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PP904A AND B DIFFERENTIAL PRESSURE REGULATORS
Piping
To Flow Measuring Station (FMS)
1. Push the branch and main tubing onto the pigtail
connectors (PP904A) or the restrictor (PP904B). See
Fig. 3.
NOTE: The PP904A connectors are 1/4 in. (6mm) pigtail for
main line and 5/32 in. (4mm) pigtail for branch line.
The PP904B restrictor has 1/4 in. (6mm) connectors.
PIGTAILS (PP904A ONLY)
BRANCH LINE
MAIN LINE
THROTTLING
RANGE
ADJUSTMENT
THROTTLING
RANGE
ADJUSTMENT
LEVEL
NOZZLE
VALVE
ASSEMBLY
(SEE DETAIL "A"
FOR PP904B)
PORT C
DETAIL "A"
Fig. 3. Major component locations of PP904A and B.
2. The PP904 can be connected in two ways for direct act-
ing control which increases branch line pressure (BLP)
and increases airflow:
95-5519EF
PP970A RELAY
SETPOINT ADJUSTMENT
FINE
COARSE
SETPOINT
ADJUSTMENT
LEVER
SETPOINT
LEVEL
FLAPPER
SETPOINT
SCALE
PORT A
POINTER
RESTRICTOR
BRANCH
LINE
MAIN
LINE
NOZZLE
M18385
a. Connect the PP904 port A to the flow measuring
station (FMS) port L. See Fig. 4. This is the low or
static pressure connection.
b. Connect the PP904 port B to the FMS port H. This is
the high or total pressure connection. See Pneu-
matic Airflow Control Modular Engineering Drawings
77-5066.
DIRECT ACTING SHOWN
Fig. 4. Velocity pressure sensing with
flow measuring station.
To Static Pressure Sensing Heads
1. Push the branch and main tubing onto the PP904A pig-
tail connectors or the PP904B restrictor. See Fig. 3.
NOTE: The PP904A connectors are 1/4 in. (6mm) pigtail for
main line and 5/32 in. (4mm) pigtail for branch line.
The PP904B restrictor has 1/4 in. (6mm) connectors.
2. Install the 14004238-001 Duct Static-Pressure Sensing
Head in the duct. See Fig. 5.
3. Connect the tubing from the pressure sensing head to
the PP904 port C for direct-acting or port A for reverse-
acting control. See Fig. 6.
4.
Connect PP904 branch line to the control device and
the main line to main air.
HEAD
NO. 8 SHEET
METAL SCREWS
Fig. 5. Duct static pressure sensing head installation.
2
FMS
AIR FLOW
L
H
C
A
M18384
M18383
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