"Dave Liquorice" wrote in message
ll.net...
On Thu, 2 Oct 2008 22:29:23 +0100, dennis@home wrote:

You can probably get cold enough by mixing salt and crushed ice..

That mixture will hold fairly close to 0C

I suggest you try it.. It can get down to -8C with ease.

but will be pull heat from it's
surroundings whilst doing it. It might be able to freeze a pipe provided
you can ensuer that it is getting it's heat from the pipe and water rather
than the room in general. Certainly wouldn't be as quick as a proper pipe
freezer or the butane trick (that's for use in extremis only I think).

Pipe freezers also get heat from the surroundings, you need an insulated
container of some sort, e.g. tape a bag around the pipe and wrap it in cloth
to insulate it.