Vacuum Waste system Vs Recirculating

[AeroTech]

Hi,

Modern aircraft are fitted with vacuum waste system at the opposite of old aircraft that are fitted with recirculating waste system.

a) What are advantages and the disadvantages of vacuum waste system?

b) What are advantages and the disadvantages of recirculating waste system?

c) How often the toilet is used in short/medium aircraft? How full the waste tank after flight?

d) Do you think it is worth to use recirculating waste system in modern short/medium aircraft? If yes/no, why?

Feedback appreciated.

[Fly3]

Where did the recycled waste go?

[TURIN]

When do you need the answers to be submited for your thesis? Google is your friend.


Posted from Pprune.org App for Android

[renard]

The aircraft I fly uses vacuum pumps for the toilets.

If the vacuum pump is unservicable, the toilets will flush as normal if the the aircraft is above 18,000 feet.

Most of the time the aircraft is above 18,000' and when we are below 10,000' the toilets are not in use - seat belt signs are on.

[Piltdown Man]

a) What are advantages and the disadvantages of vacuum waste system?

A vacuum waste system gets rid of the dead otters pretty quick, even the big ones. But two loos often mean flapper valves, computers and other such like. These and vacuum pumps add an extra level of complexity and resultant weakness are causes of unreliability.

b) What are advantages and the disadvantages of recirculating waste system?

They are cheaper but I (and most passengers) don't like seeing bits of mashed up turd and bog paper "flushing" the loo. Also, if I want to smell other people's **** I'll join one of those kinky clubs that politicians and High Court judges belong to.

c) How often the toilet is used in short/medium aircraft? How full the waste tank after flight?

It depends on who the passengers are and the timing of the flight. I've been on one hour flights where nobody had used the loo and others where the traps have been in continuous use. But a one hour flight generally (with say 33 users) only yields about 30-40 litres and I believe our waste tank is 200 litres or so and has one warning light when 75% full and another at 95%.

d) Do you think it is worth to use recirculating waste system in modern short/medium aircraft? If yes/no, why?

NO! See b) above. Plus a vacuum system also gets rid of most of the things bloody women throw down the traps.

PM

[grounded27]

We have vacuum waste systems for several reasons. Less weight and they do not smell as bad. Old blue water systems are horrible. The days of stupid pax dropping junk in them that clogs the systems are done.

The vacuum waste system uses about 5 oz of water per flush if I remember correctly.

Negatives.

As said above, if the jet pumps go out you need to rely on altitude for a vaccum system. One point waste usually dual tanks, I once had a dump valve break both tanks were dependant on this valve, this was a grounding and really shiiy experience.

Blue water, they stink, they jam they need more maintenance and servicing.

I work on freighters, they are all blue water. It is the ideal system for an aircraft that only has crew using them but they still stink!

[EW73]

Well, we had the blue water type on the B747-200s we operated for Air Atlanta from Tunis Airport, doing regular flights to/from southern France, some years ago now!

I was operating the airplane on the initial flights, and when we returned to Tunis I was asked by the ground maintenance crewchief if there was any toilet servicing carts for this airplane type at the airport, since Tunis Air only had A320s and the like.
Why he asked me I don't know, but I didn't know about such things, and answered in the negative!
Minutes later, obviously pissed off, he had released both dump valves and unloaded both full holding tanks on to the tarmac, luckily in an area slightly away from the terminal building, though on brand new concrete tarmac!
I called 'Ground' for help with getting the fire appliances over to wash the stuff away, but they wouldn't help, not a fire! - so it soaked right in - and as you know, new concrete is like a sponge with stains!
As far as I know, there is still two rather large blue stains on their newish tarmac area! :ugh:

[sb_sfo]

The days of stupid pax dropping junk in them that clogs the systems are done.

Don't believe that for one second. Pax are stupid whether vacuum or recirc. One day last week, 2 different airplanes, total of 4 clogged vacuum toilets. I have had better days...

[FlightPathOBN]

Boeing patented the flush system on the aircraft.

They use a vacuum pump, until above 15,000, then it uses the cabin pressure to flush the system.

At flight altitudes of approximately 15,000 feet and higher, the pressure external to the aircraft is low enough that the waste-holding tank 12 is evacuated through the evacuation line 14 by the low ambient air pressure external to the aircraft in comparison with the cabin pressure within the aircraft. For altitudes lower than 15,000 feet and while the aircraft is on the ground, evacuation is provided by a vacuum blower 18 located in line with the evacuation line 14. T


http://operationsbasednavigation.com/wordpress/wp-content/uploads/2013/05/ScreenHunter_47-May.-21-07.34.jpg

edit: Here are the 2 patents, recirc and non-recirc...the patent language gives a very detailed description of the systems and benefits...

Nonrecirculating vacuum flush toilet system utilizing fresh water (http://www.google.com/patents/US4521925)

RECIRCULATING TOILET SYSTEM (http://www.google.com/patents/US3922730)

[ampclamp]

vac systems have more passenger appeal being far less smelly but as far as maintenance goes we seem to have more trouble with vac systems. more complex , just as blockable . cans blankets nappies sanitary stuff.:yuk: