TARGET 090729 Railroad Tank Car Vacuum Implosion

Remember back in high school science class when the teacher sucked all the air out of a strong metal can, and it crumpled like a paper cup? Well, there are times when that is more than just a science class demonstration. A vacume can be a powerful thing out in the real world, too. Incidents of the type you see above are real. The hose on the bottom of the tanker was most likely a steam line. All you need is a cool day, a cold rain, an un-insulated tank or rail car and a steam source. This type of implosion can happen even if you don't intend it. If a tanker is sealed and being cleaned with steam and a cold rain suddenly causes a vacume to form inside, that high school science project becomes a full-sized reality. The general-purpose tank car in the photo below was being steam cleaned in preparation for maintenance. The job was still in progress at the end of the shift so the employee cleaning the car decided to block in the steam. The car had no vacuum relief so as it cooled, the steam condensed and the car imploded.

Keep in mind that steam has around 1600 times the volume of condensed water. That means that when the steam condenses back into water, the resulting volume is 1/1600th of what it was. If there is nothing to fill in that space, then a strong vacume occurs. The same thing can happen with chemical vapors. There are also when a sealed tanker contains chemical vapors, and a sudden cooling causes the vapors to condense on the inside. The material in the air condenses in size leaving much lower air pressure and - whoomp! You might ask then, why not always leave an air line open to the outside so these vacumes won't happen. The reason is simple. When the sun comes out or there is some other heating of the tanker's contents, the vapors of some cargo are poisonous or corrosive, and therefore, a line to the outside is not allowed. Most of these tankers have a failsafe vacume pervention valve, butlike all mechanical things, they can fail, with the result shown below.

So why don't we hear more about this kind of thing happening? Because such accidents are usually not dangerous, since they generally only happen to empty tankers. When a tanker is full, the volume of vacumized space is generally not enough to collapse the tanker. This target was designed with the hopes that you would pick up on the suddenness of an event. We also hope that if you heard the sudden sound, you were curious enough to describe it. The sound will be a very low-pitched "whump" sound accompanied by the creaking of bending metal. There will generally be accompanying smells of industrial chemicals. If you got these, then consider that you did a great job of viewing. Give yourself a good pat on the back....that is, if you wrote the impressions down. If you gained information in your session which was not covered in the feedback, please take a look at the following link: YouTube Video. If the link gets removed perform this search in Youtube. Train Car Implosion Many thanks to Ray McClure for suggesting and programming this target.