Overpressurizing / Overfilling steel tanks

[Northeastwrecks]

Hello,

Seems to me that those diver who overfills tanks are a bunch of self centered tightwads who are to cheap to buy proper gear, push the limits and dive recklessly.

Ed

And this is based upon your vast experience in technical and deep water diving, right?

I fail to see how dual 104's, stages, Apeks regs, drysuit and the rest of my rig could be contrued as "Cheap" or as anything other than "proper gear".

Then again, if I want to know what color is best for my fins, I'll PM you.

 

[GDI]

:doctor:

"The reg is only set up for optimal performance at 300 bar.

300 Bar = 4,410 PSI.

When I say I overfill my tanks, I'm sure as heck not filling them to 4,400 psi.

Well Boogie711 I believe that I have cornered you. You see A reg is not set up to work at a optimal pressure of 300 bar. That rating is there for same reason the tanks have a max working pressure. The optimal working pressure for a reg is actually much lower keyword OPTIMAL. Overfilling your cylinder puts the reg at a risk of failure. And if you filled your cylinders based on what the Europeans do then you would be filling them up to 4500 psi. Since most regs are made in Europe they are rated for the 300 bar service But that does not mean they perform at their max peak performance at that pressure. Your car can move @ 7000 rpm but do you drive it in that range. The CE specs for cylinders and regs is different in Europe than North America and the DOT or whoever rates fill pressures has the historical and imperical data as to why they do it that way. There have been accidents from overfilling tanks both out of the water and during the dive. In case you are wondering the safety standards agencies in Europe report higher accidents/incidents in European industry then the similar agecies in North America. Oh yes they are ahead of us in engineering quality but at what cost to safety. ( larger European companies have excellent safety records, it's the small ones that do not - as a note)

 

[DeepScuba]

heheh

I was content to leave that one alone NE

One look at all my gear, training cost etc tells me the last thing I am is cheap!

I'm still looking at the self-centered, egotistical thing. I think he's right there

Our "guys" do. We always have. It's just how we do it. We either skim on the thirds, or cut back on the B/Time. If we don't want to do either, we "top" the tanks up. After all, it's only "Overfilled" for a very brief time. Remember the fill cycles I spoke of earlier?

There's a point where I will fill mine to, and then that's it. Several guys do more, and I walk away because I personally have a limit, and theirs is higher.

 

[Boogie711]

Pardon? You haven't cornered anyone, GDI. You're spinning this one around so fast it's comical.

You said But since we are looking at what overfilling a tank does and the risk involved what about looking at what your reg is doing when that cylinder is overpressurized. The reg is only set up for optimal performance at 300 bar.

Well, optimal means "Most favorable or desirable; optimum." It hardly means "maximum rated pressure for adequate performance."

And secondly, DeepScuba asked a question you haven't answered yet - how is a Catalina Neutral 80 filled to 3300 psi causing less wear and tear on my reg than my LP95 which is filled to 3000 psi? This thread is, afterall, about overfilling steel tanks.

 

[DeepScuba]

GDI:

So what's the "sweet spot" for you regs as far as HP is concerned?

How long is yor tank at that specific pressure/range?

Beyond that, what does it matter?

How long is his reg working at this supposed "higher than should be" pressure?

How do Florida cave divers "do it"?

 

[Boogie711]

And while we're at it - "There have been accidents from overfilling tanks both out of the water and during the dive."

Please list for me a documented example of an in-water dive accident that's attributable to an over-pressurized tank.

GDI - I'm not trying to be a prick here, but I'll call BS when I see it.

 

[DeepScuba]

Boogie:

hehheh, I think his arguement has sprung more leaks than our LP steels at 3300 PSI!!!

Anyways, guys. it's been nice.

One more grenade......

Is defeating the O/P disk crazy, or does it eliminate a potential failure point. Do the Europeans have burst disks??

 

[GDI]

GDI:

Let me ask you how my regs will work with a 3000PSI ALU80 fill but not with a 3000 - 3200PSI overfill on my LP104's?

Sound silly to you now?

Good question No it does not sound silly, and I hope I can explain this correctly. Otherwise I can't prove my point.
The regs don't know what tank you are using. From that stand point you could overfill a lp 104 to 3000 psi (207 bar, lp 104 is rated for 182 Bar) and the reg should work fine (3200 psi is only 220 Bar). Keep in mind though that that is only a 360 psi overfill (additional 25 Bar , still well short of the 300 Bar service rating, you are still within optimal range of performance) (looking at it from the 2640 psi hydro + fill rating). The issue comes from the same way that they rate a tank fill pressure and consider the compression forces internal to the tank. The tank is not made any different on the assembly line wether it is sold in North America or Europe. the same quality standards will be applied at the manufacturing level. Considering the internal forces add to that the basic physics of a gas as a diver descends. The tank does not so much sense this denser gas but the reg will attempt to compensate for it. This is why some regs do not perform well at depth as others do. Also most of the damage to the seat or failure risk potential will occur at the point you first charge up the reg. At a higher force plus the additional conduit effect, the amount of air getting pushed through a small hole of a valve, the tank will have a higher than normal rated pressure striking the seat when first charged, this weakens the reg seat making it subject to failure and decreased performance. From the tanks point of view we need to look at the internal measurments, thickness of the walls, etc. When you have a balloon and you stretch it the walls get thinner a full balloon will break easier than a soft balloon. You think that steel is any different? No it's not although it's not so obvious. When you overfill a tank or when you do any fill you are streching the tank walls (thats what a hydro test is only more extreme). If the tank has any manufacturing flaws even those which are considered acceptable within tolerance, these flaws will produce weak areas in the walls or threads of a cylinder (most failures of a tank occur at or near the threads) overfilling further weakens the those areas and that is the risk area. Problem is that some divers fill their tanks past the 300 Bar service rating of the reg and the hydro fill test pressure, usually at better than 5/3 the rated working pressure. And you think there is no danger here...
Did I explain this OK?

 

[Genesis]

One more grenade......

Is defeating the O/P disk crazy, or does it eliminate a potential failure point. Do the Europeans have burst disks??

OP disks are there for firefighter protection. Not for your protection.

Defeat them and have a fire at your house where a firefighter dies due to a tank exploding, and you could find yourself on the wrong end of a manslaughter charge and a wrongful death lawsuit.

I consider them a potential failure point, but I've never seen one let go underwater. I have seen one let go while being filled, however.

 

[DeepScuba]

Me too. It's kinda scary isn't it?

SO how hot before it reaches the point in which it will "pop".

Is it going to get that hot in a fire?

Do the Europeans have them?