Riser-Line Shut-off Valve
 Figure 005
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 CES 

 Main-Distribution-Line Shut-Off Valve
 Figure 006
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 If there is a small leak through the oxygen regulators 910WR1 or 910WR2 the bleed/vent valve 7503WR releases the unwanted oxygen. It prevents an unwanted build up of pressure in the supply lines. When the emergency oxygen system operates, the unwanted air in the supply lines is bled through the bleed/vent valve 7503WR. This is to make sure that the supply lines only contain oxygen when the system operates. There are three test ports, which are installed:
 -
in the intermediate line.

 -
in the oxygen distribution system downstream of the oxygen regulators.

 -
in the oxygen distribution system downstream of the check valves. You can increase and descrease the pressure in the system for maintenance works with the test ports.

 4. Component Description
_____________________
 A. Supply Lines
 (Ref. Fig. 007)
 The supply lines in the low-pressure supply system are made of aluminum
 alloy. Flexible hoses connect the emergency oxygen containers to the
 supply lines.

 B. Check Valve 7501WR1 and 7501WR2
 (Ref. Fig. 002) The check valve 7501WR1 is installed in the underfloor supply line between FR26 and FR27. The check valve 7501WR2 is installed in the ceiling supply line between FR26 and FR27. The check valve opens when the emergency oxygen system is pressurized and the oxygen flows in one direction (rear to front). The check valve closes if the oxygen flows in the opposite direction. This occurs if the applicable supply line to the check valve is damaged. The main-distribution-line shut-off valves and the check valves prevent the supply of oxygen to a damaged supply line.
 C. Riser-Line Shut-Off Valves 7514WR1 thru 7514WR4
 (Ref. Fig. 005)
 The riser-line shut-off valves are installed in the engine burst area:

 -
On the riser lines at FR30, FR36

 -
On the fall lines at FR47. They are installed immediately after the connection with the main supply line. The riser-line shut-off valves are pneumatically controlled so that oxygen is not supplied to a damaged riser line. In normal operation the riser-line shut-off valves are open. They close if the flow rate increases to a value more than max. 110 l.min (29.0586 USgal.mn).

 Oxygen Supply Lines
 Figure 007
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 CES 

 A valve stays closed until the pressure difference across the valve is less than 1.0 bar (14.5037 psi).
 D. Test Ports 7504WR1 thru 7504WR3
 (Ref. Fig. 004) The test port 7504WR1 is installed in the intermediate line before the oxygen regulators. It lets you do different tests and checks of the oxygen system. The test port 7504WR2 is installed in the oxygen distribution system downstream of the oxygen regulators. It lets you do different tests and checks of the oxygen distribution system. The test port 7504WR3 is installed in the oxygen distribution system downstream of the check valves. It lets you decrease the pressure of the supply lines downstream of the check valves. If it is necessary to decrease the pressure of the distribution system, you must:
 -
Use the test port 7504WR2 for the rear part of the distribution system.

 -
Use the test port 7504WR3 for the forward part of the distribution system.

 NOTE : The inlet of the test port has the same functions and dimensions
____ as the test port used on Airbus Single-Aisle Crew Oxygen-System (Puritan-Bennett Aero Systems Co., Part Number 110111).
 E. Emergency Oxygen Containers
 (Ref. Fig. 008, 009)
 (1)
 The emergency oxygen containers are self-contained units. Two types of containers are installed:

 -
Type I: is installed in the overhead stowage PSU channels with two to four masks

 -
Type II: is installed in the sidewall panels, ceiling panels and lavatories with two masks.

 (2)
 The components of the emergency oxygen containers are:

 (a)
 The oxygen mask container, type I or II.

 (b)
 A door-stop assembly to let you do an inspection or make a test of the emergency oxygen container without release of the oxygen masks. You can pull out the door-stop with your fingers. When the door-stop is in the extended position the word TEST and the number of masks in the container is shown on the door stop.
　
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