Free pipe freezer

[Animal]

Would this work? Freeze a large amount of ice cubes. Place trays under the pipe, heap ice on & cover. If it does, it's free. I suspect it'd take too long to freeze.

[John Rumm]

Probably not going to be cold enough - especially with water under pressure.

[Steve Walker]

I don't know, but breaking up the ice a bit and adding salt will significantly lower the temperature - breaking it up to let the salt get to more surface area and the lowering of the melting point, due to the salt, causing the ice to melt, absorbing heat to do so and so cooling the pipe well below zero.

[nightjar]

Pipe freezer spray works by taking the temperature well below freezing; up to 60C below ambient.

[Brian Gaff (Sofa]

It would not work due to the low thermal conductivity, the ice would melt rather than the ice freeze the pipe., that is unless you have a free source of dry ice, which is a lot colder! Brian

[Martin Brown]

Not a chance.

However if you crushed the ice up a bit and mixed it with common salt of varying sizes then the resulting freezing mix will get down cold enough to freeze water even under pressure.

It is (very) old freezing technology for ice cream making.

Chloride ions can be corrosive and spoil solder joints though.

[Harry Bloomfield, Esq.]

Animal brought next idea :

No chance, unless hell freezes over too. Too make something freeze, what ever is doing the chilling needs to be well below zero C, to have any effect.

[newshound]

+1

[Max Demian]

Or add salt, as someone has suggested. People used to make ice cream, or at least water ice, using salt and ice save from winter before mechanical refrigeration.

Not quite sure why "Animal" wants to freeze a pipe, whether the water in it is flowing, or what is meant by "free".

[David]

I think that the ice cubes will still be just ice at usual temperature. Doesn't this strategy produce very cold liquid surrounding the ice? Thus the very cold liquid chills whatever is submerged in it, and the ice melts gradually to replenish the liquid?

If this is so the pipe would need to be immersed in a bath of cold water + ice to allow the super cold liquid (salt + water) to contact all of the pipe that is to be frozen.

Accepting that the ice itself will also be gradually chilled by being immersed in the super cold liquid.

Whatever, getting enough contact between the ice and the pipe would be difficult unless crushed ice was used.

You can tell my Physics O Level was a long time ago.

Cheers

Dave R

[Martin Brown]

Not quite. The salt is sufficient to melt the ice on contact - hence gritting of roads with rock salt. That dissolution requires energy so that the solution formed is a concentrated even colder brine. So long as there is undissolved salt and ice available it continues to get colder until it hits a limit determined by how cold the ice was to start with. Strong brine remains liquid at much lower temperatures.

If you start with ice that is far too cold it won't work as well (but that isn't likely to happen with domestic freezers).

It is sort of chemistry rather than physics.

[newshound]

He means he is not counting the cost of electricity.

[williamwright]

Maybe if you can get the ice down to -25C.

Bill

[alan_m]

Freezer spray can take the temperature down to -40/50C which I guess, with copper pipe, is required to freeze the water inside the pipe quickly enough so that heat from the rest of the (metres of) pipe melt it.

[Andrew]

Would a CO2 fire extinguisher work in an emergency (to freeze a pipe, not put out a fire)?

[Animal]

Perhaps if one were really organised the 2 might be combined. Spray the CO2 onto the pipe to cool it, then duct it to the fire to smother it. Then use the hot burnt things to solder the pipe.

[newshound]

Well the kit used by plumbers involves putting a length of insulation a bit more substantial than standard pipe insulation around the area of interest, and blasting in CO2 from a cylinder essentially identical to a CO2 extinguisher. You do need containment for efficiency though.