47
Section 4 Maintenance & Troubleshooting
Symptoms & Possible Causes
Corrective Action
6. Gas flow, or GF100 Series pressure reading
oscillates.
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.
NOTE: Most GF100 Series calibrated
with nitrogen will oscillate
Check inlet pressure on tool. A faulty
with hydrogen or helium.
pressure regulator can make the
GF100 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 GF100 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.
7. GF100 Series does not read zero pressure
when gas is shut off.
Is the differential pressure across
Verify that the pressure is correct for
the GF100 Series really zero?
the gas and range. If the GF100 Series has
been contaminated, it may not be able
to close, and therefore, will not zero.
Equalize the pressure across the GF100 Series by
opening it briefly. Set up the GF100 Series for zeroing.
Then perform the zeroing procedure in Section 2-14.
Is the GF100 Series configured properly
Use the tool software to verify.
in the tool software?
Is the GF100 Series mounted to the
Refer to the side can label on the GF100 Series.
proper attitude?
The GF100 Series should be calibrated
in the attitude it will be operating at.
8. OEM tool does not read correct GF100 Series
zero reading.
Is the differential pressure across the
GF100 Series valve leakage.
GF100 Series really zero?
Incorrect MFC zero.
Is the supply voltage within specified range?
Is the GF100 Series mounted in the proper attitude?
Is the flow output signal of the GF100 Series
really zero?
9. Zero Drift.
Improper zero of the GF100 Series?
GF100 Series aging or sensor stabilization.
Excessive Valve leakage?
Zero is not correct.
Table 4-2 GF100 Series Troubleshooting Guide (Continued)
