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Author Topic: Why train derailment causes fire?  (Read 2516 times)

Offline jjoll

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Why train derailment causes fire?
« on: 27/03/2015 16:49:45 »
What causes train car that is full of crude oil to catch fire (after derailment)? Does the collision create enough heat for the crude oil to catch fire? I have watched Mythbuster and I can remember once in their show they were trying to shoot at gas tanks to make them explode but they couldn't since the bullets were not creating enough energy or the gas to ignite.


 

Offline David Cooper

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Re: Why train derailment causes fire?
« Reply #1 on: 27/03/2015 21:47:37 »
Most likely sparks - I've seen sparks come up from a cyclist crashing ahead of me during a race.
 

Offline chiralSPO

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Re: Why train derailment causes fire?
« Reply #2 on: 28/03/2015 02:27:21 »
A train has WAAAAYYYY more energy than a bullet.

A freight train with a mass of 10000000 kg (10000 tons) traveling at 10 m/s (22 mph) has 500 MJ of kinetic energy. Even a high powered round is unlikely to be fired with more than a few kJ of kinetic energy.

Releasing 500 MJ of kinetic energy in less than 10 seconds is likely to cause some very high temperatures!
 

Offline evan_au

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Re: Why train derailment causes fire?
« Reply #3 on: 28/03/2015 07:43:37 »
The metal involved in the collision also makes a difference:
  • Steel rails and steel tanks are very hard, and will produce lots of sparks until the train comes to a halt (and even then, the metal will remain hot).
  • Lead in the bullets will deform on impact, absorbing some of the kinetic energy, and reducing the chance of a puncture. Lead is too soft to produce sparks in the same way as steel.
  • A steel-jacketed bullet may produce a different result; it may produce some sparks as it exits the tank, but there will be no gas on the outside of the tank when it exits. 
 

Offline yor_on

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Re: Why train derailment causes fire?
« Reply #4 on: 28/03/2015 23:51:26 »
You need something over 800 degrees Celsius, I think? Long time ago I had a friend that made a bet that he could threw a bucket of oil into a open fire place and put out the fire before that oil alighted. He won that bet. So you need to get that oil heated up properly, but once it starts to burn I've also heard that it is much harder to put out. Then again, maybe there were other materials involved?
 

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Re: Why train derailment causes fire?
« Reply #4 on: 28/03/2015 23:51:26 »

 

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