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Troubleshooting & Service Teledyne API - T100 UV Fluorescence SO2 Analyzer
240
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;
faulty lamp transformer; aging or faulty UV detector; dirty optical components; pin holes or
scratches in the UV optical filters; light leaks.
STR LGT
≤ 100 ppb / Zero Air
High stray light could be caused by: aging UV filter; contaminated reaction cell; light leak;
pneumatic leak.
DRK PMT
-50 to +200 mV
High dark PMT reading could be due to: light leak; shutter not closing completely; high
pmt temperature; high electronic offset.
DRK LMP
-50 to +200 mV
High dark UV detector could be caused by: light leak; shutter not closing completely; high
electronic offset.
HVPS
≈ 400 V to 900 V
Incorrect HVPS reading could be caused by; HVPS broken; preamp board circuit
problems.
RCELL TEMP
50ºC ± 1ºC
Incorrect temperature reading could be caused by: malfunctioning heater; relay board
communication (I
2
C bus); relay burnt out
BOX TEMP
Ambient
+ ≈ 5ºC
Incorrect temperature reading could be caused by: Environment out of temperature
operating range; broken thermistor; runaway heater
PMT TEMP
7ºC ± 2ºC Constant
Incorrect temperature reading could be caused by: TEC cooling circuit broken; High
chassis temperature; 12V power supply
IZS TEMP (option)
50ºC ± 1ºC
Malfunctioning heater; relay board communication (I
2
C bus); relay burnt out
PRESS
Ambient
± 2 IN-HG-A
Incorrect sample gas pressure could be due to: pneumatic leak; malfunctioning valve;
malfunctioning pump; clogged flow orifices; sample inlet overpressure; faulty pressure sensor
SLOPE
1.0 ± 0.3
Slope out of range could be due to: poor calibration quality; span gas concentration
incorrect; leaks; UV Lamp output decay.
OFFSET
< 250 mV
High offset could be due to: incorrect span gas concentration/contaminated zero air/leak; low-
level calibration off; light leak; aging UV filter; contaminated reaction cell; pneumatic leak.
TIME OF DAY
Current Time
Incorrect Time could be caused by: Internal clock drifting; move across time zones;
daylight savings time?
06807C DCN6650