Overpressurizing / Overfilling steel tanks

[Lost Yooper]

Your humor is quite welcomed, Joewr!

I'm not here to convert anybody to anything, but rather to present particular points of view -- which are often against the grain of traditional diving philosophies -- but are generally supported by some form of evidence or (IMO) common sense.

We're all here to learn and to share things, and I believe these type of discussions (if kept civil) are a great way to do it. People can thoroughly evaluate both sides of a topic and choose their own course of action. I like it.

Take care.

Mike

 

[scubatexastony]

it took a good 20 minutes just to scan through the highlights of this post, you guys find time to get in a dive now and then?

tony

 

[large_diver]

Joe -- such words of wisdom.

I have to admit, I kind of like it when things get a little stirred up around here. As the Yooper has wisely stated, we all end up learning learn "stuff" as a result of our little disagreements.

-LD

 

[roakey]

Originally posted by joewr
So I concluded that folks felt personally "threatened" because they had taken a position and could not abide someone challenging that position

I wanted this to end with my apology and an exchange of mail but no, you had to go public.

The only person who felt threatened during this exchange was you, joewr. In your mail to me you said I called you, and I quote, a "liar." I didn't think my statement could be taken that way, especially with the smiley face after it, but because I really do try and not insult people I sucked it up and apologized, because if you felt offended, I obviously wasn’t clear and therefore I owed you an apology.

Judging from the mail I’ve received, seems other folks can’t figure out how it you misunderstood it, either.

No matter, so far, so good. I was a happy camper, end of exchange.

Bu then you come back with “So I concluded that folks felt personally ‘threatened’…” and “Now, I am not a great peace maker…”

What a bunch of crock (yes, that was personal if anyone has any doubt).

*I* made every reasonable effort to maintain peace up to and including a public apology and you just had to take another shot.

I can’t publish your private mail to me because that’s unethical (not to mention that I’ve deleted it because I thought everything was over and done with). But I will never, ever trust you to the point on acting on private mail from you again. There’s nothing I hate more than being taken advantage of.

Gentle readers, I’m really sorry about this, but getting slammed after apologizing publicly exceeded even my capacity to let things slide.

Roak

Ps. I've been noting for over 20 years on various networks and boards, and I have never been driven to this point before. For those of you that know me from other boards, you know this is an exception, for those of you that don't let me assure you this is.

 

[roakey]

Sorry everyone.

Can't add much to that simple statement.

Roak

 

[roakey]

One of joewr's mails asked about how much data is out there on overfilling.

I can't answer that question, I don't believe anyone can accurately, but I can present at least some data that we can get some estimates from. I'm trying to post a picture, we'll see if this works.

This is Extreme Exposure's Nitrox bank. That's 31 storage bottles. I haven't seen anything approaching this kind of setup on either coast for ocean diving. I think we can assume that they fill more than just a couple cylinders per day to justify this level of expense. EE is one of many shops in the greater High Springs and Branford area. Off the top of my head there’s Ginnie, Dive Outpost and Rennecker’s (spelling?) place as well. They all overfill. (All but EE uses old submarine ballast cylinders, we could have a whole discussion about these non-DOT-approved vessels too ).

As a guess during the week when we were getting fills at Ginnie, EE and Dive Outpost, there was constant stream of divers getting their doubles overfilled. And that’s during the week; on the weekend there’s quite a crowd. But a very conservative weekday number would be ten fills. So, ten fills per day over four shops times 365 days a year is call it 15,000 overfills per year. So just over the last five years that’s 75,000 overfills, just in the greater High Springs/Branford area. All without incident. And that’s an estimate for a very small area of Florida. There’s Lloyd Bailey’s just down the road in Gainesville. Brownies I understand has quite a setup too.

I’d be comfortable at estimating that there’s been over 100,000 overfills in Florida in the last five years. Again, all without incident. I’d also like to point out that most technical divers that overfill retire their cylinders from overfilling at either their first or second hydro. So worst case if you have an employed diver doing four cave dives a week, every week, that’s 200 a year or only 2,000 overfills over the self-imposed lifetime of the cylinder. Assuming that in reality they only get out every other weekend, that’s 1,000 fills before retirement, or 1/10 of the number of cycles at 1kpsi (or less, a “typical” overfill on an LP is 3300psi) less pressure than the cylinders were spec’d for.

Contrary to popular opinion we don’t use a cylinder until it blows up. We take very careful care of our cylinders and voluntarily retire them early if we habitually overfill.

Do the design engineers say it’s OK? No they don’t. But there is evidence out there that says that what we’re doing it OK. In fact there’s no evidence to the contrary.

But yes, I realize that there’s no way to prove a negative.

Roak

Ps. OK, let's see if this picture will work...

 

[100days-a-year]

Nice pic Roak, it underscores the facts nicely. My buddy has a similar # dedicated to a mix fill station in his garage. 6x4500psi air, 6x3500psi air, 2-4xo2, and 2xhelium all are standard 270 cuft. Use a Bauer to run the banks, the Haskell, and booster pump. We're used to the "sky is falling"syndrome here. Can't believe tho it was just this year that local shops started checking for old Luxfers and Walter Kiddes. I try to smile and remember "I am a bumblebee" We all know bumblebees can't fly.

 

[Lost Yooper]

Now that's what I call a serious fill station!

Mike

 

[roakey]

Since you appear to be interested in EE’s setup, this is one of the two fill stations that they have. You can see the hoses leading around the corner in the right center of the picture; they’re going to the Nitrox bank previously pictured. One hose leads to the second fill station that’s to the left of the open door.

Pictured are 5 Oxygen bottles (green), 6 Helium bottles (tan) and 2 Argon bottles (brown). Both inside and around the corner of the shed pictured to the far right are literally dozens of more bottles. EE’s two compressors and membrane system are off to the left of the photographer.

You may have wondered why I estimated so low (10) on the number of cylinders overfilled per day. That’s because the vast bulk of their business is stage and deco bottles, which are mostly AL80s -- you can see a few in the picture. The AL80s are never overfilled. Just an interesting tidbit are the three blue stage bottles you see just to the right of the person filling the doubles -- they’re JJ’s 300 foot bottles used in Wakulla.

And on the overfilling discussion…

There are two points that I don’t know if I’ve made in the past discussion.

First, I have no problem with a shop saying, “I don’t overfill.” It’s private enterprise and they can do whatever they want to do and I respect their right to do so. So I hold no malice toward shops that don’t overfill.

Secondly, there are those overfilling opponents and proponents who are both very unlikely to change their minds. This discussion is for the others who are undecided so they can make an informed decision. My only goal is that when someone decides to overfill or not, that the decision was an informed one.

Roak

 

[Whitelightnin]

I would like to find out how much you guys/gals REGULARY over fill your tanks to. Please let me know WHAT tanks (pressure ratings ; steel or alm) you are using.

PLEASE ...NO PREACHING ABOUT OVERFILL DANGERS!!! I know this is done & I feel it is a personal choice. I'll live (or die) with mine.

James