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Model GFC7000E Instruction Manual MAINTENANCE SCHEDULE & PROCEDURES
04584 Rev A1 148
9.2. Predicting Failures Using the Test Functions
The Test Functions can be used to predict failures by looking at how their values change over
time. Initially it may be useful to compare the state of these Test Functions to the values recorded
on the printed record of the final calibration performed on your instrument at the factory, p/n
04307. Table 9-3 can be used as a basis for taking action as these values change with time. The
internal data acquisition system (iDAS) is a convenient way to record and track these changes.
Use APIcom to download and review this data from a remote location.
Table 9-3: Predictive uses for Test Functions
Function Condition Behavior Interpretation
Stability Zero Cal Increasing
Pneumatic Leaks – instrument & sample
system
Detector deteriorating
CO2 MEAS Zero Cal Decreasing
Source Aging
Detector deteriorating
Optics getting dirty or contaminated
Increasing
Source Aging
Detector deteriorating
Contaminated zero gas (H2O)
Zero Cal
Decreasing
Source Aging
Detector deteriorating
GFC Wheel Leaking
Pneumatic Leaks
Contaminated zero gas (CO
2
)
Increasing
Source Aging
Pneumatic Leaks – instrument & sample
system
Calibration system deteriorating
MR Ratio
Span Cal
Decreasing
Source Aging
GFC Wheel Leaking
Calibration system deteriorating
Increasing > 1”
Pneumatic Leak between sample inlet
and Sample Cell
Change in sampling manifold
Pres Sample
Decreasing > 1”
Dirty particulate filter
Pneumatic obstruction between sample
inlet and Sample Cell
Obstruction in sampling manifold
PHT Drive
Any, but with
Bench Temp
at 48°C
Increasing
Mechanical Connection between IR-
Detector and Sample Cell deteriorating
IR-Photodetector deteriorating
Increasing
See MR Ratio - Zero Cal Decreasing
above
Offset Zero Cal
Decreasing See MR Ratio - Zero Cal Increasing
above
Increasing
See MR Ratio - Span Cal Decreasing
above
Slope Span Cal
Decreasing
See MR Ratio – Span Cal Increasing
above
9.3. Maintenance Procedures
The following procedures are to be performed periodically as part of the standard maintenance of
the Model GFC7000E.