Teledyne 6200T - Sulfides Analyzer - Manual (Page 242)

Troubleshooting Model 6200T Total Sulfur Analyzer
242 Teledyne Analytical Instruments
12.1.2. Fault Diagnosis with Test Functions
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 principles of operation (refer
to Section 13. We recommend use of the AICOM remote control program (Section 7) 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 12-2 contains some of the more common causes for
these values to be out of range.
I MPORTANT I MPACT ON R EADINGS OR D ATA
A value of “XXXX” displayed for any of these TEST functions indicates an
OUT OF RANGE reading.
Note
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.
Table 12-2: Test Functions - Possible Causes for Out-Of-Range Values
TEST FUNCTION NOMINAL VALUE(S) POSSIBLE CAUSE(S)
STABIL ≤1 ppb with Zero Air
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.
SAMPLE FL 650 cm 3 /min ± 10%
Faults are caused due to: clogged critical flow orifice; pneumatic leak; faulty flow sensor;
sample line flow restriction.
PMT
-20 TO 150 mV with
Zero Air
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.
It takes 24-48 hours for the PMT exposed to ambient light levels to adapt to dim light.
NORM PMT
0-5000 mV, 0-20,000 ppb
@ Span Gas Concentration
Noisy Norm PMT value (assuming unchanging SO
2
concentration of sample gas):
Calibration error; HVPS problem; PMT problem.
UV LAMP SIGNAL
2000 - 4000 mV
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.
LAMP RATIO 30 TO 120%
The current output of the UV reference detector divided by the reading stored in the
CPU’s memory from the last time a UV Lamp calibration was performed. Out of range
lamp ratio could be due to: malfunctioning UV lamp; UV lamp position out of alignment;