2-9
Brooks
®
Digital MFC's & MFM's
Section 2 Installation
Installation and Operation Manual
X-TMF-SLA5800-MFC-eng
Part Number: 541B027AAG
April, 2013
2-11 Operation Check Procedure (Analog I/O)
a. Mount the MFC/MFM in its final orientation.
b. Apply power to the MFC/MFM and allow approximately 45 minutes for
the instrument to completely warm up and stabilize its temperature.
c. Do NOT supply gas to the MFC/MFM. Ensure that the differential
pressure across the MFC/MFM is zero.
d. Apply a setpoint of:
0.000 Vdc ± 10 mV (0 - 5 Vdc setpoint)
1.000 Vdc ± 10 mV (1 - 5 Vdc setpoint)
0.000 mA ± 100 μA (0 - 20 mA setpoint)
4.000 mA ± 100 μA (4 - 20 mA setpoint)
e. If the zero exceeds one of these limits, follow the re-zeroing procedure
in Section 3-4. The analog output signal should be:
0.000 Vdc ± 10 mV (0 - 5 Vdc output)
1.000 Vdc ± 10 mV (1 - 5 Vdc output)
0.000 mA ± 40 μA (0 - 20 mA output)
4.000 mA ± 40 μA (4 - 20 mA output)
f. Turn on the gas supply. A positive flow signal may be present due to
slight valve leak-thru (MFC only).
g. Supply a setpoint signal between:
0 to 5 Vdc (0 - 5 Vdc setpoint)
1 to 5 Vdc (1 - 5 Vdc setpoint)
0 to 20 mA (0 - 20 mA setpoint)
4 to 20 mA (4 - 20 mA setpoint)
h. Check the analog output signal. The output signal should match the
setpoint signal in accordance with the accuracy specifications provided
in Section 1-4 of this document.
i. If flow output signal does not match the setpoint, and pressure settings
are correct, this could indicate a problem in the MFC. A secondary
issue could be the gas type. When checking with a surrogate gas,
ensure that there is enough pressure to the MFC in order to flow the
correct amount of the surrogate gas.
Example:
Checking an MFC calibrated for 100 ccm SF6 (sulfur hexafluoride).
The sensor factor N
2
(nitrogen) is 0.27, therefore the eqivalent N
2
needed is 100/0.27 = 370.4 ccm. This may require a pressure
increase to make this flow rate.
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