Teledyne T200 Operation Manual page 303

Teledyne API – T200 NO/NO
13.2.4.3. SAMPLE GAS FLOW CALCULATION
13.2.4.4. O SUPPLY AIR FLOW SENSOR
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06858E DCN7057
/NO Analyzer Operation Manual
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Sample gas flow in the T200 analyzer is not a directly measured value, but is rather
calculated based on the measured pressure differential across the sample gas critical
flow orifice. Specifically, the upstream reading of the sample pressure sensor is
compared to the downstream pressure reading of the vacuum pressure sensor and this
differential is used, by the analyzer‟s CPU, to derive the gas flow rate through the
reaction cell.

The results of this calculation are viewable from the instruments front panel via the
test function
SAMP FLW.

Since this is a calculated value and not a measured reading there is no
corresponding SIGNALI/O function.
In contrast to the sample gas flow, the ozone flow is measured with a mass flow sensor,
which is mounted on the flow/pressure sensor PCA just behind the PMT sensor
assembly. Pneumatically, it lies between the Sample dryer and the O
sensor has a full scale range of 0-1000 cm³/min and can be calibrated through software
to its span point (Section 9.7).
Since the flow value displayed on the front panel is an actual measurement (and not a
calculated value), short term variability in the measurement may be higher than that of
the sample flow, which is based on a calculation from (more stable) differential
pressures. On the other hand, any sustained drift, i.e. long-term change, in the ozone
flow rate may usually indicate a flow problem.
This information is used to validate the O

If the flow rate exceeds ±15% of the nominal flow rate (80 cm³/min), a warning
message OZONE FLOW WARNING is displayed on the analyzer's front panel (see
Section 4.1.2) and the O

A second warning, OZONE GEN OFF is also displayed.

This flow measurement is viewable through instrument's front panel display as the
test function OZONE FL and the SIGNAL I/O function OZONE_FLOW.
As with all other test parameters, we recommend to monitor the ozone flow over time
for predictive diagnostics and maintenance evaluation.
gas flow rate.
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generator is turned off.
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Principles of Operation
. This mass flow
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