Pressure Reducing Valve Figure 009
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F. Check Valve (1382GM, 1388GM, 2388GM and 3388GM)
(Ref. Fig. 010)
All the check valves installed in the reservoir pressurization system are the same. They are of the flapper type.
G. Air Pressure Gage
An air pressure gage is installed in the air supply line to each reservoir. The gage gets input of the system pressure which is constantly displayed. The gage has an analog display with a range of 0-75 psi.
H. Reservoir Pressurization Ground Connector
(Ref. Fig. 011)
The ground connector is installed on the reservoir pressurization unit. The connector is a plunger-type valve. It is opened and closed manually. Rotation of the nut moves the plunger in or out to open or close the valve. A cap fitted to the connector prevents external contamination.
J. Restrictor Valve (1392GM)
(Ref. Fig. 011)
A restrictor valve is installed in the HP air supply line from the left engine. It has a calibrated orifice which restricts the volume of air which can flow through it. It also has a filter element to prevent contamination of the valve.
5. Operation
_________
**ON A/C 001-049, 051-099, 101-149, 201-299,
(Ref. Fig. 005)
R **ON A/C 151-199, 301-399, 401-499,
(Ref. Fig. 005A)
**ON A/C ALL
(Ref. Fig. 008)
Check Valve Figure 010
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Reservoir Pressurization Ground Connector and Restrictor Valve
Figure 011
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R In flight, two sources of air supply are available to the reservoir
R pressurization unit (HP air from the left engine and LP air from both
R engines and the APU). The air supply from the left engine goes through the
R restrictor (1392GM) (located in the pylon) and then into the unit (1360GM)
R through the check valve. On the ground the air supply by means of a ground
R supply cart goes directly into the unit. In the unit the HP air supply, or
R ground air supply goes through the filter and the water separator and the
R pressure reducing valve to the check valve. The LP air supply from the bleed
R air system goes directly into the unit via the LP relief valve through the
R filter and the water separator and the pressure reducing valve to the check
R valve. The air supply of the higher pressure will close the check valve in
R the other supply line.
R
R From the unit the air supply divides into three flows (one to each
R reservoir). Each air supply goes through its applicable check valve (1388GM,
R 2388GM or 3388GM) and to its related reservoir (1000GQ, 2000GQ and 3000GQ).
R It also goes to its:
R - air pressure gage (1383GM, 2383GM and 3383GM),
R - low pressure switch (1384GM, 2384GM and 3384GM),
R - pressure relief valve (1005GM, 2005GM and 3005GM),
R - reservoir depressurization valve (1087GM, 2087GM and 3087GM).
R
R You can depressurize each reservoir independently through the applicable
R reservoir depressurization valve. To open the valve, turn the cap assembly
R thru 90 degrees. This allows the air pressure through the valve assembly to
R the atmosphere. Alternatively, you can remove the cap assembly and connect a
R ground depressurization coupling.
A malfunction of the reservoir pressurization unit caused by freezing is
prevented without bleed air warming flow.
The water separator of the reservoir pressurization unit has in addition to
a manual draining device an automatic draining function. The low pressure
circuit of the reservoir pressurization system activates the automatic
draining function as follows:
- After each engine or APU shutdown a spring loaded plunger releases a hole
on the backside of the unit. Any collected water drains out of the hole.
- When the APU or the engines start again, the pressure in the low pressure
circuit of the reservoir pressurization system moves the plunger back to
its initial position. The hole on the backside of the unit is now closed
and a green indicator is visible on the water separator, to show that the
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