11. TROUBLESHOOTING
Many pr
oblems that appear to be MFC-related may actually be caused by another part of the
system. Go through the step-by-step Troubleshooting Guide (Appendice 16.3) before removing the
MFC from service.
Environmental factors may affect MFC performance (see Table 1) but these are easily resolved
using a simple troubleshooting checklist (see Table 2).
11.1 Environmental Factors
Table 1. Environmental factors
11.2 MFC Troubleshooting Checklist
Check For These Factors:
- Verify that the supply voltage is correct.
- Verify that the grounding is consistent.
- Verify that the setpoint signal at the MFC connector is the same as the setpoint signal
coming from the tool.
- V
erify that the Output (Indicated Flow) of the fl
ow controller is the same at the input of the
tool.
- Verify the valve voltage response.
- Move the setpoint upward and downward, looking for the valve voltage to change
accordingly.
- Compare recent valve voltage to past valve voltage. If it has changed and the other
parameters have not then a failur
e is likely
.
11
SYMPTOMS CAUSES
Inaccurate flow (span shifts)
•
Temperature (steady state and transient)
•
Inlet pressure (steady state and transient)
•
Power supply problems, electrical interference
Control problems
•
Differential pressure not within operating range
(cannot reach setpoint, oscillation)
•
Inlet pressure not stable
•
Cable losses (too much ground current
Zero problems
•
Temperature (steady state and transient)
(indicated zero not stable)
•
Inlet pressure (steady state and transient)
•
Power supply problems, electrical interference
•
Attitude sensitivity
©2005 Celerity
, Inc.
#199-001-0006 REV
.F 4/05
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
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