Overfilling Scuba Cylinders

[meierdierck]

I just love this cave-country quip. "The best part about scuba tanks is that they have the turnaround pressure stamped right on their necks."

rule of 3rds...I get jokes....

 

[Kevin Carlisle]

OMG so hes crazy. Thank you for saving our life. I will no longer dive with those people.. I cant believe they are still alive.

People do all kinds of crazy things and get away with it, but it does not mean it's safe.

Adam

 

[UCFKnightDiver]

People do all kinds of crazy things and get away with it, but it does not mean it's safe.

Adam

For 30-40 years though?

 

[deepn0va]

Are there any documented accidents related to overfilling lp tanks?

 

[OldNSalty]

So is this just lp steel? What about hp steel or Al?

 

[deepn0va]

lets look at all tanks. at what points to the alloys begin to fail, what is technically unsafe (not what is legal) for each type of tank, and what damage will your regulators incur before the tank fails. Are today's regulators safe for use at pressures of 4200psi? 4500psi? 4800psi?

 

[rstofer]

So is this just lp steel? What about hp steel or Al?

Given the horrible reputation of aluminum tanks (back in the days of 6351 alloy), not too many shops will overfill one. OTOH, people with their own compressors can make any mistake they wish.

There have been some posts in the Tanks forum mentioning overfilling HP steel but the overfill is modest. Perhaps a few hundred pounds. I think everyone realizes that the HP steel tanks are designed to a limit. In fact, the hydro test pressue in terms of percent overpressure is lower on a special permit HP tank than it is on a standard tank. Want to guess why that is? See if the tank type is 3AL, 3AA or Exxxxx. The E tanks are special exemption. For whatever reason, they are not manufactured to the standard of either 3AL (aluminum) or 3AA (steel). It might be that all HP tanks are E. I don't know. I do know that my Worthington HP 100 tanks are special exemption.

Interesting side issue: if the manufacturer doesn't renew the special permit and no other group picks it up (and presumably takes on the liability), the tanks are no longer allowed to be filled. I need to think about this. Should I keep buying E tanks? Maybe not...

The typical target of overfilling is the LP tanks.

Richard

 

[rstofer]

lets look at all tanks. at what points to the alloys begin to fail, what is technically unsafe (not what is legal) for each type of tank, and what damage will your regulators incur before the tank fails. Are today's regulators safe for use at pressures of 4200psi? 4500psi? 4800psi?

I have been spending time and money worrying about yokes. My old Oceanic Omega II regs (circa 1988) had a yoke rated for 3000 psi. Now my tanks are 3442 psi. Hm... Time to figure out how to get a yoke rated 3500 psi. Oh, I know! Convert them all to DIN! Worked for me...

To make matters more complex, I have an old DW Mistral double hose reg and it really doesn't want to see anything above about 2400 psi and breaths best at about 1800 psi. I use this with an old LP 72. The Royal Aquamaster is probably good for 3000 psi so I can use it with the LP 72 or the aluminum tanks. The Phoenix converted Aquamaster is ok for 3500 psi.

I have to keep track of which regulator I use with which tank. I really don't want to damage these regs.

Richard

 

[UCFKnightDiver]

regardless din or yoke, you get more wear and tear on a regulator with higher pressures, so the question becomes how high is too high?

 

[tlt]