How soon do you refill your air tanks?

[hmarashi]

I store them @ 3k. I just have to remember to cycle through them. 4 tanks not to bad. The guys that have a dozen, that could be a chore.

 

[String]

Ive never seen or heard a "only a bit full for storage" recommendation from any tank supplier.

My tanks are always filled ASAP and stored like that ready for use. As im abroad a lot some of my tanks are at 230 bar pressure for 2-3 years at a time with no ill effects. My EAN50 stage i think is over 4 years now full and unused.

 

[hanglide]

From a mechanical perspective, on a hunch I would expect multiple fills to stress the tank far, far more than a constant pressure that is within the tanks ratings. (assuming that the temperature is fairly stable)

Disclaimer #1 - I'm an electronics guy though.. don't take my word on it.
Disclaimer #2 - No idea how "good" the air is after any extended period of time.

Overall - My thought is - dive more, worry less

 

[RonFrank]

I did not come up with the recommendation, read for yourself. I would start with the post I referenced.

Scuba Cylinder Long-Term Storage: Fact and Fiction

 

[hanglide]

Hey Ron-

FWI - Used to live in the Geodesic dome at the top of Double Header Ranch Rd. (first kid was born there in '86 - 10,000ft, December, snow, not always easy to get off the mountain... what a night)

Ahhhh the Memories

Cheers

Scott

 

[Reef_Haven]

For those that do not want to read a book to get a brief answer here it is.

For long term storage (more than 3 months) it is best to store the cylinders at partial pressure.

Steel tanks are much more subject to corrosion than alum.

Tanks used in Salt are more subject to corrosion vs fresh water.

If you suspect your tank has moisture in it remove the valve stem and clean and remove any moisture inside, then fill it.

Storing a tank at 3000psi is better than storing it empty.

Store a tank upright if possible.

Most alum tanks are very corrosion resistant. Steel however can rust quickly, so take precaution if needing to store over a long period.

Thank you Ron for efficiently summarizing the information contained in the linked thread.
Only other thing I would add is.

• Always store cylinders upright

All of the discussion did indeed reference for long term storage - defined as 3 months.

For those that have never heard of storing tanks with low pressure, Here is a quote from the author of the thread. Not to say he can't be disputed.


"An understanding of elastic and permanent expansion has helped me to understand that my scuba cylinders should be stored empty to minimize permanent expansion. Storing a tank at full service pressure increases permanent expansion. However, practical considerations require that cylinders be stored with some pressure (e.g., 300 psig) to prevent moisture from entering."