C
A
AIR
FLO
W
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
PP970A RELAY
MAIN LINE
THROTTLING
SETPOINT ADJUSTMENT
RANGE
FINE
ADJUSTMENT
COARSE
SETPOINT
THROTTLING
ADJUSTMENT
RANGE
LEVER
ADJUSTMENT
SETPOINT
LEVEL
LEVEL
NOZZLE
VALVE
FLAPPER
ASSEMBLY
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.
FMS
AIR FLOW
L
H
C
A
DIRECT ACTING SHOWN
M18384
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
(SEE DETAIL "A"
SETPOINT
Head in the duct. See Fig. 5.
SCALE
3.
Connect the tubing from the pressure sensing head to
FOR PP904B)
PORT C
PORT A
POINTER
4.
the PP904 port C for direct-acting or port A for reverse-
acting control. See Fig. 6.
Connect PP904 branch line to the control device and
the main line to main air.
DETAIL "A"
RESTRICTOR
BRANCH
LINE
MAIN
LINE
HEAD
NOZZLE
M18385
NO. 8 SHEET
Fig. 3. Major component locations of PP904A and B.
METAL SCREWS
M18383
2.
The PP904 can be connected in two ways for direct act-
ing control which increases branch line pressure (BLP)
Fig. 5. Duct static pressure sensing head installation.
and increases airflow:
95-5519EF
2
