Scuba Tanks vs. Heat???

[eelnoraa]

Many already mentioned, it should be fine. What human experience as a large temperature change, say 50F to 100F, is actually a relatively small change if you use absolute temperature scale. 50F=10C=283K, 100F=37C=310K, 10% change in Kelvin.

So you fill your tank in a fairly cold night(50F) to 3000psi, and use it on a blazing hot summer day(100F), you tank pressure will only go up by 10%, in this case 3300psi, very manageable.

 

[GrumpyOldGuy]

Many already mentioned, it should be fine. What human experience as a large temperature change, say 50F to 100F, is actually a relatively small change if you use absolute temperature scale. 50F=10C=283K, 100F=37C=310K, 10% change in Kelvin.

So you fill your tank in a fairly cold night(50F) to 3000psi, and use it on a blazing hot summer day(100F), you tank pressure will only go up by 10%, in this case 3300psi, very manageable.

You might want to consider on a blazing hot summer day, that 100F ambient is measured in the shade. You put a black tank out in the sun for a few hours and it will be much hotter than ambient, too hot to touch. Although the tank will probably still not blow the burst disc, it will stress the tank just like an over-fill and shorten its life.

 

[Marek K]

(i.e, the cylinder can explode).

i would love to see this...:d

:d:d:d

 

[Crush]

I would love to see this...

You will need shape charges to see it.

 

[SC_Hoaty]

You will need shape charges to see it.

A place I used to work did some destructive testing. All high pressure d-tests were hydros (less stored energy with incompressible liquids). We had a show-and-tell case in the lobby of two identical cylinders (small, about 1"D x 5"L) - one was a pneumatic overpressure, the other a hydraulic one. The hydro had a bulge an nice straight split. The pneumatic one looked like a flower, with the metal peeled back (where it was not completely missing!). Dramatic evidence.

 

[Crush]

A place I used to work did some destructive testing. All high pressure d-tests were hydros (less stored energy with incompressible liquids). We had a show-and-tell case in the lobby of two identical cylinders (small, about 1"D x 5"L) - one was a pneumatic overpressure, the other a hydraulic one. The hydro had a bulge an nice straight split. The pneumatic one looked like a flower, with the metal peeled back (where it was not completely missing!). Dramatic evidence.

I should have been more specific - any burst disk will blow way before the tank does.

Why would the pneumatic and hydraulic overpressures behave differently? The overpressure must have been extremely rapid (and therefore non-representative of tank warming) for this top happen.

 

[SC_Hoaty]

I should have been more specific - any burst disk will blow way before the tank does.

Why would the pneumatic and hydraulic overpressures behave differently? The overpressure must have been extremely rapid (and therefore non-representative of tank warming) for this top happen.

You are correct - the burst disk is an overpressure device that is intended to fail before the cylinder itself.

Regarding the difference in hydro vs pneumatic testing - compressed gases will expand (stored energy). Compressed liquids (especially ones selected for this use) are virtually incompressible, and do not change volume when their containment (the cylinder) fails. Compressed Gas - lots of stored energy. Compressed Liquid - not so much. This is not related to the rate of increase. However, there was NO pressure relief on the cylinders - the intent is to test the cylinders themselves.

When you carry your tank in for its 5 year hydro, you know why it is not a 5 year pneumatic test. If it failed, someone might die.

Good question - hope I have answered it. If not, rephrase and I will try again

 

[Crush]

Compressed Gas - lots of stored energy. Compressed Liquid - not so much.

The "flowering" of the tank indicates multiple failure points, which is usually indicative of rapid pressure changes. The split line is indicative of a single failure point. The initial failure is caused by pressure, not potential energy.

I suppose, put another way, it is easy to gradually increase the tank pressure with a gas - this is likely what happened. It is similarly difficult to gradually increase the tank pressure with a liquid, at least with most hydraulic setups.

 

[D_B]

as the tank/temperature has been answered already, I think I see what SC is saying .. with the incompressable fluid, when the tank fails, the pressure goes to 0 rapidly , With the compressed gas, when the tank fails, the gas pressure does not drop as fast and continues to expand through the opening and has more time to work on it making it bigger

?

 

[captain]

You put a black tank out in the sun for a few hours and it will be much hotter than ambient, too hot to touch. Although the tank will probably still not blow the burst disc, it will stress the tank just like an over-fill and shorten its life.

Maybe on planet Mercury, not on planet Earth