Teledyne T200, Operation Manual, Page: 264 / 425

Troubleshooting & Service Teledyne API
– T200 NO/NO2/NOx Analyzer Operation Manual
262

Recalculate the converter efficiency (see previous section)

Accuracy of NO
2
source (GPT or gas tank standard).

NO
2
gas standards are typically certified to only ±2% and often change in
concentrations over time. You should get the standard re-certified every year.

If you use the GPT calibration, check the accuracy of the ozone source.

Age of the converter.

The NO
2
converter has a limited operating life and may need to be replaced
every ~3 years or when necessary (e.g., earlier if used with continuously high
NO
2
concentrations).

We estimate a lifetime of about 10000 ppm-hours (a cumulative product of the
NO
2
concentration times the exposure time to that concentration).

This lifetime heavily depends on many factors such as:

Absolute concentration (temporary or permanent poisoning of the
converter is possible).

Sample flow rate and pressure inside the converter.

Converter temperature.

Duty cycle.

This lifetime is only an estimated reference and not a guaranteed lifetime.

In some cases with excessive sample moisture, the oxidized molybdenum metal
chips inside the converter cartridge may bake together over time and restrict air flow
through the converter, in which case it needs to be replaced.

To avoid this problem, we recommend the use of a sample gas conditioner
(Section 3.3.2.6).

Section 11.3.8 describes how to replace the NO
2
converter cartridge.

With no NO
2
in the sample gas and a properly calibrated analyzer, the NO reading
is negative, while the NO
2
reading remains around zero.

The converter is destroying NO and needs to be replaced.

With no NO
2
in the sample gas and a properly calibrated analyzer, the NO
X
reading
is significantly higher than the actual (gas standard) NO concentration.

The converter is producing NO
2
and needs to be replaced.
12.7.11. DETERMINING CE BY SIMPLIFIED GPT CALIBRATION
This section describes how to determine the NO2

NO converter‟s efficiency using a
GPT method where the actual concentration of ozone is not a factor in the accuracy of
the calculation.

This procedure is based on the Code of Federal Regulations, Title 40, Chapter I,
subchapter C, Part 50, Appendix F.

In the following example a reference point of 450 ppb NO gas will be used. This is
only an example. Any other reference points within measurement range of the
instrument may be used.

For this procedure use a calibrated O
3
generator, such as a Teledyne API's T700.
Note
There must be a minimum of 10% more NO than O
3
produced.
Example, if the Ozone concentration used is 400 ppb then the NO concentration
must be used must be 440 ppb or more.
06858E DCN7057