What’s Wrong With Storing Full Cylinders?

Question asked by Willem Tahon

I have a question about long term storage of tanks between diving seasons. I've read that it's best not to store them all empty but also not all the way full. Seems that anywhere between 100 to 500 psi is recommended. What is wrong about storing them for say 6 months at 3000 psi? Why is this not recommended and what is your opinion about this? Thanks!

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Dreoni
Dreoni
1 year ago

#AskMark Hi Mark! I got a mystery for you. I was diving properly weighted in the morning dive but then on the next dive I needed 2 extra Kgs and I was still a bit floaty at the end with a fully deflated bcd. In the 2h between the dives I ate, went to the WC and my semidry dried a bit. The tank was the same capacity but a different one (both 15L steel). I ended both dives at 50bar. I had a bit of water in my BCD. My buddy did not change its weight and was fine . So It’s something to do with me/my equipment. I counted the lead afterwards and indeed I had 2 extra Kgs. I asked around the dive shop and I got: water in my bc, different tank weights or air pocket in my semidry. Any other ideas on what could have made such a drastic difference?

Scuba Diver Magazine
Scuba Diver Magazine
Reply to  Dreoni
1 year ago

My mind goes to: wearing the wrong weightbelt/pouches and trapped air.
If you dive a similar weightbelt or integrated pouches as another diver it can be easy to pick up the wrong one.
Trapped air could be the issue, and in a semi-dry it’s more likely to trap an air pocket inside compared to a wetsuit.
I’ve never had my buoyancy change after a meal but, I suppose it could be plausible. That and some trapped air could be enough to make you more buoyant

Dreoni
Dreoni
Reply to  Dreoni
1 year ago

@Scuba Diver Magazine Yeah, I think its trapped air plus different tanks (I read that there can be 4 pounds of buoyancy difference between steel tanks (Example: Faber LP95 7 pounds negative vs Faber FX117 11 pounds negative)

Nick Havard
Nick Havard
1 year ago

The correct answer is that there is no such thing as a diving off season so use them all year round and there’s no problem……🤣🤣🤣🤣

P-Ang
P-Ang
1 year ago

#askmark Hi Mark, why are wetsuits mostly black? Why don’t manufacturers produce more colourful designs? It would be so much easier to tell divers apart underwater if everyone is wearing different coloured wetsuits. Are there advantages for wetsuits being black?

Scuba Diver Magazine
Scuba Diver Magazine
Reply to  P-Ang
1 year ago

There are a few reasons. Right now it mainly comes down to appealing to more customers. Producing neoprene in a range of colours is expensive and if a certain colour doesn’t sell, it’s an expensive mistake for the manufacturer.
Black matches all colours so, it’s safe and it doesn’t show as much when it’s dirty.

If there’s enough demand for brightly coloured wetsuits then the manufacturers will make them. And there are a few colourful wetsuits being made today, it’s just that black outsells them in most cases.

Mike Dodds
Mike Dodds
1 year ago

What percentage of dive accidents do you estimate can be attributed to human error?

Yggdrasil42
Yggdrasil42
Reply to  Mike Dodds
1 year ago

How do you define human error? It’s usually not possible (though lawyers think otherwise) or even desirable to blame one person for an accident. There are many factors at play that each have a role in causing an accident. Intervention at any of those points could’ve prevented it from occurring.
I’d highly recommend reading the book Under Pressure by Gareth Lock, which explains how all those factors cause accidents and what we can do as divers to prevent them. Gareth also has a great webinar course if you’re not a fan of reading.

Alistair Allen
Alistair Allen
1 year ago

Mark clearly wasn’t listening when they explained brownian motion in physics at school.

If you’re worried about contaminats in your gas then change filling stations.
If you think the air goes stale then you really don’t understand science.

Carbon monoxide forming from nitrox in an oxygen clean cylinder… I’d love Mark to explain the science of that!

Kenneth J McArthur
Kenneth J McArthur
1 year ago

Very informative, Mark.

Steve
Steve
1 year ago

Mark, what happened to Simply Scuba?

Matthew Allard
Matthew Allard
Reply to  Steve
1 year ago

he old the business a while ago, from memory he agreed to continue posting on SS youtube page for X amount of months while he transitioned to SDM

Luis J
Luis J
1 year ago

Alec Peirce has a video about this. The speed of corrosion as a function of pressure is an absolut truth, so I’m with Mark on the 35bar part, but you should check Alec’s video about up right vs on their side. Surface area also is at play here

Modern Diver
Modern Diver
1 year ago

As a Transport Canada certified hydrostatic technician my training actually taught it’s best to store your cylinders full. Cylinders stored at less than working pressure can be a potential hazard in a fire due to the fact that as the tank heats up, an almost empty cylinder will not hit burst disc pressure before the metal weakens and catastrophically fails. If a cylinder is stored at working pressure and there is a fire as the tank heats up it will hit burst disc pressure and discharge before the metal weakens. In the dive industry a yearly visual inspection should catch corrosion building up inside and you as the user should also make sure you never drain a cylinder empty while underwater without getting it inspected afterwards.

Thiione
Thiione
Reply to  Modern Diver
1 year ago

Very informative. Thank you!

magraggae
magraggae
Reply to  Modern Diver
1 year ago

That is not with hydrostatic technicians will tell you, at least in the Netherlands. Long term storage it is better for the tank to be stored at 35 bars or 500ish psi. Then again the reasoning for burst disks in case of fire is not a consideration, because they are not used over here.

Jairman
Jairman
1 year ago

#askmark Whats your favorite color?

Scuba Diver Magazine
Scuba Diver Magazine
Reply to  Jairman
1 year ago

Blue

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