Tanks in HOT cars and wrecks

[Fishdip]

Well, I was going the 55 MPH speed limit in a Miata MX5 with an aluminum 80 in the trunk, two years ago this September. And it was around 100 degrees and the tank had been in there while I was in the gym. Then a cell phone texting person decided to blow through a double stop sign and hit me because whatever she was doing was more important than both of our lives and property. Dislocated my shoulder and cut my face and hand. Tweaked my neck a bit too. The car, totaled, me, not so good, required surgery. But the tank, good to go.

Did you dive the tank?

 

[happy-diver]

Manifolded tanks bolted permanently 290bar for tyre pumping and in the sun all day before the canopy

and there is a D of emergency O2, 160 bar in the cab, unless there is an aluminium 80 of O2, at 240 bar

that's 40 years of air and 30 of oxygen only managed to lose one 80 of air due to a ccorroded burst disc

 

[NW Dive Dawg]

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?

Didn't read all the responses to this ......but a tank with 200psi is no more dangerous than a bowling ball in your trunk. But if you or your wife are concerned at all then why not just take the 30 seconds to fully bleed the tank, remove the valve then refill at your destination.. With only 200psi you'll need a fill anyway.

 

[Belzelbub]

As long as it has an appropriate burst disk, full may be better.

My LDS has a burst tank near the door. Story is that the tank was in a fire. Tank was not full at the time. As the tank heated up, the metal weakened until it came apart near the shoulder. Had it have been full, the burst disk would have been the weak point. Since it wasn’t full, the pressure never reached burst disk pressure, but the heat weakened the metal such that the metal became the first to break. This was an aluminum tank.

 

[KenE]

I agree this is an emotional argument and using logic will only fail, in my humble experience. Discuss options like strapping them down, valve away from you and 2x6 between you and tanks may help eleviate her concerns. Make her comfortable, regardless of what it takes, your drive will be much more enjoyable. I have found that if they clank, the anxiety increases, ensure they don't make any noise or move. I find this helps her forget about them. Good luck, I know what you are going through!

 

[BackAfter30]

I appreciate all of the answers. Idalia caused us to hit the road a few days sooner so I didn't get to work out additional plans. Strapped down, with 174psi, packed into a corner by the luggage, with the valve toward the center of the car became the final answer.

 

[TMHeimer]

Secure tanks solidly when driving......what else?

 

[BackAfter30]

Well, now part duex...

Somehow, we made it home without my 174psi tank spontaneously bursting and killing us all, and everyone around us. Now I can't fill it. Even just sitting in the basement at 174 it's unsafe in the house. I could use some white papers on safe tank handling and storage. Anybody know of any?

To those who commented on not transporting tanks with her in the car just so she'd not feel stressed, do you continue with the same advice? Do I not own any tanks at all to make Happy Wife, Happy Life?

 

[Belzelbub]

Well, now part duex...

Somehow, we made it home without my 174psi tank spontaneously bursting and killing us all, and everyone around us. Now I can't fill it. Even just sitting in the basement at 174 it's unsafe in the house. I could use some white papers on safe tank handling and storage. Anybody know of any?

What does she think is going to happen? It will spontaneously explode sittin in your basement? In NH? I’ve got several sitting full in my garage in Florida. It’s been ridiculously hot this year, and my garage is not under air. The oldest of those tanks is from the mid to late 90s.

There have not been very many tanks that just exploded. Ever. There were a few old (1988 and earlier) AL tanks that burst. I think in all those cases, the tank was in the process of being filled. I think there’s been a case in the past year with a spontaneous explosion, but that was due to an incorrect valve being installed. Threads on the valve didn’t match those on the tank.

A couple suggestions. Read up on Hydrostatic testing. Every five years your tank needs to undergo this test. It is subject to significantly more pressure during this test than it will ever be filled with.

And watch this Mythbusters clip. Despite trying to make the tank explode, they were unsuccessful. Yes, the tank did propel itself inside the container, but it didn’t obliterate the shark or destroy the container.

Also, read up on the burst disks in tank valves. They are designed to be the weak spot in most instances. Before the tank sees a pressure that would result in a catastrophic explosion, the burst disk will give to release pressure in a safe manner.

But, this is all logical arguments. Which may or may not make a difference in your case.

 

[BackAfter30]

What does she think is going to happen? It will spontaneously explode sittin in your basement? In NH? I’ve got several sitting full in my garage in Florida. It’s been ridiculously hot this year, and my garage is not under air. The oldest of those tanks is from the mid to late 90s.

There have not been very many tanks that just exploded. Ever. There were a few old (1988 and earlier) AL tanks that burst. I think in all those cases, the tank was in the process of being filled. I think there’s been a case in the past year with a spontaneous explosion, but that was due to an incorrect valve being installed. Threads on the valve didn’t match those on the tank.

A couple suggestions. Read up on Hydrostatic testing. Every five years your tank needs to undergo this test. It is subject to significantly more pressure during this test than it will ever be filled with.

And watch this Mythbusters clip. Despite trying to make the tank explode, they were unsuccessful. Yes, the tank did propel itself inside the container, but it didn’t obliterate the shark or destroy the container.

Also, read up on the burst disks in tank valves. They are designed to be the weak spot in most instances. Before the tank sees a pressure that would result in a catastrophic explosion, the burst disk will give to release pressure in a safe manner.

But, this is all logical arguments. Which may or may not make a difference in your case.

I’m pretty sure I understand hydro and burst disks, but it can’t hurt to make sure my understanding is complete.

The Mythbusters clip is good. She had found the one above but couldn’t make it through the whole thing. Missed the .50 test. Impressive. She would get through the MB clip.