On the BIG-Chat list, we've been discussing what to do with the hazard represented by an unexploded pop bottle. They'll take (apparently) up to about 150psi before they burst, which they do with a hell of a bang, spinning shards of plastic, blood, gore, the usual. So: what happens if you have one sitting at, say, 130 psi, resolutely failing to explode but still, potentially, a bomb?
My suggestion is to equip a heavy radio-control car with a gas-powered soldering iron to melt the bottle side-wall. A comedy analogue of those army bomb-disposal robots.
Can I do this? Please?
; "Mosquito")
; "Damp feet")
;)
; "Iron")
; "project_sizes.png")
; "Photo-0076.jpg")
; "brian_on_newsnight.jpg")
; "Clock")
; "Laithwaite's_Ball.jpg")
.jpg',60,315,'gallery-item-10'); "Connection to government")
Count me in. Just as soon as I’ve finished the hovercraft.
Air rifle, Jon, air rifle.
Indeed, except that, as I posted to the group: “ricochets.”
Yow.
I knew that cordless soldering iron would come in useful. Although why not just a sharp thing?
PS line breaks don’t seem to work, even when I add BR tags manually…
Rats, it’s only the preview that doesn’t work.
How odd. I thought I had HTML turned off for comments. Harrumph, more experimentation needed.
Anyway: the problem, Harro, is what happens when you do steps 1 and 2 (with CO2 or liq.N2 in the bottle), but then step 3 involves plenty of ‘await’ and little to no ‘kaboom.’ How do you safely defuse one of these things?
Rosie’s right that a sharp point should do the job, but the bottle sidewalls are surprisingly strong, and I worry that you’d have to ram the bottle rather hard. And let’s remember that the bottles are full of gas, not liquid - they’re very light.
Hence a soldering iron on a slow but manoeuvrable tank-like contraption. Less dramatic but more reliable, I’d wager.
PS. I see what you mean about the preview, Harro. Bleurgh.
I’d expect that with liquid nitrogen, the bottle would become brittle, and shatter at much lower pressure.
Except … handling and storage of N2(l) is not trivial. H&S would have a barney.
Unless of course you’re already using it for other stuff.
In very small quantities for demonstration use it’s really not that bad. The biggest problem in those circumstances is transport, since the only real option is loosely-stoppered Thermos flasks wedged so they really really really can’t fall over in your car. Which is more than a little hairy, frankly.
But it’s not clear what the alternative is. I did once risk-assess transport of a small wheeled storage dewar, but the implications of an accident involving a Transit van and that amount of N2(l) are, I reckon, rather worse than a litre or so in a Thermos in a Volvo.
The problem is no so much the liquid, but the vapour.
It’s something outrageous like 1 ml liquid displaces 22 l air, so ‘lossely-stoppered’ Thermoses (?) are more dangerous than tightly-stoppered ones. At least in an accident you might expect that the nitro would be dispersed pretty quickly to atmosphere: your car is a much more confined space. You fall asleep, and never wake up
“loosely”. Gah.
Hell, no! A tightly-stoppered Thermos full of N2(l) is exactly the sort of bomb I was writing about in the main post.
You’re right that ventilation is required, but never, ever, seal a container of liquid nitrogen without decent pressure relief.
All our flasks /have/ loose lids, but we don’t carry them in cars!
sorry, I hit post by accident. I meant to add that proper flasks with the appropriate pressure relief are not horrendously expensive, and are unlikely to fall over.