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Post by jonjel on Mar 13, 2018 12:08:14 GMT 1
One of my people here is a retained fireman. I agreed he could do that a few months ago. And he was called out on 'a shout' last week.
The incident was an explosion reported in a local corporate place and I won't give too much detail here. When they got there they found that a hot water cylinder, just a single skin copper cylinder of around 200 litres had exploded. I assume that the vent had jammed and maybe the immersion heater had just carried on cooking the contents until it went bang.
However the damage was awesome. The outside wall adjacent to the tank had deformed to the extent that a large stone lintel had been moved around 150mm outwards, together with stones and bricks and the wall the other end of the corridor around 20 metres away was also deformed. How anyone was not killed is a miracle.
Now I was thinking about this. My physics is rusty but I seem to remember that 'a mass of gas expands by 1/273rd of it's initial volume per degree centigrade rise in temperature' So just how hot would that tank have too have got to do that sort of damage?
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Post by alancalverd on Mar 14, 2018 9:29:36 GMT 1
What matters here is the amount of energy stored in the gas. 200 litres of water requires 452 MJ of energy to evaporate at 100 deg C, equivalent to the energy content of 10 kg of diesel fuel. That would indeed make a hell of a big bang.
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Post by jonjel on Mar 14, 2018 11:21:54 GMT 1
Thank you Alan. I suppose we all think of 'an explosion' as something which has a shock wave travelling at high speed. But enough puff in effectively a confined space will blow the house down!
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Post by alancalverd on Mar 14, 2018 17:35:18 GMT 1
"Exploding boilers" were all the rage in the early days of steam locomotives and even electricity generation, to the point that even nuclear power stations are required to have oldfashioned water level and steam pressure gauges, and a pressure relief valve - the latter tied down in all the best Western train heist movies.
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Post by mrsonde on Mar 14, 2018 17:49:35 GMT 1
Reminds me of the famous Tunguska explosion of 19O8, said by people of Aqua's persuasion to have been caused by a crashed UFO, on a mission to anally probe communist fomenters, because of the rumour they put up the least resistance (to each according to his need.) Turns out, as BuzzFeed investigative journalists recently revealed, it was merely a samovar whose spout had got blocked with yak shit.
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Post by jonjel on Mar 15, 2018 11:55:12 GMT 1
I had a friend who was cooking with his daughter prior to Christmas as his wife was ill. As luck would have it someone came to the door and he and his daughter left the kitchen. There was an enormous explosion behind them. The ham in the pressure cooker had risen to the top and blocked the steam vent. The plate rack on the cooker was all twisted out of shape, the window was blown out and other damage. His wife made a miraculous recovery!
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Post by mrsonde on Mar 16, 2018 19:05:49 GMT 1
Ah, that takes me back to a similar experience, as a tearaway teen exploring...exploring...ways to get out of my head, mainly. Had my mother's Prestige pressure cooker converted into a primitive still, the aim being to render the village's opium poppy supply into something more palatable and potent to imbibe than the appalling opium tea I'd probably been enjoying too much hitherto. Reader, it didn't work. The whole jitchen bepslattered by literally milions of opium poppy seeds, and green sludge, and the most appalling rotten vegetable stench - cabbage and sprouts has nothing on it. Parents due home in less than two hours...Luckily, in those days, before the internet, digital cameras, and video games, you could select a Fast Forward function in your motor cortex, and perform what the idle bastard kids these days would consider miracles.
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