Temporary Storage of tanks in the cold

[grouchyturtle]

I've seen this posted before, but this question relates to a detail, which wasn't brought up in any of the other posts.

Most people recommend storing tanks indoors for the winter. I think the reason they gave was that extreme temp changes, especially cold, can cause moisture to build, but...

What about storing them in a cold garage just for a few months, while still being used? It's already getting pretty cold here in NJ, at least in the morning and at night, but it will be the same temp at the dive site, and the season ain't over yet!

[DA Aquamaster]

I own numerous steel tanks and store them in an unheated shed. I have never had a problem with extremes in temps causing condensation (and it can get to 30 below here).

The air used in scuba tanks is very dry and condensation is just not a problem with dry air. If the air in your tanks is moist enough for condensation to be an issue, you are going to have problems anyway even if the tanks are stored indoors.

I also normally store them with the 500 or so psi remaining from the last dive except for a few that are kept full for the occasional ice dive over the winter. I suppose that less air in the tank would also mean less mosisture and less potential for condensation as well.

[compressor]

I agreee w/DA Aquamaster. Have had tanks for 25 years and usually stored in cold garage during the winter. Always leave air in the tanks, assuming the air was of good quality you should never have a problem.

[pescador775]

The air inside the average scuba tank is not moisture free. However, tanks are dryer than they used to be thanks to filtration; dessicant chemicals like Vaporshell and a few simple changes to compressor design including the backpressure valve and micronic filter have made a difference. Generally, these systems will reduce the relative humidity inside the condenser to something less than 100% at 2000 psi, a typical valve setting. They accomplish this trick by agitating or accelerating the air, decelerating it and exposing the moisture laden gas to huge surface areas posed by the micronic filter. The air is then pushed through a dessicant chemical which has a very high moisture absorption coefficient. The resulting air has a dewpoint of about -40F at atmospheric pressure. Inside the tank, at high pressure, this dewpoint will be higher but not enough to cause condensation at room temp. The actual amount of water in a full tank is about two drops. This is in gaseous form of course. A hyperfilter will drop the dewpoint to -60F and one drop of water, dry indeed when one considers the huge amount of air in a pressurized tank. A tank with reduced pressure should produce no neat water or frost at low ambient temps. A full tank might see a tiny amount of frost at extremely low temps. It would take many years to produce enough rust to cause concern.