Chris vs. House

19 Dec

Hi Everyone, Chris here.  Its been a while since I have posted. For the last two months I have been working very hard on a new show for Discovery called “Never do this at Home“.  Last week was the big finale and lucky me I am off for a couple weeks !  The finale was sort of “pre” released through a local new channel. Which is great because then I can talk about it ! Usually there is a clause in our contracts that we cannot give away the content of the show before it airs. However if its released through another channel then I can talk about it. Its a funny system but I guess it saves the show from losing all its secrets. You can see the news clip at the link below:

http://kitchener.ctvnews.ca/video?clipId=823963&playlistId=1.1074170&binId=1.815923

Oakloand House Explosion News

We used propane to demolish the house. This is apparent due to the very slow nature of the explosion. I know “slow explosion” sounds like an oxymoron, but in our field there are many types of explosions. We classify explosives as high order, or low order depending on their ability to produce work and the speed in which they do.  A propane explosion is a very slow almost ultra low order explosion as it travels at about one foot or so per second. Compare this to detonating cord, one of the fastest common blasting agents which burns at 4 miles per second.  At the bottom of this post I have attached two videos, one of the Never Ever propane explosion/ new real, and one of an explosion of approximately 150meters of det cord. In real time the difference is unbelievable.

On Never Ever, the hosts had wanted to simulate a gas leak explosion (which by the way, if you want a first hand account of one, ask Jess, she survived one). Gas leaks are tricky things mostly due to the properties of propane, which is heavier than air and is most explosive around a 4% mixture. Get this mix too high and the result is a flash fire, too low and there is either no ignition or no percussion or crack to the explosion. The crack is the change in ambient pressure which actually doing the work. The pressure change is caused by the creation of gas through a chemical reaction in the explosion. Again differnt agents produce differnt amounts of gas. Amex, a mining agent for example, creates 1000 liters of gas for every kilo present. There is no wonder that it can blow the side off a quarry or vaporize a truck, like we did on D-Day to Victory.  A 100 kg bag going off is instantly creating 100,000 liters of gas so fast it actually compresses the ambient air. I will post another video later to show this , its like the matrix in real life !

Back to exploding houses, so far we know that propane is slow, heavy and only really explodes with great force at 4% mixtures. These properties presented some problems in our house scenario, we needed first to circulate the air in the house, otherwise the propane would settle out on the floor. Also we needed to make sure there was an even distribution of propane throughout the house. If not, only pockets would explode and flash fires would result in other areas. To work around this we installed ducting and special “explosion proof” fans to circulate the air. These fans are guaranteed to not spark, however they do not seem all that “explosion proof” once you drop a house on them.  The only other problem and it was a doozy was that the house leaked! It was a drafty old farm house and we did not want our propane to sink into the walls, floors or basement. The fix was about 2500$ worth of plastic vapour barrier and tuck tape. Effectively we sealed the house to the point it was one big plastic bag. Flash bags were wired and leads were run to our bunker. Next we filled with the house with the appropriate amount of propane, 60lbs or so for a 13,000 cubic foot house. Then. . . KABOOM.  It was a nice orange fireball, showing us we were a speck on the rich side. The house still blew up great and the visual was amazing as well.

All in a days work!

And here is a high order PETN explosion for comparison. This video was shot in super-slow-motion. I will upload a real-time version as well.

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