Tanks in HOT cars and wrecks

[inquis]

My math says a mere 222 psi, but bringing logic to an emotional argument may not be the best play. She's worried. Taking the valve off completely will address that. Tape the opening to avoid contamination. Transfill 200 psi back in when you get home so your fill shop will be happy.

TBH, you might want a vis anyway if you just got this used.

 

[Boarderguy]

My steel 100 cold filled to 3650 psi was reading 3850 after spending 10 hours in the back of my truck (with a canopy on) in 93° weather. Your tank won't explode with 200 psi even if thrown in a fire pit and hit with a hammer.

 

[Jaan]

We took a road trip down to the keys with our steel tanks in the hatchback and I was actually quite surprised at how cool it remained in there despite parking in the sun for hours. We also keep our tanks in there all the time (rotate from time to time when not in use) . Not worried about them blowing up.

We do place the valves inside, in case we're rear ended and they somehow 'go flying', the thought being that at least they will fly in the opposite direction of us in the front ...

I saw a story about one going through a concrete wall at one point...

And another fun video .. Don't try this at home.

 

[TMHeimer]

I assume you'd take them into motels when stopped. When stopped to shop or eat maybe crack the windows and park where you can see the car for theft. When diving slip other full tank(s) way under the car. I've done these things on trips.

 

[Rob9876]

Show your wife these videos:

 

[Fishdip]

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?

So two things I have had AL80 "cold filled to 3400" in a truck bed so direct sun when its 119 out and they did just fine for days. Now with that said I will never ever transport any heavy object inside a vehicle with out strapping it down "even a tow ball". When I was about 20 I was the first to find a rolled over SUV on a back road and the person had a 10 pound workout weight in the car. Lets just say it did not stay in the back and driver was DOA.

 

[OTF]

It's silly, but drain the tank and take the valve off if she's worried. Slap some masking tape over the tank neck to keep dirt out.

Not sure if your wife would be more or less concerned, but certainly shocked by the things that Florida cave divers routinely leave baking in the parking lot under the hot summer sun... 2400psi rated cylinders filled to 4000psi, stacks of 3500psi 100% oxygen bottles for rebreathers, scooters with huge homemade battery packs... and their cars aren't exploding very often. It's one of those things that feels dangerous but usually isn't.

Now, the risk of a tank going off in a serious car crash does strike me as a real concern, though very low probability. I try to position the valves in a way that they're less likely to be sheared off by a hard crumpling impact. Usually strapped vertical to a seat, or lying in the back footwell or trunk with valves toward the center of the vehicle.

 

[eelnoraa]

@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!

Absolute temperature unit is "K", right?

 

[L13]

Absolute temperature unit is "K", right?

Kelvin is Metric(same increment as C), Rankine is Imperial(same increment as F).

 

[GDHLEWIS]

Live in the Middle East and not once has anyone here had an issues with leaving tanks in cars / in direct heat. Even on longer days at the beach when the tanks are in direct sunlight its not been an issue.