up to 3200 psi. I don't like being near them being filled but the odds of anything untoward happening are less than being killed by a falling coconut I would imagine.

 

[Bigbella]

While I was visiting a friend, last year in Florida, I did notice that the dive charter we used, out of Jupiter, had been cranking their nitrox fills, to about 276 bar (4000 psi); and that the yokes we were using, since DIN tanks had been unavailable, were only rated to about 241(3500 psi).

I was also carrying an older Suunto SPG as a back-up on one of the rigs; and it pegged -- maxed at 4000 . . .

 

[Bob DBF]

While I was visiting a friend, last year in Florida, I did notice that the dive charter we used, out of Jupiter, had been cranking their nitrox fills, to about 276 bar (4000 psi); and that the yokes we were using, since DIN tanks had been unavailable, were only rated to about 241(3500 psi).

I was also carrying an older Suunto SPG as a back-up on one of the rigs; and it pegged -- maxed at 4000 . . .

Anyone blow the valve/reg o-ring? That was the failure mode for the old ( pre 3000# yokes, some made for the old 1800# service) regs when put on HP tanks. The yoke was thin and could flex and the o-ring would extrude.

The new yokes are made to handle HP tanks so 4000# isn't asking a lot more, and the failure mode is not destructive. I do have an old Sherwood yoke reg that was made around 1980 for 4000# service. Unfortunatly, it was made for older valves and the yoke can't be fit over the new convertible valves.

 

[Bigbella]

Anyone blow the valve/reg o-ring? That was the failure mode for the old ( pre 3000# yokes, some made for the old 1800# service) regs when put on HP tanks. The yoke was thin and could flex and the o-ring would extrude.

Surprisingly enough, there were no issues; but on previous trips, I was told there had been occasional o-ring blow-outs . . .