Scuba Tanks vs. Heat???

[PotatoC]

Really don't want to look like an idiot on here but oh well.. Lived in northern MI my whole life, never had to deal with real high of temperatures. Just moved to North Carolina where today was 90 and I am told that the humidity is going to kick in soon and make it real warm..

So, I have five scuba tanks.. No basement.... Can I keep them in my North Carolina non air conditioned, humidity filled garage???? Can I store them there all year?????? Sorry for my ignorance, I have never lived in the south, nor been in this heat and just want to play it safe. Just not sure where to put them. Thank you for any positive advice!!!!! TJ

 

[iztok]

Physics don't change between Michigan and North Carolina

Recently we did some math on this but it boils down that you can keep them even in the car and temperature increase should not create pressure that is even close for a burst disc to burst.

Magic is PV = nRT

 

[iztok]

BTW: Humidity doesn't matter for the tanks. It only affects human perception

Granted issue might be rust but that is another story. Keep tanks dry from outside and don't let them empty where dampness can come inside and you are set.

 

[seaducer]

Watch out for rust, corrosion and mold. Otherwise they will be fine.

 

[Doc Harry]

There should not be any issues with storing your cylinders at those temperatures, provided that your cylinders have a valid hydro stamp, a valid inspection sticker (that is, that your cylinders are properly maintained), and your valve has a burst disk. (All valves made for use in the USA have a burst disk.)

If there are any issue with overpressurization, the burst disk should burst to relieve the pressure.

The burst disk is designed to prevent the cylinder from exploding. However, if your cylinders are severely corroded from lack of proper use and maintenace, then the cylinder wall can fail before the burst disk fails (i.e, the cylinder can explode).

 

[herman]

Hate to tell you this Tater but 90 is a nice warm day, just wait until the 100+ in August. Seriously, 100- 120 deg is nothing to a tank. Once in a rare while a tank will blow a burst disk when in a hot car but odds are it was weak to start with. There is no need for concern..

What part of NC, there are a lot of active divers in the Raleigh and Charlotte areas.

 

[Crush]

The thread on scuba tanks in a hot car trunk is here: http://www.scubaboard.com/forums/basic-scuba-discussions/335436-scuba-tanks-my-car-trunk.html

iztok is right - humidity outside the tank doesn't matter.

My response at http://www.scubaboard.com/forums/5244637-post14.html is repeated here:

FWIW, within the ideal gas approximation, the increase in pressure (or volume) upon heating is:

Tf/Ti

where Tf is the final temperature and Ti is the initial temperature. All temperatures are in terms of Kelvin - for a Celsius version:

(TCf+273)/(TCi+273)

where TCf is the final temperature and TCi is the initial temperature, both in Celsius. I believe that the conversion from Celsius (TC) to Fahrenheit (TF) is:

(TF-32)*5/9 = TC (could be wrong).

If a tank is filled to 3000 psi at 25C (TCi=25) (77F?) and will burst at 5000 psi (I am just making this up), then

(TCf+273)/(TCi+273) = 5000/3000

TCf = 5/3 * (TCi+273) - 273
= 5/3 * (25+273) -273
= 224 C or 435 F

So, your tank will have to heat to 224C/435F for the tank to rupture at 5000 psi.

Caveat - real gases depart from ideal gas behaviour at high temperatures and pressures such that 224C/435F should be thought of as an extreme upper end temperature - the true pressure at 224C/435F will be higher than the ideal gas case of 5000psi. This corresponds to the bursting pressure being lower than the 5000psi ideal gas case. Just a guess, but I would allow up to a 20% departure from ideal gas behaviour (this is a bit extreme) at 5000psi leading to

TCf = (5-5*.2)/3 * (TCi+273) - 273
= 4/3 * (25+273) -273
= 124 C or 256 F

Now the tank bursts at 124C/256F rather than 224C/435F. 20% here and there goes a long way...

The true departure from ideal gas behaviour of dry air is quantified, but I don't have the number in front of me right now.

 

[Stu S.]

Tanks are just fine in the NC garage. Just don't put your gear in a North Carolina Attic. My dive gear went up to the attic in Wilson, NC. The heat molded all the rubber items into the shape of the dive bag. Those were my favorite fins, too.

 

[Hammerhead]

There should not be any issues with storing your cylinders at those temperatures, provided that your cylinders have a valid hydro stamp, a valid inspection sticker (that is, that your cylinders are properly maintained), and your valve has a burst disk. (All valves made for use in the USA have a burst disk.)

If there are any issue with overpressurization, the burst disk should burst to relieve the pressure.

The burst disk is designed to prevent the cylinder from exploding. However, if your cylinders are severely corroded from lack of proper use and maintenace, then the cylinder wall can fail before the burst disk fails (i.e, the cylinder can explode).

I would love to see this...

 

[TMHeimer]

I never leave them in a car-may put the 2nd tank under the car out of sight if cracking windows is not an option. Tanks are made to withstand 180F or 82C. The burst disk blows if tank pressure exceeds 140%. If they are not in a car (or other enclosed area) and you don't reach these limits, they should be OK. You may have something to worry about if you lived in, say, Ecuador at the Equator, and you left them in the sun.