30 replies to this topic

[Walter]

you have a full tank in your house and have the misfortune of a house fire. You could wreck some fireman's whole day.

Not a problem with steel, but with aluminum, it's a serious concern. The burst disk will go long before there's a problem with pressure in steel tanks. OTOH, heat will weaken aluminum to the point your tanks could fail before the disks go.

if you have tanks with full pressure at the end of the season....

There's a season?

[Diverbrian]

Last time that I checked, we don't do much diving up here from about Dec. to March (something about that solid stuff along the top of the water) and there wasn't much diving in Florida going on during hurricane season last year. So YES!, there is a season in most areas.

Actually, I keep full tanks all of the time. The only catch that I ever have is that I have to analyze them after so long to verify my tag from the last fill as I don't trust my safety to mistaking a EAN32 for a EAN36 tank (faded pen and all on tags).

[Geek]

Not a problem with steel, but with aluminum, it's a serious concern. The burst disk will go long before there's a problem with pressure in steel tanks. OTOH, heat will weaken aluminum to the point your tanks could fail before the disks go.

Even if the burst disk goes, instead of the cylinder acting like a bomb you are spraying 3000 psi, or more, air, or worse Nitrox, into a fire. Not good.

Re: seasons. In your situation, I don't think you have to worry about long term storage of tanks! :-)

[Walter]

there wasn't much diving in Florida going on during hurricane season last year.

I hadn't thought of that, I only made 84 dives during this past hurricane season. OK, so 1 of them was in North Carolina and 15 were in Bonaire, but the rest were all in Florida.

[Cold_H2O]

Walter,
Some of us live where there is NO SEASON. Here in the beautiful and always mild PNW we dive 365 days a year (if only I could figure out how to dive everyday). Water temp does not vary much (56 or so) but spring is known for some of the worse vis due to plankton blooms. Nov - Feb is know for some of the best diving. If you don't dive dry you worry about the cold.

[Walter]

Last time that I checked, we don't do much diving up here from about Dec. to March (something about that solid stuff along the top of the water)

Isn't that why chain saws were invented?

[Diverbrian]

Last time that I checked, we don't do much diving up here from about Dec. to March (something about that solid stuff along the top of the water)

Isn't that why chain saws were invented?

I don't own one. That is my overtime season to pay for my dive season, LOL!

[intotheblue]

Simply put, No electrolyte, OR no Oxygen is NO rust.  Every wonder why nothing rust in dry climates?  Scuba air is VERY dry and unless there is an intrusion of damp air or water or other electrolyte into the tank there will be no rust.  The pressure inside a tank will keep the water out.

As for storing 3000 psig air in a tank for long periods, I don't think it's a good idea from a safety issue.  As for the material science, the design of steel tanks doesn't care and doesn't experience any degrdation over time under stress.  (We don't loosen bolts on our car tires to give them a rest, do we?)  Steel has an infinate cycle life under non-yeild loading as experienced in scuba tanks.  With aluminum it's a bit different as there is no infinate cycle life.  Given enough cycles aluminum will eventually fail, but we're talking millions with tanks.  Still with aluminum it's the cycles, not the duration that causes failure.  (With the possible exception of Luxfers 6351 aluminum alloy which was occasionally prone to very slow crack probagation over time whil under stress.)

Very interesting post. In practicality, I know of cave explorations where stage bottles (usually Al 80's) have been left in systems for many months when a setup was undertaken and subsequent conditions prevented them for being used for that period of time. The tanks are charactristically "cave filled", yet I've seen no incidents reported of problems using them after conditions improved. Please note that cave divers usually are careful to have clean cylinders as they frequently introduce Oxygen into the cylinders in high concentration during partial pressure blending. A clean cylinder with clean, dry gas inside will solve the "electrolyte" part of the equation.... of course all air/nitrox/trimix fills have oxygen inside at high partial pressures.

I have to go "rest my studs" now... catch you later...

ITB

[RichardB]

Simply put, No electrolyte, OR no Oxygen is NO rust.  Every wonder why nothing rust in dry climates?  Scuba air is VERY dry and unless there is an intrusion of damp air or water or other electrolyte into the tank there will be no rust.  The pressure inside a tank will keep the water out.

As for storing 3000 psig air in a tank for long periods, I don't think it's a good idea from a safety issue.  As for the material science, the design of steel tanks doesn't care and doesn't experience any degrdation over time under stress.  (We don't loosen bolts on our car tires to give them a rest, do we?)  Steel has an infinate cycle life under non-yeild loading as experienced in scuba tanks.  With aluminum it's a bit different as there is no infinate cycle life.  Given enough cycles aluminum will eventually fail, but we're talking millions with tanks.  Still with aluminum it's the cycles, not the duration that causes failure.  (With the possible exception of Luxfers 6351 aluminum alloy which was occasionally prone to very slow crack probagation over time whil under stress.)

Very interesting post. In practicality, I know of cave explorations where stage bottles (usually Al 80's) have been left in systems for many months when a setup was undertaken and subsequent conditions prevented them for being used for that period of time. The tanks are charactristically "cave filled", yet I've seen no incidents reported of problems using them after conditions improved. Please note that cave divers usually are careful to have clean cylinders as they frequently introduce Oxygen into the cylinders in high concentration during partial pressure blending. A clean cylinder with clean, dry gas inside will solve the "electrolyte" part of the equation.... of course all air/nitrox/trimix fills have oxygen inside at high partial pressures.

I have to go "rest my studs" now... catch you later...

ITB

ITB,

I should have clarified myself. The safety concerns are those associated with the things falling over, getting dropped, having the valves knocked off and etc. I'm not aware of any health issues with using old air.

RB

[idive2]

No fair! I just checked my email & don't have that one....

marvel, it's on the back of this months florida scuba news, certainly you got
that ! jill, seven fills in seven years, that tank has been deprived !

Kevin

[intotheblue]

I'm not aware of any health issues with using old air.

RB

Actually, I have heard of someone reported in the news, albeit many years ago now, that died diving with a cylinder that had been stored a long time. Memory serves me that the cylinder was an old steel 72 that had been stored for many years. An unsuspecting neighbor, I believe it was, acquired the cylinder and was diving in a local "tank" (pond) of some kind. He didn't surface... and when recovered was found that the cylinder had significant rust inside, and apparently enough moisture to create it... and not enough O2 to support his life. Never heard a follow up on the story, so the death mayhave been caused by something else... but THAT WAS the story.

OAN, please everyone... clearly marking and checking cylinders is extremely important. A good friend of mine died because he didn't read carefully the contents of his cylinder after a long lay-off from diving and didn't check it at the dive site. A tragic and deadly boo boo. Check your gas markings and then the contents with analyzers to verify.

Also, beware that CO poisoning does happen, although not as frequently as it did years ago. Get your gas from reputable sources. If you smell any "off" odors in your air, don't use it. (of course you have to smell it before you put your reg on it to check it, and CO by itself doesn't have an odor... but other contaminants may be present with the CO that do have an odor)

G'nite all...

ITB...

[steelemagnolia6]

There's a dive season??? YOu all know that I hate it when I am the last one to find these things out....

[BradfordNC]

and there wasn't much diving in Florida going on during hurricane season last year.

i spent most of the hurricane season diving in Florida.
the hurricanes didn't have much effect on the cave systems.

[Diverbrian]

and there wasn't much diving in Florida going on during hurricane season last year.

i spent most of the hurricane season diving in Florida.
the hurricanes didn't have much effect on the cave systems.

I thought of that segment because one of my best friends lives in the Ft. Lauderdale area and she was complaining for about 2 months that the diving wasn't happening due to the wind conditions.

I didn't think of cave diving. My tech instructor suggested that I go down there next Feb. to learn to cave dive. I am still wondering if I want to spent a week in paradise getting my butt kicked to learn a type of diving that I have to drive clear down to Florida to do.

[RichardB]

.................My tech instructor suggested that I go down there next Feb. to learn to cave dive. I am still wondering if I want to spent a week in paradise getting my butt kicked to learn a type of diving that I have to drive clear down to Florida to do.

Do a long weekend course. Take the cavern and intro to cave back to back. They are two days each and flow nicely into one another.

Lloyd Bailey has some classes scheduled. Here's a Link.