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Lulubelle
09-29-2009, 07:54
I have two recently purchased HP 100s. One is less than half full, the other one pretty much full (thumbed dive :(). They aren't going to get used for a while and are in my garage. Since they will be sitting there until next summer, is there anything I need to do? Like drain the full one a bit or anything. This is not heated or cooled space but the temperature never gets too extreme in NC or in that garage.

Thanks

L

SkuaSeptember
09-29-2009, 08:20
I have never had a problem with storing full tanks for a couple of months or more, but theoretically if the fill you got had a very high moisture content extreme corrosion could result and the oxidation could deplete the available oxygen resulting in a hypoxic gas mix. Also, maintaining a sustained load on the tank, valves and O-rings can shorten their life span.
Best practice is usually to bleed them down to 100 psi or so and get a fresh fill in the spring.

Lulubelle
09-29-2009, 08:43
I have never had a problem with storing full tanks for a couple of months or more, but theoretically if the fill you got had a very high moisture content extreme corrosion could result and the oxidation could deplete the available oxygen resulting in a hypoxic gas mix. Also, maintaining a sustained load on the tank, valves and O-rings can shorten their life span.
Best practice is usually to bleed them down to 100 psi or so and get a fresh fill in the spring.

Tanks! :smiley20: I had no idea.

Vercingetorix
09-29-2009, 12:06
It's a shame that these tanks will go unused. Tell you what. I'll store them for you. Just ship them to Dallas, Texas. When you're ready to dive again, I'll ship them back. But only IF they are safe for diving, because I don't want to endanger you. I'll run them by ScubaToys, and if Joe declares them unfit (*cough*$50 bribe*cough*), then I'll save you the expense of return shipping and the danger of diving with malfunctioning equipment.

I'm just looking out after ya, darlin'.

Lulubelle
09-29-2009, 12:16
It's a shame that these tanks will go unused. Tell you what. I'll store them for you. Just ship them to Dallas, Texas. When you're ready to dive again, I'll ship them back. But only IF they are safe for diving, because I don't want to endanger you. I'll run them by ScubaToys, and if Joe declares them unfit (*cough*$50 bribe*cough*), then I'll save you the expense of return shipping and the danger of diving with malfunctioning equipment.

I'm just looking out after ya, darlin'.

I'll get right on that V. I just didn't know if I needed to bleed the full one a bit. I figured the mostly empty one would be fine. They are both going to sit for probably 9 months or so.

Hey, I love my new avatar, just channeling my inner introvert today and hiding behind my mask! 110 ft "into the blue" in the Turks and Caicos. I want to be hanging there in the middle of nothing right now.

Scuba Pete
09-29-2009, 13:20
When i first started diving i was using tanks from the 70s that were kept in the basement for 20-25 years full. We got them vis'd and hydro'ed without any problems. One of those tanks was the bad aluminum. I dont think keeping a tank stored for that amount of time full is that bad. During my 3 yr diving hiatus 6 of 7 tanks were stored full. No problems. However, if something were to happen like a fire of something falling on the valves there would be much more of a dramatic situation with full tanks as compared to tanks with 200 or so psi in them.

it_mike
09-29-2009, 14:02
Lulubelle, come drain them at the DUI rally (Lake Rawlings). For $10 you can try out multiple drysuits, and they will give you an 'intro' lesson on how to dive them. They also keep spare fins on hand if your's don't fit the suit.

Oct 24/25

cummings66
09-29-2009, 15:02
I've always kept my steel cylinders full and have never had a problem, but I know my air is good and dry so for what it's worth that's my take on it.

PSI family line is drain them to 50psi for long term storage. I don't consider a couple months long term storage. As to O rings, good practice is to replace them during the visual and it's one that I do to any cylinder I visual myself. Why be sorry? They don't cost much of anything.

CompuDude
09-30-2009, 00:23
Ordinarily I wouldn't bother draining them at all, because you never know, and frankly there's very little chance of any harm to the tank (from the pressure... skua makes a good point about damage from moisture in the case of a wet fill), but if I KNEW I was not going to touch them for a full 9 months, draining them to 100-200 psi is cheap insurance in case of a fire.

emt
09-30-2009, 19:41
Scuba Pete said: However, if something were to happen like a fire of something falling on the valves there would be much more of a dramatic situation with full tanks as compared to tanks with 200 or so psi in them.



During a tank fill over the summer, I was putting the tanks in the van and the gal at the shop said: Make sure the valve is toward you while driving in case someone rams your van in the rear it's heading back toward them....lol. :anim_rocket:
Just wondering if anyone has seen anything like that with full tanks having an immediate rupture?

Splitlip
09-30-2009, 19:45
There are no stupid tanks....

Lulubelle
09-30-2009, 19:59
There are no stupid tanks....

:smilie39:

OK, so I'm easily entertained at the moment.

ReefHound
09-30-2009, 20:55
When i first started diving i was using tanks from the 70s that were kept in the basement for 20-25 years full. We got them vis'd and hydro'ed without any problems. One of those tanks was the bad aluminum. I dont think keeping a tank stored for that amount of time full is that bad. During my 3 yr diving hiatus 6 of 7 tanks were stored full. No problems. However, if something were to happen like a fire of something falling on the valves there would be much more of a dramatic situation with full tanks as compared to tanks with 200 or so psi in them.

Actually, half full tanks are more dangerous in a fire than full tanks. Reason being as the air will expand from the heat. Full tanks will quickly expand to the point of blowing the burst discs before the structural integrity is compromised. Half full tanks may have structural failure before reaching that point.

Splitlip
09-30-2009, 21:07
When i first started diving i was using tanks from the 70s that were kept in the basement for 20-25 years full. We got them vis'd and hydro'ed without any problems. One of those tanks was the bad aluminum. I dont think keeping a tank stored for that amount of time full is that bad. During my 3 yr diving hiatus 6 of 7 tanks were stored full. No problems. However, if something were to happen like a fire of something falling on the valves there would be much more of a dramatic situation with full tanks as compared to tanks with 200 or so psi in them.

Actually, half full tanks are more dangerous in a fire than full tanks. Reason being as the air will expand from the heat. Full tanks will quickly expand to the point of blowing the burst discs before the structural integrity is compromised. Half full tanks may have structural failure before reaching that point.

Reef, the same thing crossed my mind. Is there any evidence to support that though? Catastrophic cylinder failure before the burst disk goes I mean.

Scuba Pete
09-30-2009, 21:45
When i first started diving i was using tanks from the 70s that were kept in the basement for 20-25 years full. We got them vis'd and hydro'ed without any problems. One of those tanks was the bad aluminum. I dont think keeping a tank stored for that amount of time full is that bad. During my 3 yr diving hiatus 6 of 7 tanks were stored full. No problems. However, if something were to happen like a fire of something falling on the valves there would be much more of a dramatic situation with full tanks as compared to tanks with 200 or so psi in them.

Actually, half full tanks are more dangerous in a fire than full tanks. Reason being as the air will expand from the heat. Full tanks will quickly expand to the point of blowing the burst discs before the structural integrity is compromised. Half full tanks may have structural failure before reaching that point.

I wonder if the rise in temperature causing the burst disk to burst then the further increase in temperature causing even more pressure inside the tank, more than the tiny hole that the burst disk can exhaust, will eventually last long enough to structurally damage the tank causing the catastrophic tank rupture would be more likely with full tanks. (I think this may be gibberish, but i think it may get what is in my head on paper) Either way I don't want to be around if it happens.

ReefHound
09-30-2009, 22:07
I think a burst disc will drain a tank in less than a minute.

CompuDude
09-30-2009, 22:55
I think a burst disc will drain a tank in less than a minute.

They'll drain it fast (yay, fan the flames! And just think of the effect of Nitrox!).

Point is, you still want the bursts disc to go before the tank has time to get hot enough to lose structural integrity.

Either way, as Pete noted, you don't want to be anywhere near it.

BubblesMcCoy
10-01-2009, 08:21
Point well taken. Steps to take if house is on fire: put down the scuba tanks, grab the kids, leave. OK got it.

Sorry, just in a bit of a mood.

Daved
10-01-2009, 22:08
Was the tank half Full?

Will you get more moisture if they are drained down--or kept full?

In Bon a few years back there was a a boom! Tank in the back of pick up had value towards cab. Guy hit the brakes hard and tank slid into back of cab.--must have hit on angle--or something.