Section 2 Installation
Operation Check Procedure: Digital 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. Turn on the gas supply. A positive flow signal may be present due to
slight valve leak-thru (MFC only).
d. Provide the proper UOM setpoint between 20% and 100% FS to the
MFC via the digital network controller.
e. Check the MFC Flow value. It should match the setpoint UOM. Value
within ± 0.2% FS in less than 10 seconds after setpoint change.
f. If flow output signal does not match the setpoint, and pressure set
-
tings are correct, this could indicate a problem in the MFC. A second-
ary 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 N2 (nitrogen) is 0.27, therefore the equivalent N2
needed is 100/0.27 = 370.4 ccm. This may require a pressure increase
to make this flow rate.
Digital Configuration
NOTE: This information and all other detailed communication information is
available in the appropriate communication supplement instruction manual.
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