Monday, December 10, 2012

Why pipes freeze when the hose is attached.

Why pipes freeze when the hose is attached.

November in Kansas was unseasonably warm. Most days the temperature rose into the sixties, sometimes even into the seventies. People walked around in shorts, t-shirts, and tennies saying things like, "If this is Global Warming, I'm all for it," or "Living in L.A.." Even into the first week of December, it seemed as if summer had lingered a bit too long.

Perhaps, to Al Gore's relief, the weather finally turned cold. The temperature last night dipped down into the low teens and for the first time, and the weatherman was using the words "frigid" and "wind chill".

The Old Man's wife came home late last night. Dressed in pajamas and shoeless, he was ordered out of the house and told to unhook the hose from the faucet.  "If you don't, the pipes will surely freeze," she said knowingly.

The Old Man is a skeptic, not a cynic, mind you, just a skeptic. There is a difference. So, he said, "Can't be!" It was not just because he did not want to go out in the chilly night air and wrestle with two hoses, it was because he truly didn't think water could freeze all the way to the interior pipes of the house and burst.

After minding the wife and disconnecting the hoses, the skeptic went to Googe for an answer. Not surprising was that everyone repeated the mantra that one has to disconnect a hose or a pipe will freeze and burst. What was surprising was that no one explained why.

Was it just an Urban Myth cooked up by wives to get their husbands out of bed and out in the cold?

Water is one of those molecules that has an unusual property. Freeze most things and they contract. Any guy standing out in the cold North Wind notices this phenomenon with parts of his body. Not so with water, freeze it and the molecules form a pattern that actually increases the volume of a given mass. This is why ice cubes float, why pot holes show up, why icebergs sink ships, and why, if the polar ice caps melted, Florida would be under water.

The skeptical Old Man googled the volume of ice compared to water. It turns out that ice has about one-tenth more volume than water. Here's what the chemistry experts at Elmhurst College say:

Elmhurst College, Illinois

Which is more dense - Ice or Liquid Water?
"The increase in volume of ice is about 9%. This increase causes enough force to break most rigid containers. This is the same force, repeated on a daily basis, that creates "pot holes" in the roads in the winter time."
Of course, the Old Man's wife knew already that the Old Man was denser than both water and ice. The Old Man needed proof. How could a hose, turned off at the faucet, have enough water to expand and reach inside the house, bursting pipes and making plumbers all over the America rich? Scientific fact or nefarious housewives' plot.

Let's think about it. Take a 50 foot hose that attaches to a faucet 2 feet off the ground. Turn the water off at the faucet and one would expect that, all things being equal, the water in the hose would drain out if it was on a down hill incline. But, if the hose was attached to a sprinkler or a nozzle or if the hose was on an uphill incline, then one would expect the hose to be chock full of water. This is something the Old Man verified as he unscrewed the hoses from the faucets.

Now, the Old Man could calculate the volume of the hose, but it the answer comes out the same if we just use the length of the hose as a measurement. Assuming, for argument sake that 2 feet of hose is empty (the distance from faucet to ground) that leaves 48 feet full of liquid water.

That is a hose that is 96% full of water, or more than enough to burst anyone's pipe.

Now the Old Man was out to dinner the other night when his wife gave him some bubble gum with the following message on the package, "Let's just assume I am right."

Following this advice would have saved the Old Man some time and worry.

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