Each episode of popular scientific TV program «Mythbusters» is usually devoted to two popular myths. In one of new series of the program we’ll appeal to a legend about cylinder-rocket.
Is portable cylinder with propane able to rocket in the air like a real rocket?
Imagine that the shed with gas cylinders inflames. At the explosion a cylinder turns to a rocket: it breaks through the roof and shoots up for 50 meters. Experts-busters, Tory, Grant and Kari took up this myth to experimentally test it to its limits.
Cylinders with propane as all other cisterns under the pressure are equipped with insert valve wherethrough the excesses are bleed down in case of necessity. This put explosion possibility in doubt. Only if we create a fire of such power that gas will not be able to run into the valve.
Theoretically gas cylinder turns to a rocket in the following way: a cistern hits up, inside pressure grows up and the cistern finally explodes. Gas comes out and burns, consequently the cylinder flies up to the air.
Plan A. Mythbusters created small shed where they installed the main star of the show – 10 liters cylinder with propane. To maintain the experimental integrity the fire was organized from usual firewood and coal. Burnt and started waiting.
Wooden shed turned to huge wood fire. At the temperature of 800 degrees the vales exploded but the cylinder didn’t even move. The valve diminished gas pressure faster than it could accumulate in the cistern. In fact, a real explosion didn’t occur, launching wasn’t succeeded.
So, a myth about the shed was spectacularly failed. Disproved! Conclusion: in usual conditions it’s not possible to get from a cylinder with propane flamy rocket strained to the air.
Plan B. The busters decided to improve the experience – they replaced security valve by a cover. They started warming up closed cylinder by portable burner. Gas started expanding, cylinder – dangerously becoming round… Massive explosion blew the pieces of the cylinder to the four winds of heaven. Explosion wave blew out burners flame.
Plan C. The busters weakened the body of the cylinder by a sink made in the bottom (an effect of old cistern). This time during explosion gas went around and above, cylinder was torn to pieces, but the vertical remained unbowed. And again no any rocket.
Plan D. What if the cistern will be half empty? What’s the dependence from propane power capacity? There was installed a launching platform on the testing range. The cylinder was burned and little bit later there was made a shot to the bottom to create a nozzle… Launching was succeeded – the cistern rocketed into the air, a real rocket.
But it’s reasonable to remember that to do that there was necessary to create simulated conditions!
Which conclusions is it hard to escape after watching this program? We often hear an expression-complain: “gas exploded”. And we start to be instinctively scared of gas itself like crushing devil. The truth is, and the video demonstrates it well, that gas itself cannot explode a house (gas leaking and fulfillment of exact conditions might maximum create a fire). It’s not a gas which explodes but cylinder which is extremely forbidden to keep in the house! Domestic cylinder should be kept outside because when the fire occurs a cylinder explodes turning into a bomb.
That’s why gas tanks are installed under the ground at settled distance from the house; moreover, cisterns are equipped with security valves.
