Chapter Eight: Troubleshooting Troubleshooting Chart
74
MFC clogged sensor Run MFC diagnostics. Verify MFC
inlet pressure, check valve current
for open valve condition and check
for gas flow downstream of MFC. If
flow present, possible clogged
sensor
MFC control circuit failure Run MFC diagnostics. If error
results, contact MKS service center.
MFC shows output flow >
FS (overrange)
MFC valve full open Check valve current for maximum
condition
Pressure drop across MFC is
greater than specification
Measure upstream pressure &
downstream pressure. Compare to
specification.
Faulty valve control
circuit/calibration
Run MFC diagnostics using Ethernet
GUI
Possible contamination in valve
assembly
Cycle-purge MFC to clear suspected
contamination
MFC output signal does
not match setpoint
Contamination Check for partial block orifice or
sensor. Cycle purge MFC to clear
contaminant
Inlet pressure too low Increase inlet pressure
Outlet pressure too high Decrease outlet pressure
Flow signal is not properly
grounded.
Check for ground loops.
Control electronics failure,
sensor failure
Run MFC diagnostics test
MFC output signal
oscillates
Inlet pressure oscillates Check for faulty regulator
Inlet pressure too high Lower inlet pressure
Inlet pressure too high Adjust programmed inlet pressure
through Ethernet GUI.
MFC nameplate gas not same
as actual gas
Check for programmed gas using
Ethernet GUI or digital interface.
Reprogram as necessary
Faulty control circuit Run MFC diagnostic test.
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