Fault Diagnosis With Test Functions - Teledyne T100 Instruction Manual

Troubleshooting & Repair

10.1.2. FAULT DIAGNOSIS WITH TEST FUNCTIONS

IMPORTANT
Note
Table 10-2: Test Functions - Possible Causes for Out-Of-Range Values
TEST
NOMINAL VALUE(S)
FUNCTION
≤1 ppb with Zero Air
STABIL
SAMPLE FL 650 cm
-20 TO 150 mV with Zero
PMT
0-5000 mV, 0-20,000 ppb
NORM PMT
UV LAMP
SIGNAL
2000 - 4000 mV
264
Besides being useful as predictive diagnostic tools, the TEST functions, viewable from
the front panel, can be used to isolate and identify many operational problems when
combined with a thorough understanding of the analyzer's theory of operation (refer to
Section 9). We recommend use of the APICOM remote control program to download,
graph and archive TEST data for analysis, and long-term monitoring of diagnostic data.
The acceptable ranges for these test functions are listed in Table A-3 in Appendix A-3.
The actual values for these test functions on checkout at the factory were also listed in the
Final Test and Validation Data Sheet, which was shipped with the instrument. Values
outside the acceptable ranges indicate a failure of one or more of the analyzer's
subsystems. Functions with values that are within the acceptable range but have
significantly changed from the measurements recorded on the factory data sheet may also
indicate a failure or a maintenance item.
A problem report worksheet has been provided in Appendix C to assist in recording the
value of these test functions. Table 10-2 contains some of the more common causes for
these values to be out of range.
A value of "XXXX" displayed for any of these TEST functions indicates an OUT OF
RANGE reading.
Sample Pressure measurements are represented in terms of absolute pressure because
this is the least ambiguous method reporting gas pressure.
Absolute atmospheric pressure is about 29.92 in-Hg-A at sea level. It decreases about 1
in-Hg per 1000 ft gain in altitude. A variety of factors such as air conditioning systems,
passing storms, and air temperature, can also cause changes in the absolute
atmospheric pressure.
Faults that cause high stability values are: pneumatic leak; low or very unstable UV lamp
output; light leak; faulty HVPS; defective preamp board; aging detectors; PMT recently
exposed to room light; dirty/contaminated reaction cell.
Faults are caused due to: clogged critical flow orifice; pneumatic leak; faulty flow sensor;
3
/min ± 10%
sample line flow restriction.
High or noisy readings could be due to: calibration error; pneumatic leak; excessive
background light; aging UV filter; low UV lamp output; PMT recently exposed to room
light; light leak in reaction cell; reaction cell contaminated HVPS problem.
Air
It takes 24-48 hours for the PMT exposed to ambient light levels to adapt to dim light.
Noisy Norm PMT value (assuming unchanging SO
Calibration error; HVPS problem; PMT problem.
@ Span Gas
Concentration
This is the instantaneous reading of the UV lamp intensity. Low UV lamp intensity could
be due to: aging UV lamp; UV lamp position out of alignment; faulty lamp transformer;
aging or faulty UV detector; UV detector needs adjusting; dirty optical components.
Intensity lower than 600 mV will cause UV LAMP WARNING. Most likely cause is a UV
lamp in need of replacement.
Teledyne ML - T100 UV Fluorescence SO2 Analyzer
POSSIBLE CAUSE(S)
06807A(DCNxxxx)
concentration of sample gas):
2