Brooks Instrument GF81 - Manual (Page 44)

4-6
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
Symptoms & Possible Causes Corrective Action
5. No gas flow below some setpoint.
NOTE: When the setpoint is
decreased below this point, the
GF40/GF80/GF81 Series signal remains at
some value higher than the
setpoint.
Is the gas inlet/outlet differential Verify that the pressure is correct for
pressure too high? regulator to achieve proper pressure.
Is the GF40/GF80/GF81 Series leaking? Check for contamination. Test the GF40/GF80/GF81 Series
for leak integrity. Replace the GF40/GF80/GF81 Series
if leakage is detected.
6. Gas flow oscillates.
Is the GF40/GF80/GF81 Series calibrated for the Check the GF40/GF80/GF81 Series side can label. Run
gas flowing? a flow check to verify. If flow is incorrect,
replace the
GF40/GF80/GF81 Series.
Is there too much gas pressure Verify that the pressure is correct for
across the GF40/GF80/GF81 Series? this gas and range. If required, adjust
regulator to achieve proper pressure
reading.
Are inlet and outlet pressures stable? If outlet pressure is unstable, check for
(no oscillation or hunting) a faulty vacuum pump,
or hunting at a downstream valve.
Check inlet pressure on tool. A faulty
pressure regulator can make the
GF40/GF80/GF81 Series appear to oscillate.
Adjust inlet pressure up or down by 2
psig increments until hunting disappears.
Verify common gas pressure is
within range.
NOTE: Hunting or oscillation can be
contributed to multiple
GF40/GF80/GF81 Series sharing
a common gas manifold. Therefore,
inspect gas delivery sources to
the gas box (for example; two tools
sharing a common gas bottle and
calling for gas at the same time). Valve leak.
Unregulated gas pressure from Facilities.
Table 4-2 GF40/GF80/GF81 Series Troubleshooting Guide (Continued)