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Teledyne API Model 200A NO
X
Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
Table 9-1: Test Functions (Continued)
Test Function Factory Set-Up Comment
OZONE FL 60 - 90 This is the Ozone flow. It is measured by a solid state flow meter,
and thus is a true indication of flow.
If you suspect there is no ozone being generated, disconnect the
tube at the reaction cell and rub the end of the tube on your
fingertips, then sniff your fingers. The odor of ozone should be
readily apparent.
PMT 0-5000 mV
This is the instantaneous output of the PMT. During normal
operation the value varies widely as the M200A switches from NO
to NO
x
to AutoZero modes. Changes in reading will be
synchronized with valve switching. The PMT voltage values will
be relatively constant when:
1. Electric test - variation in the 2000 mV signal observed will be
sampling errors of the V/F board and preamp noise. See Section
9.1.3.2.
2. Optic test - variation in the 2000 m
V signal will be PMT dark
current
, preamp, HVPS plus item 1 above. See Section 9.1.3.3.
3. Sampl
ing zero gas - signal from 1, 2 plus signal from ozone
generator air
4. Sampling pure NO span gas - signal will be 1, 2, 3, above plus
signal from chemiluminescent reaction. Slight pulsations will
be noticed as the M200A switches from NO to NO
x
. This is due
to differences in flowrates in each channel. These differences
are taken out in the calibration process resulting in slightly
different slopes for the NO and NO
x
channels. Large pulsations
when switching to the NO
x
channel is indicative of a bad moly
converter.
When sampling zero gas the PMT reading should be less than
150 mV and relatively constant.
High or noisy readings could be due to:
1. Excessive background light which is caused by a possible
contaminated reaction cell.
2. Humidity (undried ambient air) in the ozone generator feed air.
3. PMT recently exposed to room light. It takes 24-48 hours for
the PMT to adapt to dim light.
4. Light leak in reaction cell.
5. 5Improper slopes.
NORM PMT 0-5000 mV The Normalized PMT reading is to be used as the PMT reading
during the FACTORY CALIBRATION procedure. In addition to
the raw mV reading from the PMT this reading is adjusted using
certain other factors to produce an accurate reading for the Factory
Calibration procedure.
(table continued)
9-5
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