Brooks Instrument Mfi Series - Manual (Page 32)

3-4
Brooks ® Mf Series
Section 3 Operation
Installation and Operation Manual
X-TMF-Mfi-Mfx-MFC-eng
Part Number: 541B074AAG
August, 2009
3-4 Calibration Procedure
Note 1: If the valve has been disassembled and any of the following parts
have been replaced, the control valve adjustment procedure in Section 4-
4c must be performed before the Mf Series instrument is calibrated.
orifice
valve stem
plunger
lower guide spring
valve seat
Note 2: Calibration of the Mf Series Controller/Meter requires the use of a
digital voltmeter (DVM) and a precision flow standard calibrator. It is
recommended that the calibration be performed only by trained and
qualified service personnel.
Note 3: If the mass flow controller/meter is to be used on a gas other than
the calibration gas, apply the appropriate sensor conversion factor. For
controllers size the orifice for actual operating conditions, refer to
Section 4-6.
a. With the controller installed in an unpressurized gas line, apply power
and allow approximately 45 minutes for warm-up. During the warm-up,
adjustment and calibration check procedures, do not allow the control
valve to open when gas flow is not present. This situation is not a
normal operating mode; it will cause the control valve to abnormally
heat up. A controller with an abnormally warm valve will be difficult to
calibrate. This situation can be prevented by the valve override "closed"
when there is no gas flow, or setting the setpoint to less than 1%. Also
avoid unnecessary periods with the valve override "open".
b. Adjust the anticipate potentiometer fully clockwise (twenty turns). Then
adjust the anticipate potentiometer ten turns counterclockwise to center
the potentiometer. This will provide a rough adjustment of this circuit
and make the flow more stable for calibration.
c. Connect the DVM positive lead to the 0-5 V signal output TB-1,
Terminal 5, and the negative lead to signal common (Terminal 4).
Adjust the zero potentiometer for an output of 0 mV ±2mV (refer to
Figures 3-4 and 3-5 for test point and potentiometer locations).
d. Apply pressure to the system and insure that the zero signal repeats
within 2 mV of the voltage set in Step c above, If the zero does not
repeat, check for leakage.
e. Adjust the setpoint for 100% flow (5.000 V or 20.00 mAdc). Connect the
DVM positive lead to TP2 (linearity voltage) and the negative lead to
TP4 (circuit common). Adjust the linearity potentiometer for an output of
0.00 V (zero Volts).