Overfilling LP Steel Tanks -- How bad is it?

[DA Aquamaster]

Ok, you two aren't getting it.

All I am saying is NO dive professional should EVER give any advice contrary to the Law, Regulations or Standards of their agency.

Giving any person the advice, as a Dive Professional, is WRONG and it's really not debatable. It's a fact. If any Instructor/DM/Ast.Inst is sued or and a complaint filed with their agency, they will be found liable and their agency could revoke their certification. This is a FACT not an opinion!

There is such a thing as a "RIGHT" answer. The "RIGHT" answer is to never overfill your tanks.

I know what I do, others know what they do, this guy can ask his buddy's about what they do, the shop can fill his tanks to 5,000 PSI for all I care.

As an Instructor who can be sued, found guilty and potentially lose my certification for giving anything but the right answer...once again...the ONLY answer a Dive Professional can give IS (sarcastic drum roll please!!)....

You can only fill a tank to the pressure that is stamped on the tank.

No offense but most cave instructors certified by NSS-CDS, NACD, GUE, and maybe even NAUI and TDI, will adhere to the philosophy that the pressure stamped on the tank is the turn pressure and if you show up with 2400 psi in your tanks, they'll tell you to go back and get them filled.

From a cave diver perspective it makes a lot more sense to go in fat on gas than it does to fret over the risks of overfilling a 3AA steel tank. There are all kinds of risks in cave diving and doing it safely is accomplished by identifying the risks through accident analysis and then diving in a manner that prevents similar mistakes and avoids those risks. So far, overfilling tanks has not killed any cave divers so it is pretty far down the priority list when it comes to risk management. That would be why overfills are common in N FL but less common every where else.

So let's separate Cave diviing instructors from the OW professionals you are tlaking abiout - who also tend to get themselves killed in caves on a regular basis.

 

[tc]

No offense but most cave instructors certified by NSS-CDS, NACD, GUE, and maybe even NAUI and TDI, will adhere to the philosophy that the pressure stamped on the tank is the turn pressure and if you show up with 2400 psi in your tanks, they'll tell you to go back and get them filled.

From a cave diver perspective it makes a lot more sense to go in fat on gas than it does to fret over the risks of overfilling a 3AA steel tank. There are all kinds of risks in cave diving and doing it safely is accomplished by identifying the risks through accident analysis and then diving in a manner that prevents similar mistakes and avoids those risks. So far, overfilling tanks has not killed any cave divers so it is pretty far down the priority list when it comes to risk management. That would be why overfills are common in N FL but less common every where else.

So let's separate Cave diviing instructors from the OW professionals you are tlaking abiout - who also tend to get themselves killed in caves on a regular basis.

I'd like to see the section in the standards of any of the mentioned agencies that covers that.

Not a caver so I won't dispute that it's common practice, but if anything ever happened they would be pretty much on their own in court.

 

[halocline]

Any answer that isn't a NO is a wrong answer.

I'm disappointed to see Dive Masters, Asstinant Instructors and Instructors advising someone that's ok to over pressurize a tank.

DOT Regs are very specific and can only be filled to the operating pressure stamped on the tank - period - no exceptions.

Giving advice to the contrary exposes one's self to liability, not to mention most likely a violation of your own certifying agency standards.

Any question can be answered based on "experience" or the "Right Answer"....sometimes these answers differ.

The "right" answer is: You should never overfill your tank.

Oh Boy......

If dive instructors were truly liable for every bit of "wrong" advice they gave, there would be nobody to teach diving because practically every one would be tied up in court.

How arrogant to think that you as a "dive professional" can ALWAYS give the one "RIGHT" answer.

 

[SharkDiver36]

Oh Boy......

How arrogant to think that you as a "dive professional" can ALWAYS give the one "RIGHT" answer.

I never claimed to always be able to give the right answer.

If someone asks me a question and I don't know, I say I don't know.

It's no different than walking up to a Policeman in uniform and point blank asking - "Officer can I go 60mph in a 50mph zone?".

The policeman will give you the "right" answer - No.

Re-read the post's I made, it's not arrogance, and no one has all the answers, especially me.

I do know the answer to this question though, and you should too. It was taught in Open Water for me years ago when VIP's, Hydro and the other stamps were explained to me more than a decade ago.

Make sure your advice doesn't conflict with standards or the Law.

 

[H2Andy]

I never claimed to always be able to give the right answer.

oh ...

Any answer that isn't a NO is a wrong answer....

[SNIP]

...The "right" answer is: You should never overfill your tank.

i see

 

[RAWalker]

We are forgetting something here...
Every tank is required to be brought to well over it's service pressure once every five years for hydrostatic testing. This is required by DOT to keep the tank in service. What are the pressures during hydrotest? Yes this is done under controlled conditions by trained personel. But the point is that pressures of a overfilled LP cylinder are substancially less and the safety at those pressures are substancially greater. Granted not as safe as HP cylinders that are rated for higher pressures to begin with.

 

[AceszHigh]

I never claimed to always be able to give the right answer.

If someone asks me a question and I don't know, I say I don't know.

It's no different than walking up to a Policeman in uniform and point blank asking - "Officer can I go 60mph in a 50mph zone?".

The policeman will give you the "right" answer - No.

Re-read the post's I made, it's not arrogance, and no one has all the answers, especially me.

I do know the answer to this question though, and you should too. It was taught in Open Water for me years ago when VIP's, Hydro and the other stamps were explained to me more than a decade ago.

Make sure your advice doesn't conflict with standards or the Law.

I completely understand where you're coming from, but we're not on the same page.
I know the "right/politically correct/answer instructor should give/answer that follows the law/ad infinitum" answer is to not fill above pressures stamped on the tank.

Of course a police officer will tell you its not ok to speed.
However, that wasn't my question.
My question was how dangerous is it? Is it dangerous BECAUSE it's against the law? Not necessarily. Maybe so, but that's not really a good answer in my opinion.
If see stories of these tanks exploding, failing at depth, causing injury due to being overfilled...then that is a MUCH more practical answer to my question. I wasn't asking for logistics & law, I'm asking about overfilling for practical purposes.
And so far..the general consensus based on others EXPERIENCE, seems to be that its a relatively safe practice.
Am I going to consider buying an HP tank after reading these helpful responses? Yes,
actually moreso than before, especially now that I know there's a way to make them compatible with Yoke 1st stages.


I appreciate your input, but I just wanted to make it clear that I understand your point and that isn't what I was asking.

 

[Gombessa]

I'd like to see the section in the standards of any of the mentioned agencies that covers that.

I don't know if it's in the standards, but I do remember that GUE Fundies class materials refer to LP tanks at 3500+psi and even use them as examples in exercises. I trust it's a pretty well-established point.

 

[SparticleBrane]

I note a few posts in here talking about not overfilling steel 72s -- they are made to the same safety standards as other 3AA steel cylinders, and the wall thicknesses aren't too different. Theoretically they should be able to withstand an overfill %-wise the same as other 3AA cylinders.

Personally I try to not overfill my steel 72s very often, as they are not made anymore and I absolutely want to guarantee they'll pass hydro. ~2700-2800psi is the max they'll see. 3000+ is regular in some places. Normally I fill to 2500psi.

I read a cave accident report while back where the guy was diving side-mount steel 72s that he apparently regularly overfilled to 6,500psi.



I also note that the discussion has centered around steel LP cylinders. I will add that aluminum cylinders have to pass the same standards for 'toughness' (for lack of a better term) before they are allowed to go onto the market -- withstanding 10,000 hydro cycles in a 24-hour period (if I remember correctly) before self-destructing. I have had my double Al80s filled to 3600psi for dives before (and they were at 4k when I took them out of my trunk...really hot day :shocked2 I also have a friend who bought a set of double Al80s filled with 18/45, at 4k and had been there for awhile...

As with steel 72s, I avoid overfilling my aluminum cylinders to the point of craziness mainly for longevity reasons -- 3200-3300 is my max if I need a few extra cubic feet, but normally I stay within the service pressure. Since Luxfer is no longer in the scuba market I'd like my cylinders to last as long as possible.


I suppose I will sum up what I am saying with this -- the danger of overfilling well-maintained LP cylinders (free from rust/pitting/dents etc) is pretty small, as shown by the constant repetitive overfilling in cave country, even on some nasty-looking cylinders.

However, with my own personal cylinders, I only overfill when needed. I'm not made of money and I'd like my cylinders to last as long as possible. If I'm doing practice dives in the quarry where our max dive time might be 45mins-1hr at 40ft, do I really need to overfill my cylinders? No, that's just putting unnecessary strain on them. I'll only overfill for longer offshore dives (and even then I won't overfill to cave-country standards!) or if I'm cave diving.

 

[Cave Bum]

I've never been one to mix words.

The Department of Transportation sets the rules and regulations for scuba cylinders.

NO!

The DOT sets regulations for scuba cylinders being transported on public highways. There is NO federal regulation of scuba diving or the equipment used therein (and I hope there never will be...).