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Teledyne API Model 200AU NO
X
Analyzer Instruction Manual, 02293, Rev. F
9-5
Table 9-1: Test Functions (Continued)
Test Function Factory Set-Up Comment
OZONE FL
80 cc/min
±
10
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 M200AU switches from
NO to NO
x
to Pre-reactor 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 mV signal will be PMT dark
current, preamp, HVPS plus item 1 above. See Section 9.1.3.3.
3. Sampling 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 M200AU 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. Improper 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)