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Old 8th Dec 2012, 20:14   #1 (permalink)
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Can water pipes freeze

Quick, and possibly silly, question...Can the water pipes on an aircraft freeze without bursting? Specifically on a 757 with regard to the coffee makers.

I've been on flights where the coffee makers will stop working. Usually happens if they've been off for a while (say a few hours) and when you turn it on, nothing. Won't brew. Friends say the pipes freeze and you should leave the makers on continuously. I say no because the pipes would burst if the water inside froze.

Oh yes, there is always water in the tank so that's not the issue.

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Old 9th Dec 2012, 03:28   #2 (permalink)
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i have seen burst water pipes, that's why we drain the water on cold layovers
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Old 9th Dec 2012, 03:41   #3 (permalink)
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No, the water pipes aren't likely to freeze. However' the water inside the pipes will begin to freeze if the temperature drops to, or below, zero degrees celcius. If the water freezes completely, as in "frozen solid" it will indeed burst the pipes. If, however, the water only partially freezes, it will turn to a consistency of "slush" that will be less likely to flow as would otherwise be expected.
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Old 9th Dec 2012, 04:22   #4 (permalink)
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There are many reasons why a coffee maker will not brew. Frozen water in the pipes is one reason, slush too can block the lines.

You need many things to happen for the coffee maker to work. Power, if the utility buss (can be switched off in the flight deck) or external power can trip off no coffee. If you do have power, if there is no water in the coffee maker, usually, there is a light on the coffee maker warning of no water. There is also over heat protection built into the coffee maker, much like your coffee maker at home, if the coffee maker is empty, it may trip the overheat protection and the coffee maker will not work. Unlike you coffee maker will not reset on it's own. Someone will have to remove the coffee maker and reset the overheat protection switch.

With no APU or engines running there is no air pressure to the water tank, the water tank needs air pressure to pressurize the tank to push the water through the pipes to the coffee maker.

The water lines between the coffee maker and water tank, usually below the floor, could be empty. So if the lines are empty, you will need to hold the water faucet open until the water from the tank, being pushed by the air pressure on top of the water inside the tank travels through the lines to the coffee maker. Further, even if the APU is running or the engines are running, if he water lines are empty, the air in the lines has to be bled out before the coffee maker will work. The air will prevent the water from flowing unless there is opening for the air to escape, usually the faucet. If you hold down the faucet, you should here the air escaping, this is a good sign and if you are patient and continue to hold the faucet open, the water will eventually arrive.

A good example if this is when you buy a new garden hose. You hook up one end of the garden hose to the water faucet, when you turn on the spray nozzle at the other end of the brand new hose, you do not get water coming out of the hose immediately. You must hold the water nozzle open until the water pressure pushes all the air out of the new hose before the water will flow.

All these instructions are assuming that the water system is intact and serviceable.

Pipes do freeze, even if the pipes have heating ribbons installed, this system is not perfect and sometimes gets disturbed during maintenance. The pipes can burst and do occasionally.

Anytime you are outside the aircraft in freezing weather, look at the fuselage bottom at the 6 o'clock position, if there are icicles hanging from the fuselage drain valves, these will close once the fuselage is pressurized, you can be almost sure that a water line is leaking or worse, burst from freezing.

If this happens close to departure time, we would usually deactivate and drain the water system, we then call for bottles water and hand wipes for the lavs. We would also call the kitchens to supply thermos' full of coffee. Not too many airlines want to take a delay for this. This will continue all day until the next hangar visit, hopefully the aircraft is rerouted to a hangar layover to repair this.
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Old 9th Dec 2012, 05:32   #5 (permalink)
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Thanks for all the info. I appreciate it.

Quick follow up...are the pipes usually flex-hose type or a kind of pvc?

Thanks again.
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Old 9th Dec 2012, 06:42   #6 (permalink)
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The pipes that immediately connect to a coffee maker maybe flexible and/or braided pipes, these should not freeze, the only pipes that are likely to freeze are those that lead to the drain masts, should the heater blankets not be working, the masts are also heated, have a look outside next time you will see them they usually have CAUTION HOT painted on them!
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Old 9th Dec 2012, 06:46   #7 (permalink)
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It's been a while since I last battered one back to life, the the CB's on bev.makers were, and probably still are, "tempermental" and prone to tripping with minimal overload. I would always look at these first therefore.

On the other hand, human factors can play a part.

Called to the rear galley for an "emergency ! " just prior to push back. Arrive to encounter "madam" who duly launches into a "what sort of customer service is this !..was I the engineer responsible !..how dare I provide this level of service for customers"...etc, etc. and all within earshot of the pax.

One waited and duly opined that, whilst one was merely a "thick engineer" said with suitable sarcastic inflection, one wondered if "madam" had studied English and Physics at school by any remote chance ?..if so, "madam" would have noted, as one kindly demonstrated, that if she moved the water supply knob from, erm, "Closed" to "Open, then, oh look, water doth flow!.

Less than muffled laughter from the adjacent pax and a few smiles as I left the galley.
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Old 9th Dec 2012, 22:17   #8 (permalink)
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The described symptoms do suggest the pipes are freezing. This is actually quite a common defect which I have seen before on the 757 amongst others. The usual cause of this it when the pipes pass too close to the skin of the aircraft when the insulation blankets haven't been fitted correctly. Indeed, this will most commonly show during cruise when the boilers might not be used often, ie positioning flights when the boilers are only used for the occasional crew cuppa.
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Old 10th Dec 2012, 04:15   #9 (permalink)
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Drinks taste funny at cruise,That was a squawk on a G III, From the head overflow to the Ice bucket, Drinks taste funny.... Iced drain mast
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Old 11th Dec 2012, 16:43   #10 (permalink)
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Material of water pipes

Water pipes are mainly made of stainless steel and have flared ends.
You put a conical ring in between to seal and they are held together by a plastic clamp!
In case of icing up, the line expands and breaks the plastic clamp!
You install a new clamp and there is only little damage....
Cheers easaman
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