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Author Topic: Could small, compressible balls be used to negate the effects of ice expansion?  (Read 1648 times)

Offline McKay

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Hey, naked scientists. I am wondering about how to prevent freezing water from breaking its container (as it freezes). Of course, one way is to use anti-freeze of some sorts and not let it freeze in the first place, but, if I want it to still be drinkable, thats not really an option.

What I am pondering is - what if I fill the water container with some compressible balls (or cubes? Some other shape?), that would still be compressible at those temperatures, so they act as a pressure relief system of sorts. The freezing water/ ice would crush them instead of breaking its container.  Or coat the container walls of such material.
« Last Edit: 17/11/2015 08:11:46 by chris »


 

Offline alancalverd

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We do this to absorb the thermal expansion of oil in x-ray tube assemblies. The "absorber" is a small rubber bellows or ball filled with nitrogen that compresses as the oil expands.

This might work in principle with freezing water but you might need several balls as the water will freeze from the top downwards and thus trap a floating ball.

Alternatively put the water in a flexible bag inside a metal or glass bottle.
 
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Offline vhfpmr

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In general, I would have thought that simply leaving an air space would be enough, but it must depend on factors like the strength of the container, the pressure resisting expansion, and the friction between any ice already formed and the container.

Frozen milk manages to extrude itself out of the top of a bottle without breaking it, but a frozen water pipe often bursts.
 

Offline McKay

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Hmmm... so it might work. Ok, next question - how much does it actually expand? And, when it freezes from top- down, it tries to compress the still liquid water with each mm of ice more and more, so the buffer has to even larger, doesnt it?

Basically, I am planning to live in a motorhome in winter time. I can empty all the pipes so they dont burst, buy it would be a waste to dump all the water from the tanks. In case I leave the van un-heaed for a while and water starts to freeze. When I am back in the van and start up the heating system, the water would melt again and be usable.

Kinda ambitious.
« Last Edit: 15/11/2015 21:58:28 by McKay »
 

Offline wolfekeeper

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I saw a device for use in pipes; you put a long plastic pipe inside the copper pipe, and then when the water freezes it squeezes down on the plastic and the copper pipe doesn't burst.

I don't see why in principle you couldn't do the same with a tank. Perhaps just putting some weighted fizzy drink bottles, or something similar, into the tank might stop it bursting.

I don't know that it's guaranteed to work though; it may critically depend on how the crystal structure forms each time as to whether it pushes on the plastic bottles or on the sides- ice shove is quit an impressively powerful phenomena.
 
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Offline McKay

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I saw a device for use in pipes; you put a long plastic pipe inside the copper pipe, and then when the water freezes it squeezes down on the plastic and the copper pipe doesn't burst.



I cant seem to find such a thing. How is it called? In fact, I cant really find any solution that would be similar to this and even when I ask some people on the internet who live full time in motorhomes/ campervans, all I get is "Nop, just empty the pipes and tanks" or something on the lines.
 

Offline McKay

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Im thinking, perhaps something as simple as simple as  "unpopable" bubble wrap? How could that behave at freezing temperatures and those pressures?
 

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