aislepathlight
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Aircraft Toilets

Fri Aug 25, 2006 11:33 am

I have many a times standing in the lavs, wondering how airplane toilets work. Recently I have noticed that you have air coming in through the vents in the door, meaning to me, that there is some vacuum or low pressure part, but don't fully understand. I have decided to turn to you, a.netters, and need your help on understanding aircraft lavs.

So how do they work?
bleepbloop
 
WNCrew
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RE: Aircraft Toilets

Fri Aug 25, 2006 12:53 pm

It was explained to me that the modern airliner toilets flush by opening a valve to the outside which allows the pressure from inside the cabin to force the waste down into a holding tank. SO, really it's just by utilizing the already present positive cabin pressure.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
2H4
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RE: Aircraft Toilets

Fri Aug 25, 2006 3:27 pm



I had a WN maintenance guy explain how the system works, but I don't remember the details. I do, however, remember him describing how some engineers at Boeing flushed an object of some kind in the forward lav, and clocked the time it took for it to reach the aft holding tank.

They then converted the time and distance into miles per hour, and although I forget the figure, I remember the maintenance tech wrapping the presentation up by professing "That's one fast turd".




Quoting AirWillie6475 (Reply 4):
The guy above has some serious errors.

Relax. It's not your duty to call attention to them, or call him out on them. Just ignore it and get on with life.  Smile




2H4


Intentionally Left Blank
 
AirWillie6475
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RE: Aircraft Toilets

Fri Aug 25, 2006 3:42 pm

Quoting 2H4 (Reply 6):
It's not your duty to call attention to them, or call him out on them. Just ignore it and get on with life

I'm doing him a favor, if he wrote like that on something serious like a resume the employer will just pass right to the next person.
 
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HAWK21M
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RE: Aircraft Toilets

Fri Aug 25, 2006 5:57 pm

Waste of Thread space on Teaching English....Folks......Lets concentrate on the Topic.



Normally there are Two Types.The Recycling type & the Vaccum type.

The Former has the Water treated with DDD [Dye,DisInfectant,Deodrant] in a Tank below the Commode.A reversible motor is used to port the Water around the commode when the Flush is operated.The Waste & water drains back in the Tank.

The Vaccum type uses Vaccumm compressor or Ambient air depending on the Altitude to create a low pressure after a bit of Water is sprinkled on the commode.The waste is collected in a Tank [On B737 located in the Aft Cargo Compt].

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
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RE: Aircraft Toilets

Fri Aug 25, 2006 5:58 pm

I have met three types of aircraft toilets.
Type 1.
B737-2/3/4/5, DC9 B757 type where you sit on a tank of fluid. When you operate the flush this liquid which usually starts out blue but turns brown after a while! is circulated by a pump. The whole unit is self contained and drained via an external connection, one at a time.
Type 2
Tristar type which has a tank at the front, and another at the rear. Each tank serves up to five toilets but otherwise works the same as type 1.
Some tristars have type 1 toilets as well at L2 R2 doors.
Type 3.
Vacuum toilets. The tank is at the back of the aft freight. It is kept at a pressure below the cabin in flight by being open to the outside. When you operate the flush a tiny amount of fresh water is squirted intio the bowl and then the whole lot is sucked back into the tank. Below 10000ft their is a pair of vacuum pumps which run when you operate the flush lever to suck the fluids aft.
Ventilation.
the air you hear going past the door is ventilation. All toilets have a vent fan which sucks air out of the toilet and sends it overboard. There is typically a pair of vent fans at the back near the outflow valve. On our B757 the intake to these fans is down in the bowl so you sometimes hear the little flaps banging away when their springs are getting old.
 
2enginesonly
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RE: Aircraft Toilets

Fri Aug 25, 2006 7:08 pm

There's another one Steve.
The old funnel and hose as used in our Coastguard Cessna 404......aim, shoot and score !!!!  Smile

Arjan
 
airfoilsguy
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RE: Aircraft Toilets

Fri Aug 25, 2006 7:30 pm

Can you dump the tank in flight. Perhaps over oceans.
It's not a near miss it's a near hit!!
 
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Starlionblue
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RE: Aircraft Toilets

Fri Aug 25, 2006 8:46 pm

Quoting Airfoilsguy (Reply 14):
Can you dump the tank in flight. Perhaps over oceans.

Nyet. But I'm pretty sure that's what they did back in the day.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
flymatt2bermud
Posts: 551
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RE: Aircraft Toilets

Fri Aug 25, 2006 9:06 pm

Quoting 2H4 (Reply 9):
please talk about aircraft toilets now?

Here's a fun scenario! What happens when one of the heated waste tubes collapses. Two days ago we were into the 6th hour of a 9 hour flight and one of the waste tubes collapsed. The position of the failure conveniently knocked out all available vacuum flush toilets. I guess I have to purchase a camper toilet to carry around in the future in the event this occurs again. The toilets are readily available...does anyone know where to purchase those super heavy duty bags? Yikes.

Quoting Airfoilsguy (Reply 14):
Can you dump the tank in flight. Perhaps over oceans.

Offshore rules on waste dumping don't apply to aircraft (maybe aircraft carriers). Dumping does occur unintentionally when the blue water leaks out and freezes into a mass then drops off when the temperatures increase on descent. Just ask the people who live West of O'Hare.

Checklist:
[x] spellcheck
[ ] grammar check ???
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
 
Tristarsteve
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RE: Aircraft Toilets

Fri Aug 25, 2006 9:07 pm

Quoting Airfoilsguy (Reply 14):
Can you dump the tank in flight. Perhaps over oceans

No, but on vacuum systems there is a level sensor that shuts down the system when the tank is full. There is an override button for this sensor. You can then typically operate the flush one more time, and if the tank is full then the waste comes out the breather!!. Seen it happen on the ground.

But the totally separate grey water drains from the toilet and galley sinks go straight out overboard via heated drain masts.
 
N231YE
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RE: Aircraft Toilets

Fri Aug 25, 2006 10:45 pm

Quoting 2H4 (Reply 6):
I do, however, remember him describing how some engineers at Boeing flushed an object of some kind in the forward lav, and clocked the time it took for it to reach the aft holding tank.

They then converted the time and distance into miles per hour, and although I forget the figure, I remember the maintenance tech wrapping the presentation up by professing "That's one fast turd".

If I remember correctly, didn't BA unravel a whole roll of toilet paper from a toilet/lavatory near the back of a 747 all the way up to the front, and then flush it. I believe the paper was downed in a few seconds.
 
Tod
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RE: Aircraft Toilets

Fri Aug 25, 2006 10:50 pm

Quoting FlyMatt2Bermud (Reply 16):
What happens when one of the heated waste tubes collapses

Waste tubes are not heated  yuck 

As far as my personal experence, I've never seen a collapsed waste tube.
(could happen, I guess, but...)

The waste tubes used in a typical vacuum system are 2 inch diameter titanium or stainless steel with a wall thickiness between .020 and .035 inch.

Quoting AislepathLight (Thread starter):
Recently I have noticed that you have air coming in through the vents in the door,

In most cases, there should always be some air entering the lav from the cabin. There are usually two air lines attached to a lav. One providing positive air flow into the lav from either the conditioned air system or the gasper system. The other air line is connected to the lav/galley vent system and this extracts the sticky air and sends it to the outflow valve area.

The lav/galley vent airflow leaving the lav should always be more the the cond air or gasper air coming in. In addition to keeping much stinky air from entering the cabin, this is to pass the FAA smoke penetration testing requirements. This test involves putting smoke into the lav and assuring that none leaks into the cabin. To further complicate things, the air being extracted from the lav should not be alot more the air being introduced or when you put smoke into the lav to test the smoke detection system, it can be extracted too quickly and you fail that required test.

Other airflow within the lav can come from the sink drain, when this is open the pressure differential between the cabin and the outdoors cause air to flow out of the lav to the drain mast via the grey water drain system.

Old blue juice style lavs will also have the holding tank under the throne connected to the lav/galley vent system to assist with stinky removal.

Tod
 
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HAWK21M
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RE: Aircraft Toilets

Fri Aug 25, 2006 10:50 pm

Quoting 2enginesonly (Reply 13):
The old funnel and hose as used in our Coastguard Cessna 404......aim, shoot and score

Thats one Important Toilet  Smile

Quoting Airfoilsguy (Reply 14):
Can you dump the tank in flight. Perhaps over oceans.

Not on todays Aircraft.

Quoting Bri2k1 (Reply 18):
Any Link

You are the smarty according to most,you tell us mere mortals  Smile

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tod
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RE: Aircraft Toilets

Fri Aug 25, 2006 10:56 pm

Quoting 2H4 (Reply 6):
engineers at Boeing flushed an object

Canned dog food and IIRC it's over a hundred miles an hour.

Tod
 
flymatt2bermud
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RE: Aircraft Toilets

Fri Aug 25, 2006 11:50 pm

Quoting Tod (Reply 20):
Waste tubes are not heated

In fact on this model aircraft the fantastic newly designed vacuum system has a waste tube that is made of a synthetic material and the tube is heated. The manufacturer says the heat is the culprit that has compromised the rigidity of the tube allowing it to collapse under pressure. They have recently had a rash of these instances and when I contacted $hit support on the SAT phone at 30W they told me there was nothing I could do inflight and we were #3 to report the failure in three weeks. There is a bulletin that replaces the original tube but disconnects the heating element until a permanent fix can be approved.

No frills flights are one thing but no lav....unacceptable.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
 
2H4
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RE: Aircraft Toilets

Fri Aug 25, 2006 11:54 pm




Quoting Tod (Reply 22):
IIRC it's over a hundred miles an hour.

Yeah, that sounds about right. For some reason, I'm thinking it was 104 mph, but I'm not certain.

Quoting FlyMatt2Bermud (Reply 16):
The toilets are readily available...does anyone know where to purchase those super heavy duty bags? Yikes.

RV and camper supply stores come to mind...I think one is called "Camping World"...but you might also check Cabela's or Gander Mountain...




2H4


Intentionally Left Blank
 
Tod
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RE: Aircraft Toilets

Sat Aug 26, 2006 1:19 am

Quoting FlyMatt2Bermud (Reply 23):
In fact on this model aircraft the fantastic newly designed vacuum system has a waste tube that is made of a synthetic material and the tube is heated.

Thanks for the correction. thumbsup 

What model of aircraft?

Unless the tubes were right up against the skin, why would a waste tube be heated? Even the 744 upper deck waste tubes that run right down the frame, nearly touching the stringers for over 100 inches are not heated.

Tod scratchchin 
 
flymatt2bermud
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RE: Aircraft Toilets

Sat Aug 26, 2006 3:59 am

Quoting Tod (Reply 26):
In fact on this model aircraft the fantastic newly designed vacuum system has a waste tube that is made of a synthetic material and the tube is heated.

Thanks for the correction.

What model of aircraft?

BD700 Global Express XRS & 5000
The Global Express 5000 and XRS models came out in 3RD QTR 05 with many new and updated systems. The airline style vacuum toilets were introduced and I have no idea who would have thought a non-metal tube would be satisfactory in such a high pressure system.

Quoting Tod (Reply 26):
Unless the tubes were right up against the skin, why would a waste tube be heated? Even the 744 upper deck waste tubes that run right down the frame, nearly touching the stringers for over 100 inches are not heated.

Good question and I can only theorize as an operator. The Global Express aircraft operate up to FL510 and (depending upon the stage length) regularly above FL450. Perhaps they were concerned that the colder temps at those altitudes may have created a potential freezing issue.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
 
Skyslave
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RE: Aircraft Toilets

Sat Aug 26, 2006 5:12 am

All these toilets sound too complex. Why not just have a suction tube that fastens to your anus, and fires your fecal matter out into the wild blue yonder? I mean, with all the advancements in laser targeting, we could surely get that turd within a 1 block radius of a pond or lake... or something. Am I right?

edit: Oh, and have it make that delightful *KAPOOT* sound after it exits the aircraft.

[Edited 2006-08-25 22:23:09]
 
2H4
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RE: Aircraft Toilets

Sat Aug 26, 2006 5:25 am




Quoting Skyslave (Reply 28):

I'd say it would be more efficient to harness the methane and use it to power the APU.




2H4


Intentionally Left Blank
 
flymatt2bermud
Posts: 551
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RE: Aircraft Toilets

Sat Aug 26, 2006 5:31 am

Quoting 2H4 (Reply 29):
harness the methane and use it to power the APU

Then that would properly identify where the P U in APU came from in the first place.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward" Leonardo Da Vinci
 
doug_or
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RE: Aircraft Toilets

Sat Aug 26, 2006 6:17 am

On the subject of airborne lav science. A 737-900 can suck up a legnth of toilet paper extending to the cockpit door from the rear lav in a single flush.
When in doubt, one B pump off
 
FlyingColours
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RE: Aircraft Toilets

Sat Aug 26, 2006 8:32 am

Ahhhh TP Racing  Smile I've heard so much about it and yet not been blessed with the chance to do it myself. On the first/last flights of the season when our 767s are flying empty 1 crewmember will take 1 loo roll and place it in the aft right lav and unroll it all the way forward and another crewmember will do the same on the opposite, they then see which one is the quickest.

Still there is also the olde "Tug of war", on the later 757 with the airflow system, take a loo roll and place one end in the mid left loo, and the other end in the lav on the opposite side of the isle, have a crewmember in each press at the same time and see which one got the most roll.

Anyway I've not done that, but I have a few questions and points.

Quoting TristarSteve (Reply 12):
Type 1.
B737-2/3/4/5, DC9 B757 type where you sit on a tank of fluid. When you operate the flush this liquid which usually starts out blue but turns brown after a while! is circulated by a pump. The whole unit is self contained and drained via an external connection, one at a time.

I never knew that it was recycled, I guess it does explain a lot though.

Is it possible to have 5 LAVs on a 757-200, 2FWD and 3MID/AFT? I mean with a Type 1 I think it is but with the type 3 system.

Also, on most of our 75s we have type 1 lavs installed, and have 1fwd and 3 by doors 3, 2 on the left and 1 on the right. Are those 3 mid ones sharing a single tank?

Phil
FlyingColours
Lifes a train racing towards you, now you can either run away or grab a chair & a beer and watch it come - Phil
 
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Starlionblue
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RE: Aircraft Toilets

Sat Aug 26, 2006 9:50 am

Quoting Doug_Or (Reply 31):
On the subject of airborne lav science. A 737-900 can suck up a legnth of toilet paper extending to the cockpit door from the rear lav in a single flush.

Sounds like a fun experiment. Next time, bring a camcorder and share the fun! Big grin
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
bohica
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RE: Aircraft Toilets

Sat Aug 26, 2006 12:30 pm

How about this. In the lav stick a bit of toilet paper in the lav while still on the roll. Flush the toilet and see how fast the roll spins while its being unwound. Not only that, there is no toilet paper left for the poor sap who uses the lav next.  Big grin
 
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HAWK21M
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RE: Aircraft Toilets

Sat Aug 26, 2006 4:12 pm

Quoting Doug_Or (Reply 31):
A 737-900 can suck up a legnth of toilet paper extending to the cockpit door from the rear lav in a single flush.

Heard this was done Practically too  Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
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RE: Aircraft Toilets

Sat Aug 26, 2006 4:17 pm

Quoting FlyingColours (Reply 32):
Also, on most of our 75s we have type 1 lavs installed, and have 1fwd and 3 by doors 3, 2 on the left and 1 on the right. Are those 3 mid ones sharing a single tank?

No individual tanks. If you see the servicing panel door open which is on the centreline under the belly, then look for one yellow drain handle for each tank.
 
Tristarsteve
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RE: Aircraft Toilets

Sat Aug 26, 2006 4:21 pm

The British Airways 10 old A320 from 1988 are fitted with individual type 1 toilets. So the fwd toilet has a servicing panel under and just fwd of L1 door. A pig for the honey truck guys to reach as the jetty is in the way.
Are there any other A320 with non-vacuum toilets?
I see that our A319 from 2002 have this servicing panel fitted but blanked off. If Airbus still make the cutout for the panel, I suppose it is an option you can specify.
 
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HAWK21M
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RE: Aircraft Toilets

Sat Aug 26, 2006 4:23 pm

Quoting TristarSteve (Reply 36):
No individual tanks. If you see the servicing panel door open which is on the centreline under the belly, then look for one yellow drain handle for each tank.

On our Freighters there is just ONE Lavatory,Servicing is more longer Interval scheduled  Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
FlyingColours
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RE: Aircraft Toilets

Sat Aug 26, 2006 7:57 pm

Quoting TristarSteve (Reply 36):
No individual tanks. If you see the servicing panel door open which is on the centreline under the belly, then look for one yellow drain handle for each tank

Thanks Steve, I'll take a look the next time I'm down there  Smile

Phil
FlyingColours
Lifes a train racing towards you, now you can either run away or grab a chair & a beer and watch it come - Phil
 
curlyheadboy
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RE: Aircraft Toilets

Sat Aug 26, 2006 10:06 pm

Quoting AislepathLight (Reply 25):
I have read the story on here about the exploding toilet, and was wondering about what caused the dry ice to go crazy. I would guess that the blue stuff has something nasty in it, and would cause it. Is that guess right?

It used to be formaldehyde, but nowadays they use compounds that are less irritating and toxic from inhalation, such as glutaraldehyde and quaternary ammonium compounds, which I think is the one that started the chemical reaction with the dry ice (carbon dioxide) that the guy stuffed into the toilet...  

And for my grammar... sorry guys, I do what I can, unsing (edit: using ooops!)what I know...  

[Edited 2006-08-26 15:07:51]
If God had wanted men to fly he would have given them more money...
 
EMBQA
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RE: Aircraft Toilets

Sun Aug 27, 2006 1:19 am

Quoting AislepathLight (Thread starter):
So how do they work?

There are two basic types. Recycling and Vaccum.

Recycling is found on smaller regional aircraft. E145, CRJ, Saab, ATR, Dash8..etc. It's just a holding tank the recycles the fluid until flushed and reserviced. It is a one piece unit. There is a screen that seperates the solids and let me tell you it sucks when that get clogged and you need to pull the pump and clean it.... or some dumb passenger throws a diper into teh tank.

Vaccum systems are found on larger aircraft and work almost the same way, but the fluids and solids are held in a seperate holding tank. It works just like your home, but uses a vaccum instead of water pressure to clear the bowl. Most holding tanks seperate out the solids and re-use the 'blue water'
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
Bobster2
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RE: Aircraft Toilets

Sun Aug 27, 2006 1:50 am

Quoting CURLYHEADBOY (Reply 40):
the chemical reaction with the dry ice (carbon dioxide)

CO2 solid + heat --> CO2 gas

Very simple. Water in the toilet provides the heat. Gas takes up much bigger volume than sold. Expanding gas forces water to shoot out of toilet. No chemical reaction.
"I tell you this, no eternal reward will forgive us now for wasting the dawn." Jim Morrison
 
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Starlionblue
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RE: Aircraft Toilets

Sun Aug 27, 2006 5:32 am

Quoting TristarSteve (Reply 37):
The British Airways 10 old A320 from 1988 are fitted with individual type 1 toilets. So the fwd toilet has a servicing panel under and just fwd of L1 door. A pig for the honey truck guys to reach as the jetty is in the way.
Are there any other A320 with non-vacuum toilets?

As I recall, the "old BA 320s" were taken over from British Caledonian. In contrast with the newer 320s at BA, they were the rare -100 version. Perhaps the -200 has vacuum as standard?

Quoting EMBQA (Reply 41):
or some dumb passenger throws a diper into teh tank.

This amazes me. It's not like you can throw a diaper in your toilet at home! Well, not more than a couple of times  Wink
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
curlyheadboy
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RE: Aircraft Toilets

Sun Aug 27, 2006 8:02 am

Quoting Bobster2 (Reply 42):
CO2 solid + heat --> CO2 gas

Very simple. Water in the toilet provides the heat. Gas takes up much bigger volume than sold. Expanding gas forces water to shoot out of toilet. No chemical reaction.

True, I stand corrected.
If God had wanted men to fly he would have given them more money...
 
320tech
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RE: Aircraft Toilets

Sun Aug 27, 2006 1:01 pm

Quoting HAWK21M (Reply 11):
Waste of Thread space

Any Link
regds
BRI


Waste of Thread Space
The primary function of the design engineer is to make things difficult for the manufacturer and impossible for the AME.
 
Tristarsteve
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RE: Aircraft Toilets

Sun Aug 27, 2006 5:48 pm

Quoting Starlionblue (Reply 43):
As I recall, the "old BA 320s" were taken over from British Caledonian. In contrast with the newer 320s at BA, they were the rare -100 version. Perhaps the -200 has vacuum as standard

All A320 have vacuum as standard. But in 1987 vacuum toilets were a new idea and not very reliable so BCAL went for the option of recycling toilets. In hindsight it was a bad move, but at the time it seemed right. The problem with the A320 recycling toilets is that the pulley that the dump cable goes over just under the pan is too small, about 1in dia, compared with a B737 pulley which is about 2in dia, and the cable is always breaking over this pulley and you need to open the dump valve manually. Done it hundreds of times.
 
777wt
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RE: Aircraft Toilets

Mon Aug 28, 2006 1:03 am

Quoting TristarSteve (Reply 16):
But the totally separate grey water drains from the toilet and galley sinks go straight out overboard via heated drain masts.

Thanks for reminding me that morning I worked on 2 nose wheel R&R on a ERJ-170.

I had my toolbox on the r/h side by the nose. While I took the ac out of service for 30 mins, someone in the fwd FA galley or lav decided to use the sink and water came out onto the top of my toolbox. I discovered that after I was putting the tools away after the R&R of the NLG wheels.

I've been told in training that the FA were warned not to pour coffee in the foward sink because in flight they get sucked into the ram air intake which leads to the packs and coffee smell comes in the cabin along with a mess all over the precoolers.
 
777wt
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RE: Aircraft Toilets

Mon Aug 28, 2006 1:08 am

Someone tell em what a "rocket motor" does in the lav system?

I watched mythbusters and they were doing tests on an tiolet system to see if it's possible to get stuck in the tiolet due to a pressure differental in the system. I didn't get to see what it looked like but it was described that it looks like a chopping wheel or a turbocharger wheel inside.
 
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HAWK21M
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RE: Aircraft Toilets

Mon Aug 28, 2006 1:36 am

Quoting 777WT (Reply 46):
I've been told in training that the FA were warned not to pour coffee in the foward sink because in flight they get sucked into the ram air intake which leads to the packs and coffee smell comes in the cabin along with a mess all over the precoolers.

Ram Air & Pack Air are seperate,Very Unlikely that Coffee smell would arise from there.A mess on the Heat Exchangers could be a possibility leading to Pack trips.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
lincoln
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RE: Aircraft Toilets

Mon Aug 28, 2006 10:50 am

Quoting 777WT (Reply 46):
've been told in training that the FA were warned not to pour coffee in the foward sink

I'm not sure if it's related, but on the ex-Presidential 707 at the Musuem of Flight in Washington there's (still) a note in one of the galleys from the maintenance group to the flight attendants, essentially saying "Please help us keep this aircraft looking as nice as it does by not dumping coffee down the sink"

If only I could remember the exact wording...
CO Is My Airline of Choice || Baggage Claim is an airline's last chance to disappoint a customer || Next flts in profile
 
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HAWK21M
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RE: Aircraft Toilets

Mon Aug 28, 2006 4:59 pm

Quoting 777WT (Reply 46):
I had my toolbox on the r/h side by the nose. While I took the ac out of service for 30 mins, someone in the fwd FA galley or lav decided to use the sink and water came out onto the top of my toolbox. I discovered that after I was putting the tools away after the R&R of the NLG wheels.

Some older B737s had the Fwd Toilet sink drain greywater drain into the Commode tank instead of an overboard drain.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
FlyingColours
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RE: Aircraft Toilets

Mon Aug 28, 2006 8:37 pm

Quoting 777WT (Reply 46):
I've been told in training that the FA were warned not to pour coffee in the foward sink because in flight they get sucked into the ram air intake which leads to the packs and coffee smell comes in the cabin along with a mess all over the precoolers.

We are told not to pour Milk, Cofee, Tea, Juice etc down the galley sinks because it clogs the pipes, instead we have to pour them down the toilet.

But I suppose if the galley drains go overboard then perhaps they just don't want tea & cofee stains streaking along the white aircraft  Smile

Phil
FlyingColours
Lifes a train racing towards you, now you can either run away or grab a chair & a beer and watch it come - Phil
 
Tristarsteve
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RE: Aircraft Toilets

Mon Aug 28, 2006 9:46 pm

Quoting FlyingColours (Reply 51):
We are told not to pour Milk, Cofee, Tea, Juice etc down the galley sinks because it clogs the pipes, instead we have to pour them down the toilet.

But I suppose if the galley drains go overboard then perhaps they just don't want tea & cofee stains streaking along the white aircraft

No it is definitely to stop clogging. Most galley sinks have filters and these get blocked with coffee grounds and wine and milk. They are essential because the pipework going down to the drain mast is very small diameter and easily gets blocked, especially when it goes round a 90deg bend. We spend ages cleaning filters and unblocking sinks, so the best advice to cabin crew is try and only pour water down the galley sink, pour everything else down the toilet (and that is the toilet bowl, not the toilet sink!)
 
OlegShv
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RE: Aircraft Toilets

Tue Aug 29, 2006 12:08 am

I've seen a documentary on building the A380 recently. They showed the tests for their toilet system. It's of vacuum type, and it only takes a couple seconds for the "product" from the front lavs to reach the holding tanks in the rear of the plane. So, it travels really fast down those pipes. Fun stuff!
 
Tod
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RE: Aircraft Toilets

Tue Aug 29, 2006 12:12 am

Quoting FlyingColours (Reply 51):
But I suppose if the galley drains go overboard then perhaps they just don't want tea & cofee stains streaking along the white aircraft

JL gave Boeing a lot of grief over this when the received their first 744.
Due the flat fuselage shape, the forward (STA 860) drain mast discharge tends to get sucked up against the fuselage, leaving stains and fouling the center MLG. Different length drain mast were tested, but even with a 30 inch mast the problem was unsolved. Instead it was solve via a placard that discouraged FA from dumping yucky stuff down the drain, especially during final approach.

Quoting TristarSteve (Reply 52):
because the pipework going down to the drain mast is very small diameter and easily gets blocked,

1.00 inch is typical, .75 happens too and .50 is used on many floor and chiller drains.

The other clogging problem come from aircraft such as some 747 that have portions of their grey water drain system heated to prevent freezing. Pour milk and wine together through a heated tube and you get something similar to cottage cheese.

Quoting TristarSteve (Reply 52):
especially when it goes round a 90deg bend.

[RANT MODE = ON]
Bad design practice.
Sometimes it is unavoidable due to structural constrains (Ref: DC9 forward drains), but other times its JUST lazy/dumb design engineers not taking proper precautions.
[RANT MODE = OFF]

Quoting HAWK21M (Reply 50):
Some older B737s had the Fwd Toilet sink drain greywater drain into the Commode tank instead of an overboard drain

This is present on some BBJ too. It allows the operator to use the sink while on the ground.

Tod
 
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HAWK21M
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RE: Aircraft Toilets

Tue Aug 29, 2006 3:07 am

Quoting Tod (Reply 54):
This is present on some BBJ too. It allows the operator to use the sink while on the ground

The risk is capacity.same can overflow if not monitored.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
CRJ900
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RE: Aircraft Toilets

Tue Aug 29, 2006 6:00 am

On the CRJ700/900, does the blue-juice lavs have a common collecting tank below the rear cabin or is all the waste stored under each lav bowl as it has a boxy shape?
Come, fly the prevailing winds with me
 
bri2k1
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RE: Aircraft Toilets

Tue Aug 29, 2006 10:18 am

Quoting Tod (Reply 54):
1.00 inch is typical, .75 happens too and .50 is used on many floor and chiller drains.

Are these numerous drains open to the atmosphere all the time? If so, I can see why they would need to be small, as they would place an additional load on the pressurization system. I know about flow volumes and outflow valves and all, but add up the area of 4-5 1" drains and 4-5 0.5" drains, and you have a significant hole in the pressure vessel.
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