What causes tank car implosion

What makes this happen?

Hose is connected to a vacuum pump to empty tanker car - The contents of the tanker were unloaded pump kept running pulled a vacuum on the tank car and the atomospheric pressure collapse the car.

This topic is not specific to New Jersey, so off to General Discussion we go!

-otto-

no vacuum system needed, the weight of draining liquid (if not vented) is enough to have a tank car implode.

Actually what this is is the reversed video of the new inflatable tank car. UTLX has a few of these I hear.

"Uh, thats enough, looks like she's empty!"

I bet it makes it much easier to scrap, don't even need a ladder!

Next time, buy American.

Like this one you mean ????

Do tank cars have any kind of emergency vacuum release valve (like the opposite of an over-pressure valve on a steam boiler) to prevent this from happening? (obviously if they do, they failed in the examples above)

I have heard/read (this means find your big grain of salt) that this happens when a multi-use tank car gets steam-cleaned in between loads, and the valves are closed before the temperature stabilizes.

When the steam cools and condenses, the resulting pressure differential (which is almost a vacuum) inside the tank causes the implosion.

- litz

Plate F wrote:Actually what this is is the reversed video of the new inflatable tank car. UTLX has a few of these I hear.

Sucked in tank trailers are repaired by blowing them back out w/ compressed air. They blank off the pressure relief. The current trailer standards do require a vacuum and pressure relief but I don't know if trankcars are the same.

Either scenario is possible. Pumping out an unvented tank it will implode just as the contents empties.

Steam cleaning heats the interior so hot that it must be vented until cool. We used to use one dog near the hinge to wedge the manway open while they cool w/ out getting rain in.

That Sux!!!!

That sort of thing can also happen to large covered hopper cars that drop their one hundred tons of grain in just a minute or so. That's why you have to have the top hatches open before opening the bottom gates. We had that happen on a few of the first jumbo covered hoppers on the C&O/B&O in the late 1960s.

the vacuum pump pressure isn't just enough to make the car implode, it must be the pressure that was built inside that made it give in.

archebald23 wrote:the vacuum pump pressure isn't just enough to make the car implode, it must be the pressure that was built inside that made it give in.

No, it isnt inside pressure that implodes the car, its outside pressure ... Its essentially the weight of the earth's atmosphere (air) crushing the car (air has weight..air is VERY heavy..same concept as water pressure deep under the ocean).

When the car is full of air, or liquid, there is equal pressure on all sides, inside and out, (or there can some *increased* pressure inside the car, if the car is equipped to handle that..but not too much, or the car will explode) but if you take away the "support" of the air inside the car, by creating a vacuum, the weight of the air outside crushes the car.

Think of blowing up a balloon..you add more air to the inside of the balloon, the inside air pressure becomes greater than the outside air pressure, and the balloon expands..you can also explode things by adding to much air pressure to the inside..
this tank car implosion is the opposite of exploding a tank car by adding air pressure ... you *remove* the inside air, (rather than adding it) and the *outside* weight crushes the car inward..

You can do the same thing by sucking the air out of a milk jug or other small container ... the milk jug isnt being crushed by any inside pressure..it is being crushed because you remove the inside air, creating a vaccum, (or a partial vaccum, it doesnt have to be complete removal of all air) then the weight of the outside air crushes it inward.

Scot

edited by a Moderator (format) July 31, 2010, 1033am CDT