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Draining Water Tanks  
User currently offlinedlramp4life From United States of America, joined Jun 2011, 961 posts, RR: 1
Posted (1 year 10 months 2 weeks 2 days 13 hours ago) and read 3085 times:

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?


PHX Ramp, hottest place on earth
7 replies: All unread, jump to last
 
User currently offlinebartonsayswhat From Canada, joined Oct 2007, 436 posts, RR: 0
Reply 1, posted (1 year 10 months 2 weeks 2 days 11 hours ago) and read 3049 times:

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.

User currently offlineTristarsteve From Sweden, joined Nov 2005, 4053 posts, RR: 33
Reply 2, posted (1 year 10 months 2 weeks 2 days 10 hours ago) and read 3030 times:

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.


User currently offlinedlramp4life From United States of America, joined Jun 2011, 961 posts, RR: 1
Reply 3, posted (1 year 10 months 2 weeks 2 days ago) and read 2878 times:

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.



PHX Ramp, hottest place on earth
User currently offlineAA737-823 From United States of America, joined Mar 2000, 5915 posts, RR: 11
Reply 4, posted (1 year 10 months 2 weeks 22 hours ago) and read 2680 times:

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!


User currently offlineTristarsteve From Sweden, joined Nov 2005, 4053 posts, RR: 33
Reply 5, posted (1 year 10 months 2 weeks 12 hours ago) and read 2604 times:

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!


User currently offlinerwessel From United States of America, joined Jan 2007, 2392 posts, RR: 2
Reply 6, posted (1 year 10 months 2 weeks 12 hours ago) and read 2601 times:
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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.   


User currently offlinebartonsayswhat From Canada, joined Oct 2007, 436 posts, RR: 0
Reply 7, posted (1 year 10 months 2 weeks 11 hours ago) and read 2577 times:

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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