Aalborg AFC - Manual (Page 22)

the transducer. The unit will now act as a mass flow meter.
CAUTION: If the valve is left in the AUTO (control) or OPEN mode for an
extended period of time, it may become warm or even hot to the touch.
Use care in avoiding direct contact with the valve during operation.
Follow steps outlined in section 7.2 and 7.3, then continue with step 7.4.2 below.
7.4.2 Valve Adjustment
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
AFC just stops.
7.4.3 Full Scale Flow Adjustment
Fully open the flow regulator upstream of the AFC. Increase the inlet pressure to
20 psig (25 psig for AFC 46). Apply a +5.00 VDC set point reference. Using the
calibrator check the flow rate. If necessary, adjust R21 to match the desired full
scale flow rate. [In control mode, turning R21 clockwise will decrease the flow.
Conversely, turning R21 counterclockwise will increase the flow through the AFC.]
7.4.4 25% Flow Adjustment
Change the set point 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 [R21], until the flow output is
correct.
7.4.5 50% Flow Adjustment
Change the set point to 2.50 VDC to control at 50% 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 [R45], until the flow output is correct.
7.4.6 75% Flow Adjustment
Change the set point to 3.75 VDC to control at 75% 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 [R44], until the flow output is correct.
7.4.7 100% Flow Adjustment
Change the set point to 5.00 VDC to control at 100% 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 [R43], until the flow output is correct.
Repeat steps 7.4.4 to 7.4.7 at least once more.
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