Aalborg GFC - Manual (Page 23)

7.2.9 75% Flow Adjustment
Using the flow regulator, increase the flow rate to 75% of full scale flow. Check the
flow rate indicated against the flow calibrator. The output of the flow meter should
read 3.75VDC ±63mV (or 16mA ±0.25mA). If the reading is outside of that range,
place the jumper at [J1B] as appropriate to increase or decrease the signal. Adjust
the setting for potentiometer [R39] by using the insulated screwdriver through the
access window, until reading is within specification.
7.2.10 100% Flow Adjustment
Using the flow regulator, increase the flow rate to 100% of full scale flow. Check
the flow rate indicated against the flow calibrator. The output of the flow meter
should read 5.00VDC ±63mV (or 20mA ±0.25mA). If the reading is outside of that
range, place the jumper at [J1C] as appropriate to increase or decrease the sig-
nal. Adjust the setting for potentiometer [R40] by using the insulated screwdriver
through the access window, until reading is within specification.
Repeat steps 7.2.7 to 7.2.10 at least once more.
7.2.11. VALVE ADJUSTMENT
7.2.11.1 Valve Adjustment for GFC 17/37/47
Discontinue the PURGE mode (set valve for the closed position). Apply an inlet
pressure of 5 psig, and atmospheric pressure at the outlet. If a small flow occurs,
turn the set screw on top of the solenoid valve clockwise until the flow through the
GFC just stops
7.2.11.2 Valve Adjustment for GFC 57/67/77
DO NOT adjust the motorized valve for GFC57/67/77.
The motorized valve for these models has been pre-adjusted at the factory.
7.2.12 Full Scale Flow Adjustment
Fully open the flow regulator upstream of the GFC. Increase the inlet pressure to
20 psig (25 psig for GFC47). Apply a +5.00 VDC (100% full scale flow) setpoint
reference. Using the calibrator check the flow rate. If necessary, adjust R33 to
match the desired full scale flow rate. [In control mode, turning R33 clockwise will
decrease the flow. Conversely, turning R33 counterclockwise will increase the flow
through the GFC.]
7.2.13 25% Flow Adjustment
Change the setpoint to 1.25 VDC to control at 25% of full scale flow. Check the
flow rate indicated against the flow calibrator. If the flow rate is not within ±0.75%
of full scale, re-adjust the setting for potentiometer [R33], until the flow output is
correct.
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