Teledyne API - Model T200H/T200M Operation Manual
Principles of Operation
279
8.3.5. OZONE GAS AIR FLOW
The excess ozone needed for reaction with NO in the reaction cell is generated inside the
analyzer because of the instability and toxicity of ozone. Besides the ozone generator
itself, this requires a dry air supply and filtering of the gas before it is introduced into the
reaction cell. Due to its toxicity and aggressive chemical behavior, O
3
must also be
removed from the gas stream before it can be vented through the exhaust outlet.
In contrast to the sample flow, the ozone flow is measured with a mass flow sensor,
which is mounted on the pneumatic sensor board, just behind the PMT sensor assembly.
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 4.13.7.5). As the flow value displayed on the
front panel is an actual measurement (and not a calculated value), the flow variability may
be higher than that of the sample flow, which is based on a calculation from (more stable)
differential pressures. On the other hand, the drift, i.e. long-term change, in the ozone
flow rate may be higher and usually indicates a flow problem. As with all other test
parameters, we recommend to monitor the ozone flow over time for predictive diagnostics
and maintenance evaluation.
CAUTION
Ozone (O
3
) is a toxic gas. Obtain a Material and Safety Data Sheet (MSDS) for this
gas. Read and rigorously follow the safety guidelines described there. Always make
sure that the plumbing of the O
3
generation and supply system is maintained and
leak-free.
07270D DCN7141