View Full Version : Jet venting liquid overboard.
Hello All,
Was paxing in an A320 yesterday between Hobart and Melbourne and musing about some of the jets I have flown in (as pax only) and this thought bounced around my head for a while:
Do big jets vent any liquid while in flight? Do they for example vent the water from the hand basins overboard?
The reason for the question is simply because I imagine aircraft performance would be improved slightly as weight is jettisoned overboard?:8
Cheers.
Intruder
8th Oct 2007, 02:59
Yes, the sink drains vent overboard.
Thanks Intruder,:ok:
I thought that must be the case, as the staff don't like anyone going to the toilet while the aircraft is on the ground - yesterday they became very insistent that some poor sod return to his seat during boarding and not use the loo while on ground.:ooh:
Do RPT aircraft vent any other liquids overboard during flight?
Thanks again mate.
Cheers.
Any fluids dumped into the sinks either in the toilets or galleys is jetissoned overboard. A far as I am aware, in normal operations, thats it.
What is the reason for venting sink fluids overboard instead of sending them to the sewer holding tank?
Is it as I suppose because sink waste is relatively clean and easy to dispose of (may evaporate or break up before hitting the ground) and will deliver minor performance gains?
Cheers.
spannersatcx
8th Oct 2007, 07:04
yesterday they became very insistent that some poor sod return to his seat during boarding and not use the loo while on ground Unless it's a security thing, as I see no reason why toilets can not be used otherwise, we certainly don't stop there use.
Anyway I bet the CC were pouring liquid down the sinks in the galleys, which ends up in the same place as hand basin water.
As said above, the water gets drained out through drainpipes under the aircraft. On windy days this drained water will get spraid into the faces of the ramp personell. Maybe that's the reason...
Where does the waste fluid exit the aircraft? I imagine underneath and to the rear?
Rainboe
8th Oct 2007, 08:43
It was to get the buggers to sit down and not disrupt the loading process by trying to move forward back to his seat agaisnst the flow of people boarding, and to ensure should there need to be a head count he was included.
Sink fluids are vented overboard from heated mast projections. Not for economy, weight loss is negligible. Toilet drain wagons remove all other waste. It costs. Why unnecessarily add a lot more relatively clean fluid to it?
zerozero
8th Oct 2007, 17:41
I agree there is no weight issue but as with everything else in airplane design, physical space and capacity can become critical issues.
Why take up space in the toilet tank with soapy water and old coffee? Better to jettison that stuff and save the space for the real vile stuff.
ABX--sounds like the cabin crew were just being snooty about using the lavs on the ground and getting in their way. They can be like that.
True, the sink liquids get drained out of a heated mast. On the ground they just drain on to the ramp. In flight, at *very* cold temperatures, most likely, it vaporizes.
Brian Abraham
9th Oct 2007, 01:54
How much water is carried? Imagine a 747 long haul its quite a bit and not an insignificant percentage of gross.
mitzy69
9th Oct 2007, 10:47
I believe the Comet had sinks basins draining into a tank, and was emptied on the ground like the toilet waste.
Water potable can be 1 ton, 1000 litres, on B747 B777.
NutLoose
9th Oct 2007, 11:51
ABX
Where does the waste fluid exit the aircraft? I imagine underneath and to the rear?
This picture shows you the drains, the HOT is because they are heated inflight to stop them freezing up and blocking
http://www.b737.org.uk/whiteice.htm
you will also find a lot more of interest on the site, please visit www.b737.org.uk (http://www.b737.org.uk)
Rainboe
9th Oct 2007, 12:07
Now here's a big secret in aviation nobody tells you: into the toilets you throw blue sterising tablets to make the lavatory water a pretty shade of blue. Sometimes (actually quite often), the valve underneath the aeroplane where the toilets get emptied (a large pipe behind a hinged panel) leaks inflight. It works its way out of the panel (not airtight), and promptly freezes as it builds up. Eventually when the vibration loosens it, or it starts melting during descent, this rather large block of ice breaks off and falls away. It always seems to fall onto some Granny's house, burst through their ceiling and sit on their carpet. Granny is mightily impressed that this large pretty blue block of ice has fallen from the sky, and thinks it had better be kept for study by someone, so what does she do? She puts it in a large polythene bag, sometimes that one that her coat came back from the dry cleaners in if it's too big, and puts it in her freezer! In aviation, we have a term for this- a nice pretty name......Blue Ice. Google it if you don't believe me.
aw8565
9th Oct 2007, 12:49
Does this make you feel guilty Rainboe!?
http://uk.youtube.com/watch?v=czvF3HfJTLQ
Rainboe
9th Oct 2007, 13:02
"I never had nuthn' like this happen to ma in my whole life!"........er yes, one sincerely hopes one doesn't attract large 50 pound blocks of frozen sewerage falling on one's head more than once in a lifetime!
Couldn't stop laughing at the naivety of everyone! Er...yes....I feel sincerely guilty!
Great link NutLoose, that website is an interesting read.:ok:
forget
10th Oct 2007, 11:07
This'll take Rainboe's mind off Blue Ice. ;)
http://i21.photobucket.com/albums/b270/cumpas/hanger.jpg
Can anyone give me the fresh water capacity of their current aircraft?
For example, the A320 I was paxing on last Sunday would only hold a couple of hundred liters or so would it not?
Cheers
Wodrick
10th Oct 2007, 14:01
Good guess ! Potable water tank capacity A320 200 Ltr
Thanks Wodrick,
Maybe a 744 driver can tell me how much potable water is carried on board, is it the same as the classic?
How about the A380, anyone know?
Any other large aircraft?
Cheers
CV880
11th Oct 2007, 17:55
744 normally has 3 water tanks of 100 US gallons each = 300 gal. There is an option to have 4 tanks as some operators flying very long flights or those with humidifiers installed found they got very low on water with 3 tanks.
Capt Claret
11th Oct 2007, 23:18
The B717-200 has a 47 gallon (US)/177.9 litre potable water tank, two or three lavatories. All potable water from the galley sink and lav washbasins vents overboard and evaporates into the atmosphere. This venting has been used to signal to under flying aircraft, from time to time. :E
Ramp personnel have been known to walk off the job if the lav (vacuum system) is flushed, as they claim the vacuum system exhaust, which vents near the aft baggage hold is not pleasant to experience. After 20 mins, the air has cleared and they resume duties. Perhaps this is a reason for not allowing lav use on the ground.
CV880 about 1000 - 1400 liters then. Thanks.:ok:
LOL Capt. Claret,
I presume the under flying aircraft gets a wet windscreen?
Thanks for the info & story.
Cheers
SLFguy
13th Oct 2007, 06:52
I take it we should pi$$ in the sink when over France then.....:rolleyes:
Capt Claret
13th Oct 2007, 13:14
ABX,
The closest separation I've seen when the signalling had been done is 1000'. One can see the mist evacuate from the bottom of the aircraft but it dissipates within seconds. I doubt that it wet anything.
zerozero
14th Oct 2007, 00:09
The closest separation I've seen when the signalling had been done is 1000'. One can see the mist evacuate from the bottom of the aircraft but it dissipates within seconds. I doubt that it wet anything.
Slight tangent:
During my first winter in Alaska, when it was really cold (-40C) and we got really bored, we'd boil a pot of water, take it outside and throw it into the air.
Guess what happened?
None of the water ever reached the ground. It just went <poof> and vaporized (turned to steam).
Fun times!
I'd guess it's the same thing when we wash our hands in the lav. The waste water is heated (probably not to 100C) but when it reaches the frigid slipstream (~-50C) I'm willing to bet it just turns to steam as well.
:8
Green Guard
15th Oct 2007, 07:40
willing to bet it just turns to steam as well.
O no no. Not the steam. Steamy dust ?
Maybe !
Trying to shake the dust of the old brain here and remember high school science classes::8
Water will boil at a lower temperature in a lower pressure environment, right?:\
If that is right then I postulate that heated water being sucked out of the aircraft at 40 000 feet could easily boil very rapidly into vapour before it had time to cool and freeze. (Yes, yes, I know it is minus 60 up there at times.)
Do we have someone who really know or a science geek who can comment?
Green Guard
15th Oct 2007, 12:58
C'mon mate ! You do not need any science here !
Which aircraft toilet today (unless you and the toilet are in fire, or the aircraft has been produced in Oz) would DELEVER your (after) hand wash water BOILING !!!!!
Green Guard,
Do we have someone who really knows or a science geek who can comment?
Can someone give the potable water volume for their version of the A380?