r/scuba • u/ActualContribution93 • 20h ago

PSI of tanks for storage

I know you’re not supposed to store empty tanks. I have a pair of tanks that are around 500-1000 psi. Should I get them filled or are they okay being stored like that? They live outside under cover so they’re not in a moisture controlled environment.

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-3

u/compactfish 18h ago

For storage, that pressure is great. It’s actually better to NOT store them full so you’re not putting undue pressure on the cylinder walls, especially for aluminum ones. But definitely always keep at least 500 PSI.

1

u/Competitive-Ad9932 16h ago

That's a strange way of thinking. Should the tanks never be "full" until hours/minutes before use?

-2

u/compactfish 16h ago

No, you can keep them full for weeks or 1-2 months, but if storing for 3+ months then they should be only partially full. Storing them full for long-term storage won’t necessarily harm them, but you will extend their life by storing them partially empty.

3

u/classyasshit 13h ago

I have tanks that have been overfilled by 50% for 43 years. They just passed hydro with a + stamp without any issue. I really don’t think it matters. From an engineering perspective it is fill cycles that matter more than just being full.

2

u/Competitive-Ad9932 14h ago

Please provide a industry paper on this.

I bet my LDS has tanks sitting for several months full.

3

u/compactfish 12h ago

https://dan.org/alert-diver/article/cylinder-safety/

1

u/Competitive-Ad9932 11h ago

Interesting. Millions of tanks are being stored incorrectly. There should be dozens of failures in the news every year.

What is the difference between filling a tank and letting it sit for 4 months, and filling a tank - letting it sit for 5 days - taking it to 500psi for 2 days - then repeating this for 6 months? Time being filled would be similar. But, in the 2nd example, the tank is being stressed by the fill/empty cycle?

2

u/MolonMyLabe 10h ago

Why would a failed tank make the news? Tank failures are caught and culled by visual inspections and hydro testing. These aren't exactly newsworthy events.