11.17 - Water and Waste Flashcards
Where are the potable water tanks normally installed?
Potable water is stored in one or more tanks below the cabin floor.
How is potable water pumped to the taps?
Air pressure is taken from the pneumatic or the air conditioning system.
Check valves may also hold this pressure while on the ground.
Also, air compressor pumps which automatically start when the system pressure drops below a minimum may also be fitted on some aircraft.
How are the potable water tabks pressurised for maintenance?
A pressure port in the form of a Shrader valve is pressurised with nitrogen.
How is the tap water heated and to what temperature?
Water is passed through an in-line electrical heater which is installed in each toilet.
Water is heated to 45^C
When filling a potable water tank, how do you know how much water is in it?
There is a water quantity indicator on the potable water servicing panel.
What are the two ways to dispose of waste water?
- Overboard System
- Internal tank system
How is air prevented from leaking out of a sink drain in flight in an overboard system?
Under each sink, a float valve is provided to prevent a leakage of the cabin air pressure through the drain valves.
What fluid is used in a self contained toilet system?
The solution is blue coloured and odorising additives are mixed in it. It’s called Racasan
How is a self-contained toilet system flushed?
The waste water tank is initially filled with the minimum amount of flush fluid (chemical-water solution).
A pump is installed in each tank, which uses the chemical-water solution to flush the bowl.
In a vacuum toilet system where does the vacuum come from?
Differential pressure between the cabin and the outside atmosphere. On modern commercial aircraft there are no engine driven negative differential pumps.
They use an aneroid switch in the tail section for the delta p.
(On ground and below 16000 ft, high speed blowers generate required pressure differential.)
Where is the water sourced in a vacuum toilet system?
The drain lines allow flushing the tanks after draining them and to pre-charge the tanks with a small amount of chemical water solution (Normally 13L per tank).
Clear Potable water is used for flushing the bowl
Explain the way potable water is routed to the water taps?
The pipes are routed through the fuselage which includes some cold sections, in these zones, the plumbing must be insulated or heated, normally it is done electrically.
It is routed below cabin floor and as taps are above, air pressure is used from the pneumatic system, the air conditioning system, check valves to hold pressure on ground and even sometimes air compressor pumps which automatically turn on if pressure drops below a certain point.
Why is it necessary to drain the water system during longer cold parking periods?
Water may freeze and damage the system components and leak after that.
What are the two ways to dispose of waste water?
- The overboard system which drains water overboard through heated drainmasts. The drainmasts are heated to prevent the waste water freezing.
- The internal tank system which uses waste water to flush toilet bowls before being sucked into the toilet waste water tank.
Potable water is stored in one or more tanks ____________
Below the cabin floor
Cold water is directly routed to the taps, but hot water passes through an in-line _____ _____ _____ installed in ___ ____
The water is heated to approx _____
electrical water heater
each toilet
45^C
Self contained toilets are initially _______
filled with minimum amount of flush liquid (chemical-water solution).
A pressure differential moves the ____ from the toilet bowls to the ____ ____ in a vacuum toilet system
waste
waste tanks
In a vacuum waste system,
On the ground and below 16 000 ft (4850m) altitude, ___________ generate the required pressure differential
High Speed Blowers
In a vacuum toilet system,
The drain lines allow flushing the tanks after draining them and to _______ the tanks with a small amount of chemical-water solution (normally 13L per tank)
The service panel is ______ to prevent from freezing
pre-charge
heated
