Teledyne 9110T instruction manual 13.2.4.4. O3 Supply Air Flow Sensor

Model 9110T NOx Analyzer Principles of Operation

∙Since this is a calculated value and not a measured reading there is no corresponding SIGNALI/O function.

13.2.4.4. O3 Supply Air Flow Sensor

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 Perma Pure® dryer and the O3. This mass flow 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 O3 gas flow rate.

∙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 O3 generator is turned off.

∙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.

Teledyne Analytical Instruments 337