Teledyne GFC-7000T - Trace CO2 Analyzer - manual - Manual (Page 201)

Maintenance Model GFC7000TA Carbon Dioxide Analyzer
Teledyne Analytical Instruments 183
8.2. 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 (DAS) is a convenient way to record and track these changes. Use APICOM to download and
review this data from a remote location.
Table 8-3: 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
MR RATIO
Zero Cal
Increasing
Source Aging
Detector deteriorating
Contaminated zero gas (H2O)
Decreasing
Source Aging
Detector deteriorating
GFC Wheel Leaking
Pneumatic Leaks
Contaminated zero gas (CO
2
)
Span Cal
Increasing
Source Aging
Pneumatic Leaks – instrument & sample system
Calibration system deteriorating
Decreasing
Source Aging
GFC Wheel Leaking
Calibration system deteriorating
PRES
Sample
Increasing > 1”
Pneumatic Leak between sample inlet and Sample Cell
Change in sampling manifold
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
OFFSET Zero Cal
Increasing See MR Ratio - Zero Cal Decreasing above
Decreasing See MR Ratio - Zero Cal Increasing above
SLOPE Span Cal
Increasing See MR Ratio - Span Cal Decreasing above
Decreasing See MR Ratio – Span Cal Increasing above