Filter
Top Products
249
11.2. 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 11-3 can be used as a basis for taking action
as these values change with tim
e. 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 11-3: Predictive uses for Test Functions
FUNCTION CONDITION BEHAVIOR
INTERPRETATION
STABILITY
Zero Cal Increasing
Pneumatic Leaks – instrument & sample system
Detector deteriorating
CO MEAS
Zero Cal Decreasing
Source Aging
Detector deteriorating
Optics getting dirty or contaminated
Increasing
Source Aging
Detector deteriorating
Contaminated zero gas (H
2
O)
Zero Cal
Decreasing
Source Aging
Detector deteriorating
GFC Wheel Leaking
Pneumatic Leaks
Contaminated zero gas (CO)
Increasing
Source Aging
Pneumatic Leaks – instrument & sample system
Calibration system deteriorating
GFC Wheel Leaking
MR RATIO
Span Cal
Decreasing
Source Aging
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
06864B DCN6314