Quantcast

I am totally fascinated...

Help Support Plumbing Forums:

Mitchell-DIY-Guy

Well-Known Member
Joined
Oct 16, 2019
Messages
238
Reaction score
67
Location
North Carolina
Coming from a land where you design things to PREVENT pipes from freezing, and frozen pipes "are a thing" and cause of many issues, imagine my surprise when I discovered a crew INTENTIONALLY freezing a pipe at my home yesterday.

The contractors for the City of Charlotte came by to add a box for a new irrigation meter. This "Tees" off the house water line, before the existing meter. Well, the water system design here doesn't have any shutoffs at the main or anywhere before the meter; the only shutoff is integral to the meter. So, how do they "shut the water off" so they can add a Tee? They freeze it.


Once frozen they had about 5 minutes to cut and splice in the Tee. You learn something new every day!
 

havasu

Administrator
Staff member
Admin
Joined
Jan 5, 2010
Messages
9,666
Reaction score
1,450
Location
Southern California,
Freezing pipes to stop water flow has been discussed in here occasionally. I too am amazed at how well it works.
 

Birkoff

Member
Joined
Sep 26, 2012
Messages
11
Reaction score
0
Location
,
There is a recent episode on This Old House where they demonstrate the 'why' behind typical household freezing pipe. Its not the water. Its the air pressure. Which is why 'dripping' works because it release the air pressure build up.

Things they never taught you in Physics class.
 

Dan the Plumber

Active Member
Joined
Aug 31, 2019
Messages
29
Reaction score
13
Location
95404
Doesn't make sense. Air has the ability to expand, water doesn't. You sure they were not talking about water pressure as opposed to air pressure?
How you gonna get AIR pressure inside your water pipe? Yes, fluids don't compress or expand, until they change to a solid. In this case water to ice. Running a drip merely keeps the water from freezing.
 

Mitchell-DIY-Guy

Well-Known Member
Joined
Oct 16, 2019
Messages
238
Reaction score
67
Location
North Carolina
Domestic water, whether from a pump (well) or city sourced, is fairly consistent in temperature, adjusting for season and geography. Say, 50 degrees. But, water has to be 32 and below in order to freeze. If you are dripping water out of a faucet in a freezing environment, you are displacing water at or about to freeze, with "warm" water at 50 degrees. THAT'S why a dripping faucet won't freeze.

I have not heard of anything to do with air pressure; I suspect that Birkoff misunderstood This Old House's demonstration. What they said was that when a length of pipe freezes--i.e. a slug of water in a pipe (remember there's rarely air in a pressurized water system) gets frozen, that water expands by 9%. That ice (not air) exerts pressure on the rest of the water in the system. Water won't compress; so now this highly pressurized water is finding the weak spot in the system and will cause a pipe to split, a joint to open or a valve to crack.

You can prevent this by providing a path for the water to go. Turning off water at the main, or turning your well pump off and depressurizing your system and leaving faucets open will prevent most bursts from freezing, as the ice in the pipe will push the water out the open faucets rather than crack a pipe or valve.
 

Riickk

Well-Known Member
Joined
Nov 14, 2019
Messages
186
Reaction score
54
Location
Delaware
And not all liquids e x p a n d when they freeze, in fact, water is one of the very few that expand, most contract.
 

Nukedaddy

Well-Known Member
Joined
Oct 21, 2013
Messages
56
Reaction score
12
Location
St. Louis, IL
The answers above hit on many of the “truths” about water. Here are some tabulated facts:
Water is at its densest at 4 degrees C. It expands at temperatures both above and below 4 degrees.
Anything added to water, be it sodium from softeners, chlorine, calcium or air will raise the boiling point and lower the freezing point. But the temperature of maximum density is unchanged.
While it is true that liquid water is considered as a non compressible fluid, that is not exactly true. It is “practically” non compressible. Consider: You have a tank that is full to the brim with water. No air, no empty spaces inside. You have a gauge connected to the tank. You want to raise the pressure in the tank to 1000 psi.How? The tank is already full! Well, the deal is you have to add more water. Not very much at all, but yes, water is slightly compressible.
You can freeze water in a pipe as described above with no damage easily. You must: Make sure that the freeze plug is far enough from a dead end of the line so that the “slightly compressible” property can absorb the pressure produced by the freezing water. It is this effect that in northern climates cause frozen pipes to burst near the ends of fixture branches. (Air chambers do not protect these branches because they “waterlogged” by dissolving the air trapped in them)
Two ice plugs near each other will almost always burst the pipe.
 

Pat the Plumber CIL

Professional
Professional
Joined
Apr 23, 2020
Messages
62
Reaction score
37
Location
Springfield , Il
I own a Rigid pipe freezing machine , have not used it as much as I would have thought . Heavy and need a straight length of pipe to connect it to . Thought about the gas system but hate to refill bottles . It has worked well but it has split a pipe once in about 20 times I have used it . . Good to have a back up plan if you want to use it .
 
Top