Valve front or back?

[paulwlee]

I usually try to put the tank in my car trunk (Mustang.. barely fits) sideways. I used to load my tanks valve backwards, but after thinking about what would happen if I were rearended, I stopped doing that.

Now about the front/back question. This is my take. When the valve flys off, it's propelled by about 3000psi*1inch^2= 3000lbs for a fraction of a second. Maybe .01seconds? The tank, on the other hand, is propelled by about the same force(steadily diminishing as air drains) until the tank drains out, which would probably be a few seconds. Which means, that the valve, if it hits something, like the back of your seat, will lose most of its energy and will probably bounce back. The tank however, is continuously being propelled, and even after hitting something, will tend to continue to exert force by itself. So, it seems to me, that the tank is much more dangerous. (And the initial energy will be larger too with the tank.)

This is what I infer from freshman physics anyway..

 

[MXGratefulDiver]

It's like comparing a high-powered bullet to a rocket-propelled grenade. Either one can kill you.

At 3000 psi the valve will lose a bit of velocity, but back of your seat won't stop it ... neither would your spine. It'd probably bounce back when it hits your engine block though ... :wacko:

... Bob (Grateful Diver)

 

[DA Aquamaster]

In a sense you can attempt to minimize the damage in a worst case scenario (ie, you get rear ended with enough force to break the valve off a tank). But in doing so you are potentially increasing the risk of dropping a tank while loading or unloading it. (ie, you drop the tank while manuevering it around to fit in the trunk or back of your SUV and drop it breaking off the valve and launching the tank.)

Personally, I load 'em valve backward as I am not required to shift or change my grip to accomplish it. The tank is securely under my control through the whole operation. The valve is also right there handy when I go to get the tank out of my Explorer or Cherokee. In a major rear end accident, there is probbaly more risk to me, but the day to day risk of dropping a tank and breaking a valve is greatly reduced, so overall I am probably safer.

As an aside, the valve is smaller, lighter and almost by definition in direct contact with whatever object just broke it off, so it is very unlikely to cover much distance or acquire much kinetic energy (mass times velocity squared), so it really would not be much of a threat. The tank on the other hand, has it's own on board propellant that will develop a lot of thrust and the tank will acquire a great deal of momentum (mass times velocity) and continue to fly at a fair rate of speed long after the air runs out.

Tanks also lack stabilizing fins and do not fly straight. My one and (hopefully) only experience with tanks going ballistic was as a kid on the family farm when a large partially full O2 tank fell over broke it's valve. It shot out the open shop door but was not what you would call a smooth flight as it twisted and spun rather erratically before bouncing to a stop a couple hundred yards away. Neither dad nor I thought it would be wise to tell mom what happened.

 

[DiveTub]

Scuba Tank Explodes in the boot of the car

 

[redacted]

I can only imagine what it must have done to the driver's seat.

 

[metaldector]

I saw these same photos it was in Spanish on a South American web site. I can't see a license plate in the photo to resolve the question but that isn't an Austrialian car as they have right hand steering and that is a left hand vehicle. But the main point is, BOOM!:wacko:

 

[Scubaroo]

A former buddy from SF had an aluminum tank laying sideways on the back seat of a Landrover (this was in Western Australia during his travels) - hot day, tank in the sun, the valve blew off the tank, punched a hole through the door of the Landy and was never seen again - presumably landing somewhere in a paddock on the side of the road! Tank stayed in the back seat, slammed against the other door.

Guess it all depends on the particular tank.