dlramp4life
Topic Author
Posts: 994
Joined: Sat Jun 25, 2011 6:23 pm

Draining Water Tanks

Wed Jan 16, 2013 6:59 am

Since the weather has gotton below freezing every night for the past week where I live, we have been instructed to drain water tanks on all aircraft that won't be sitting at a gate connected to power all night...

My question is if there is power from a GPU going into the aircraft, how the plane having power does prevent the water from freezing over in potable water tank?
SEA Ramp, wettest place on earth
 
Bartonsayswhat
Posts: 353
Joined: Sun Oct 28, 2007 8:42 am

RE: Draining Water Tanks

Wed Jan 16, 2013 9:23 am

Water tanks are heated. Our ground manual (CRJ200) tells us to to ensure RON aircraft are plugged in overnight, ground service switch is on, and that the water system power switches in the galley are on. This ensures the heater ribbons are turned on. SOP is to take a diesel GPU out to the plane and keep the heaters on rather than drain the system, as not all of the water from the lines will come out and cracking in the lines could occur.
 
Tristarsteve
Posts: 3359
Joined: Tue Nov 22, 2005 11:04 pm

RE: Draining Water Tanks

Wed Jan 16, 2013 10:22 am

Quoting bartonsayswhat (Reply 1):
Water tanks are heated.

I see you live in Canada. Maybe your water tanks are heated. It is not normal.
Standard aircraft have no heating at all for the water system. Water line heating with electric ribbon heaters is an option that is only taken up by airliners in arctic regions. The rest of us drain the tanks.
I find that with an A320, putting a cabin heater on will keep the water flowing down to around Minus 20 degC overnight. Putting on ground power has no effect at all.
The rules here are, down to M5degC do nothing.
M5 down to M15 put on cabin heater
M15 down, drain water system.
 
dlramp4life
Topic Author
Posts: 994
Joined: Sat Jun 25, 2011 6:23 pm

RE: Draining Water Tanks

Wed Jan 16, 2013 8:46 pm

Quoting bartonsayswhat (Reply 1):

I find that interesting because we have a CRJ700/900 over night in my station daily and the regional airline policy states that we drain the tanks when the aircraft is a RON.
SEA Ramp, wettest place on earth
 
AA737-823
Posts: 4889
Joined: Wed Mar 01, 2000 11:10 am

RE: Draining Water Tanks

Thu Jan 17, 2013 10:47 pm

Quoting dlramp4life (Thread starter):
My question is if there is power from a GPU going into the aircraft, how the plane having power does prevent the water from freezing over in potable water tank?

Even a powered airplane makes a bit of heat. We tried this approach once. Once.

Quoting bartonsayswhat (Reply 1):

Water tanks are heated.

No, not really. The water lines are optionally heated; the tank is not.

Quoting bartonsayswhat (Reply 1):
This ensures the heater ribbons are turned on.

Exactly; the ribbons heat the lines, not the tank. I'm not aware of any aircraft that has optional tank heat.

Quoting bartonsayswhat (Reply 1):
as not all of the water from the lines will come out and cracking in the lines could occur.

Not if it's designed properly. When rampers drain the potable tank, they're not getting the water out of the system, sure. But when we mechanics do it, we know to open the OTHER drain valve, which lets the remainder of the water gravity feed out of the system's lowest point.

Quoting Tristarsteve (Reply 2):
I see you live in Canada. Maybe your water tanks are heated. It is not normal.

I doubt it; here in Alaska, the 737 tanks aren't heated... just the lines.

Quoting Tristarsteve (Reply 2):
The rest of us drain the tanks.

After learning the hard way that forward lavatory lines are VERY HARD TO THAW, we leave heat on the planes, and drain the water anyway! If someone (ramp) leaves L1 cocked while they are servicing the cabin, the door hinge covers aren't sealed shut, and blow icy air straight into the forward lav cavity that houses the water line! Took us ages to figure that one out.

All of this is why I eagerly await the arrival of May, when temps no longer warrant potable water worries!
 
Tristarsteve
Posts: 3359
Joined: Tue Nov 22, 2005 11:04 pm

RE: Draining Water Tanks

Fri Jan 18, 2013 7:56 am

Quoting AA737-823 (Reply 4):
All of this is why I eagerly await the arrival of May, when temps no longer warrant potable water worries!

Yes, the amount of problems drinking water supply on aircraft causes is amazing.
We need someone to invent an additive that stops water freezing, and can be drunk!
 
rwessel
Posts: 2448
Joined: Tue Jan 16, 2007 3:47 pm

RE: Draining Water Tanks

Fri Jan 18, 2013 7:59 am

Quoting Tristarsteve (Reply 5):
Yes, the amount of problems drinking water supply on aircraft causes is amazing.
We need someone to invent an additive that stops water freezing, and can be drunk

100 proof vodka freezes at about -40 (F or C). And it can be drunk.   
 
Bartonsayswhat
Posts: 353
Joined: Sun Oct 28, 2007 8:42 am

RE: Draining Water Tanks

Fri Jan 18, 2013 9:21 am

Quoting AA737-823 (Reply 4):
The water lines are optionally heated; the tank is not.

Just look at the winter ops chapter in our ASM, and it only mentions to make sure the ribbons are just turned on, I guess I always just imagined them in the tank. It says water MUST be serviced full, as the lines on the CRJ don't completely drain. Also service lavs full with Type 1 glycol 100% and a cup of undiluted deodorant liquid, or 50-50 automotive anti freeze.

If it gets below -25 and the A/C RONs outside, then the covers go on, and a heater unit must be attached. If heater is unavailable, then the APU is run and the plane is babysat..

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