6. TROUBLESHOOTING
Page 123 © 1998 DH Instruments, Inc.
SYMPTOM POSSIBLE CAUSE SOLUTION
Poor pressure control. Unstable or incorrect pressure supply.
Connect regulated pressure supply set
to correct supply pressure (2.3.3).
Won't AutoZero at vacuum, ERROR:
data rejected.
Vacuum supply is not low enough; Lo
reference transducer isolation valve
leaks or reference transducer needs to
be recalibrated.
Assure that vacuum supply is correct,
check reference transducer calibration
coefficients (5.2, 2.3.4, 5.4).
Poor pressure control and
measurement.
The PPC2 AF and/or the connection
to the test system is contaminated
with liquids.
Purge and clean affected systems
(3.2.8, 5.1.3).
Apparent inaccurate pressure
control/measure and little or no
response from reference transducer:
Reference transducer destroyed by
overpressure.
Isolate failure and have repaired as
needed.
Apparent inaccurate pressure
measurement/control and "H" is
displayed on top line of screen.
An unplanned "head" correction is
active or head height or gas is
incorrect.
Remove or change "head" correction
(3.2.7).
Incorrect pressure units and/or
measurement mode (gauge or absolute).
Set desired pressure units and/or
measurement mode. Consider reference
temperature if unit is inWa (3.2.2).
Apparent inaccurate pressure
measurement/control.
Reference transducer calibration
coefficients have been altered.
Check and correct calibration
coefficients if needed (5.4).
System is vented but does not
indicate zero because measurement
mode is absolute.
Check measurement mode setting
and current value of atmospheric
pressure if absolute (3.2.2).
VENT port is plugged. Open VENT port to atmosphere.
Will not vent.
Vent valve not operating. Have unit serviced.
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