Tanks in HOT cars and wrecks

[BackAfter30]

I know there have been discussions related to this. I'm hoping for a fresh direct answer to someone - my wife - concerned about cylinder safety in vehicles.

She spent many years in manufacturing and in the coarse of that work experienced the damage done by 200psi vessels/lines breached unexpectedly. With that background she is concerned about transporting a tank I picked up in FL back home to NH. We're experiencing mid 90's temps and expect that most of the way home on a leisurely four day return trip.

I'm not talking about my drive from the house to the dock or the beach, I'm talking about our long trip home from FLA.
She is worried about both overheating, and decapitation. I've already run the tank down to less than 200psi. She still thinks that it can overheat and "explosively fail", or that it will become a certain lethal missile after decapitation in a collision.

My math says that starting at base conditions of 90degF and 200psi, a hot car temp of 150degF (not gonna happen) would yield a pressure of ~250psi. I don't have a concern about that pressure; am I wrong to not be concerned?

My feeling is that a AL80 at 200-250psi getting decapitated is not a concern (yes, that's 200psi through about a 1sqin opening acting on a 30lb object would accelerate it, but it would exhaust that pressurized air before the tank really got up a head of steam); am I wrong to not be concerned about that?

 

[L13]

@BackAfter30, Lets work it out:

• P=nRT/V (from high school chemistry)
• n,R, and V are constant. T is in absolute units (R instead of F)
• P2 = P1*T2/T1 or T2 = T1*P2/P1
• for imperial units P1 = 200psi, T1 of 75 F = 535 R
• T2 if P2 = 400psi (much less than the 3000psi working pressure)
• T2 = 535*400/200 = 1070 R = 610 F ==> you don't have to worry about it!

 

[iointerrupt]

Run it down to 0psi and forget the whole thing. While it makes sense to keep some pressure in a tank for long-term storage, "just in case", it isn't worth devoting any mental energy to if there's reasons otherwise.

People that fly with a pony bottle, carry them with no valve at all, land in hot, humid tropical environments, slap the valve on, fill them up and dive without a second thought.

(And yes, if you trust strapping a cylinder with 3000psi to your back, surely you'd trust it at 250psi too.)

 

[johndiver999]

you should be worried about being decapitated by a flying tank inside the passenger space of a motor vehicle. The air in the scuba tank is nothing to be worried about, think about all the energy in the gasoline fuel tank you are sitting on. If it worries her, drain the scuba tank to 50 psi, it won't matter.

 

[lexvil]

The smart thing to do is rent tanks there, not because of any tank related danger but because you’re married.

 

[BackAfter30]

The smart thing to do is rent tanks there, not because of any tank related danger but because you’re married.

Things have already happened. This is what I have to manage.

 

[MB NZ]

Had an extremely clever mate (PhD physics) who put a steel cylinder on a smouldering BBQ to make the point that it was perfectly safe. It made for a somewhat fraught dive club meeting.

 

[rx7diver]

I know there have been discussions related to this. I'm hoping for a fresh direct answer to someone - my wife - concerned about cylinder safety in vehicles.

She spent many years in manufacturing and in the coarse of that work experienced the damage done by 200psi vessels/lines breached unexpectedly. With that background she is concerned about transporting a tank I picked up in FL back home to NH. We're experiencing mid 90's temps and expect that most of the way home on a leisurely four day return trip.

In the USA, burst discs are required. Strap down the cylinder. I wouldn't worry beyond that.

ETA: Oh, and don't place the cylinder in direct sunlight.

rx7diver

 

[NaCl H2O]

I live in south FL and have kept tanks in my truck for several days over many, many years.
Like last week with very high 90's, and what, another 15-20 degrees higher inside my vehicle?
Not a problem.

Per above, hitting the brakes on I95 making 30+ pound steel tanks break free and roll around did some damage to the interior of my truck. Tanks were fine though.

Edit* full or ~500 psi, no problem unless they are loose!

 

[Marie13]

I have a couple of steel tanks that permanently live in my car. I’m in the Midwest. They’ve not exploded or anything, even with the 100 degree heat we had two days this week. I won’t leave my rebreather O2 tanks in the car all the time like that, but the ones with air? I don’t worry about it.