On Sun, 5 Oct 2008 10:28:49 -0700, "Big Al"
wrote:


"Richard Evans" wrote in message
.. .
Blattus Slafaly wrote:

jack wrote:
I have had burst pipes, so I know it happens.

Just as an experiment I took 8" of 1/2" copper and capped one end. I
filled
it with cold water and stuck it in my freezer.
After 30 minutes it was somewhat frozen, and solid after an hour. But 4
hours later it hasn't burst.

So, why do some pipes burst, but not this one? The ice expanded out the
top, so it definitely expanded. Perhaps it has to be physically
prevented
from expanding with a right angle piece at the top?

(My cottage has exposed copper pipes and no heat, and I try to avoid
draining them until necessary. When the temperature gets down there I
get
antsy. I am experimenting to get a better idea of just what the danger
really is.)


Cap both ends and try it again.

FWIW, in 1984 I moved to West Palm Beach, FL. The incoming water line
was completely exposed for about three feet where it came up the
outside of the house. Wouldnt'cha know it, my first night there they
had a hard freeze, temp down to 22 degrees. The exposed line froze,
but did not break. Presumably, that would count as having both ends
capped.

Presumably not Water can go back into the main.

Yeah, I think the pressure of expanding ice is greater than the water
pressure in the main.

And I can prove it.

The pressure of expanding ice is greater than the strength of copper
water pipes, or the pipes would not burst when the water freezes.

The strength of the copper water pipes is greater than the water
pressure in the main, or the normal water pressure would cause the
water pipes to burst.

So the pressure of expanding ice is greater than the pressure in the
main.

Al