Water Freezing

[PTHutch]

How’s your chemistry knowledge?
Does anyone know if a bleach-water mixture will raise the freezing point of water?

I was sanitizing the water system of our Sunline yesterday with a bleach-water mixture. The temps were forecasted to drop below freezing last night so I decided to blew out the lines after sanitizing the system.

When I drained the black tank a frozen log came out where the bleach-water mixture had solidified within the outlet pipe of the tank. This happened round 7pm last night and the temps were above freezing (37-40 degrees). After I saw this I decided I better put anti-freeze down the drain pipes and in the tanks also.

But I’m trying to figure out what caused the water to start to freeze. It was only in the pipe for a couple of hours and the temps were above freezing.

Was it the addition of bleach to the water that caused it to freeze at higher temps?
Or did it have something to do with the 3” black tank pipe?
The bleach-water mixture didn’t freeze in either gray tank outlets (our T-280SR has 2 gray tanks – galley & bath).

It’s a mystery to me!

Any thoughts or ideas?
Hutch

[MACK C-85]

Did you drain the black tank before adding the bleach solution? The "log" may have formed from left over water during the winter, and thawed enough to come out now?? Just a thought.

[PTHutch]

Hi Mack

Good throught, but I drained all tanks prior to this so it wasn’t from a winter freeze. Plus the tanks had anti-freeze in them over the winter, which I had drained out earlier in the day.

What I did yesterday was fill the fresh water tank with water bleach mixture and ran it through all the water lines, purging the lines of anti-freeze and filled the HW tank with water-bleach mixture.
Then I emptied the black and gray tanks to empty them of winter anti-freeze and the water-bleach mixture put in them from the sanitizing process.

So the black and gray tanks were empty when I blew out the water lines. The water that was in the black tank and froze was only from blowing out the water lines.

Interesting huh!?

The other thought I had was I use a small compressor to blow air through the city water intake to blow out the lines. Could that forced air add some additional cooling affect to the water?

Hutch

[wcoleman]

Bleach would actually lower the freezing point of the water you added it to...pure bleach freezes well below the freezing pt. of water.

Wayne