DOC AIRBUS | AMM A320FAIR SUPPLY BOOST SYSTEM - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The air supply boost-system gives pressure to the potable water system if no bleed air pressure is available. It makes sure that the potable water system works at the correct pressure.
** ON A/C NOT FOR ALL The air supply boost-system gives pressure to the potable water system if no bleed air pressure is available. It makes sure that the potable water system works at the correct pressure.
2. Component Location
** ON A/C NOT FOR ALL 
Air-Supply Boost System - Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 8MD | COMPRESSOR | 162DW | 171 | 38-42-00 | |
| 10MD | SWITCH,PRESSURE | 161DW | 171 | 38-42-16 | |
| 3000MM | TANK-POTABLE WATER | 161DW | 171 | 38-11-41 | |
| 4205MM | VALVE-CHECK | 161DW | 171 | 38-41-41 | |
| 4206MM | VALVE,NON RETURN | 171 | 25-10-00 | ||
| 4210MM | FILTER-AIR | 161DW | 171 | 38-41-42 | |
| 4212MM | FILTER,AIR | 171 | 25-10-00 | ||
| 4215MM | SHUTTLE VALVE-AIR | 171 | 38-41-44 | ||
| 4200MM | VALVE-PRESSURE REDUCING | 161DW | 171 | 38-41-43 | |
3. System Description
The air supply boost-system supplies compressed air to potable water tank 3000MM. The system operates independently from the bleed air system of the aircraft and the ground-air pressure supply.
The normal pressure of the potable water system is between 25 psi (1.7237 bar) and 28 psi (1.9305 bar).
The system has:
** ON A/C NOT FOR ALL The air supply boost-system supplies compressed air to potable water tank 3000MM. The system operates independently from the bleed air system of the aircraft and the ground-air pressure supply.
The normal pressure of the potable water system is between 25 psi (1.7237 bar) and 28 psi (1.9305 bar).
The system has:
- Compressor 8MD
- Pressure switch 10MD
- Air filter 4212MM
- Check valve 4206MM.
4. Power Supply
The electric motor that drives the compressor is supplied with 115VAC at 400HZ from 3-phase AC BUS 2. This is switched to the motor through relay 9MD, that is powered from 28VDC GND/FLIGHT BUS.
** ON A/C NOT FOR ALL The electric motor that drives the compressor is supplied with 115VAC at 400HZ from 3-phase AC BUS 2. This is switched to the motor through relay 9MD, that is powered from 28VDC GND/FLIGHT BUS.
5. Interface
Limit switch 5MA at service panel 171AL is connected between 28VDC GND/FLIGHT BUS and pressure switch 10MD. When service panel 171AL is open, relay 9MD is de-energized and stops the electric motor of compressor 8MD. A bayonet-type electrical connector connects 115VAC supply to compressor 8MD.
** ON A/C NOT FOR ALL Limit switch 5MA at service panel 171AL is connected between 28VDC GND/FLIGHT BUS and pressure switch 10MD. When service panel 171AL is open, relay 9MD is de-energized and stops the electric motor of compressor 8MD. A bayonet-type electrical connector connects 115VAC supply to compressor 8MD.
6. Component Description
(1) The compressor is a reciprocating piston type which is electrically driven.
The compressor supplies 3801.6 in.3 (62297.20 cm3) per minute of clean compressed air at 30 psi (2.0684 bar) to the water tank.
The compressor can work continuously to give this pressure and volume of air.
The compressor has:
The compressor supplies 3801.6 in.3 (62297.20 cm3) per minute of clean compressed air at 30 psi (2.0684 bar) to the water tank.
The compressor can work continuously to give this pressure and volume of air.
The compressor has:
- an electric motor,
- a housing,
- a crankshaft,
- bearings,
- inlet and outlet valves,
- an inlet filter,
- a piston rod,
- a piston cup,
- a relief valve.
(2) The electric motor is fan cooled and has its own housing. The motor operates at 12000 rpm. A thermal-overload protection circuit stops the motor if it becomes too hot. The thermal-overload protection circuit starts the motor again when the temperature of the motor decreases to the normal temperature.
(3) A driven pulley is connected to a crank shaft which connects to and moves a piston and piston cup in the cylinder. The piston cup is filled with teflon material and is self-lubricating. This is necessary to keep the compressed air output clean.
B. The Pressure Switch 10MD.
Pressure switch 10MD senses the pressure in the potable water tank and sets the electric motor (of the compressor) on and off. At 27.5 psi (1.8961 bar), the pressure switch disconnects the 28VDC line from the relay. This stops the electric motor. When the pressure in the potable water tank is 25.5 psi (1.7582 bar), the pressure switch connects the 28VDC line. This causes the relay to start the electric motor of the compressor to pressurize the system.
Pressure switch 10MD senses the pressure in the potable water tank and sets the electric motor (of the compressor) on and off. At 27.5 psi (1.8961 bar), the pressure switch disconnects the 28VDC line from the relay. This stops the electric motor. When the pressure in the potable water tank is 25.5 psi (1.7582 bar), the pressure switch connects the 28VDC line. This causes the relay to start the electric motor of the compressor to pressurize the system.
C. The Relay 9MD.
Relay 9MD is installed below the aircraft floor at FR 65. It is a 28VDC operated switch that connects and disconnects 115VAC BUS 2 to the electric motor. 28VDC electrical power that operates the relay, is supplied from the GND/FLIGHT BUS. This is supplied through limit switch 5MA of the maintenance door and pressure switch 10MD.
Relay 9MD is installed below the aircraft floor at FR 65. It is a 28VDC operated switch that connects and disconnects 115VAC BUS 2 to the electric motor. 28VDC electrical power that operates the relay, is supplied from the GND/FLIGHT BUS. This is supplied through limit switch 5MA of the maintenance door and pressure switch 10MD.
D. Air Filter(s)
(1) Air filter 4212MM:
The air filter stops the ingress of impurities into the system from the air around the compressor.
The air filter stops the ingress of impurities into the system from the air around the compressor.
E. Check valve 4206MM:
The check valve makes sure that the compressed air flows only in the direction of the potable water tank.
The check valve makes sure that the compressed air flows only in the direction of the potable water tank.
7. Operation
The usual cycle of the compressor increases the pressure in the potable water tank to 28 psi (1.9305 bar). At this pressure, pressure micro switch 10MD stops the power supply to relay 9MD.
If the air pressure in the potable water system decreases less than 25.5 psi (1.7582 bar):
The usual cycle of the compressor increases the pressure in the potable water tank to 28 psi (1.9305 bar). At this pressure, pressure micro switch 10MD stops the power supply to relay 9MD.
If the air pressure in the potable water system decreases less than 25.5 psi (1.7582 bar):
- Pressure micro switch 10MD energizes relay 9MD.
- The compressor starts and the pressure in the potable water system increases for one more cycle.
- Pressure micro switch 10MD de-energizes relay 9MD.
- The compressor stops.