Brooks Instrument Mfi Series - Manual (Page 30)

3-2
Brooks ® Mf Series
Section 3 Operation
Installation and Operation Manual
X-TMF-Mfi-Mfx-MFC-eng
Part Number: 541B074AAG
August, 2009
• Precision 5 Volt Reference allows the direct connection of a setpoint
potentiometer to produce a 0-5 Volt command signal to the controller. A
precision ten-turn 2 K ohm potentiometer with an integral turns counter
is recommended. This will permit repeatable adjustments of setpoint to
1 part in 1,000.
• Valve Override allows full opening and closing of the control valve
independent of the command setting. Refer to Section 2-6.
3-2 Operating Procedure
a. Apply power and allow approximately 45 minutes for the instrument to
warm-up and stabilize its temperature.
b. Turn on the gas supply.
c. Command 0% flow to the controller/shut-off flow to the meter and
observe the instrument's output signal. If the output is not zero mVdc
±.05 mAdc, check for leaks and if none are found, refer to the re-
zeroing procedure in Section 3-3.
d. Set the command for the desired flow rate to assume normal controller
operation. Open valve to allow flow to pass through the meter. Monitor
the flow signal output.
Figure 3-1 Flow Sensor Operational Diagram