Brooks Instrument GF81 - Manual (Page 41)

4-3
Brooks ® GF40/GF80/GF81 Devices
Installation and Operation Manual
X-TMF-GF40-GF80-Series-MFC-eng
Part Number: 541B161AAG
June, 2013 Section 4 Maintenance & Troubleshooting
GF40/GF80/GF81 Series
Performance
Possible Causes
Inaccurate flow. Temperature shift (steady state or transient).
Inlet pressure shift (steady state or transient).
Power supply problem.
Electrical interference
Dirty gas chamber
Changes in gas.
Control problems. Can Differential pressure not within operating range
not reach setpoint. Inlet pressure not stable
Oscillation.
Zeroing problems, Indicated Temperature shift (steady state or transient).
zero is not stable. Inlet pressure shift (steady state or transient).
Power supply problem.
Electrical interference
Table 4-1 Environmental Factors
4-4 Troubleshooting Checklist
1. Check environmental factors that could affect changes to GF40/GF80/
GF81 Series performance. The most common environmental factors are
listed in Table 4-1.
2. Check supply voltage and check for a consistent ground.
3. Insure OEM tool setpoint matches the setpoint at the GF40/GF80/GF81
Series. Observe for consistency.
4. Verify isolations valves are open and the gas supply is turned on. Then
verify operating pressures are within operating ranges.
5. Check GF40/GF80/GF81 Series voltage response by moving the
setpoint back and forth.
Observe for voltage changes.