Teledyne T200, Operation Manual, Page: 248 / 425

Troubleshooting & Service Teledyne API
– T200 NO/NO2/NOx Analyzer Operation Manual
246
12.5.8. DISCREPANCY BETWEEN NO AND NOX SLOPES
If the slopes for NO and NO
X
are significantly different after software calibration (more
than 1%), consider the following three problems:

NO
2
impurities in the NO calibration gas. NO gases often exhibit NO
2
on the order
of 1-2% of the NO value.

This will cause differences in the calibration slopes. If the NO2 impurity in NO is
known, it can easily be accounted for by setting the expected values for NO and
NO2 accordingly to different values, e.g., 448 ppb NO and 450 ppb NOX.

This problem is worse if NO gas is stored in a cylinder with balance air instead
of balance gas nitrogen or large amounts of nitrous oxide (N2O).

The oxygen in the air slowly reacts with NO to yield NO2, increasing over time.

The expected concentrations for NO and NO
X
in the calibration menu are set to
different values.

If a gas with 100% pure NO is used, this would cause a bias.

See Section 9.2.3.1 on how to set expected concentration values.

The converter efficiency parameter has been set to a value not equal to 1.000 even
though the conversion efficiency is 1.0.

The actual conversion efficiency needs to match the parameter set in the CAL
menu.

See Section 9.1.4 for more information on this feature.
An instrument calibration with the IZS option (and expected concentrations set to the
same amount) will always yield identical slopes for NO and NO
X
, as the instrument
measures only NO
X
and assumes NO to be the same (with NO
2
being zero).
12.6. OTHER PERFORMANCE PROBLEMS
Dynamic problems (i.e. problems that only manifest themselves when the analyzer is
monitoring sample gas) can be the most difficult and time consuming to isolate and
resolve. The following section provides an itemized list of the most common dynamic
problems with recommended troubleshooting checks and corrective actions.
12.6.1. EXCESSIVE NOISE
Excessive noise levels under normal operation usually indicate leaks in the sample
supply or the analyzer itself. Ensure that the sample or span gas supply is leak-free and
carry out a detailed leak check as described earlier in this chapter.
Another possibility of excessive signal noise may be the preamplifier board, the high
voltage power supply and/or the PMT detector itself.

Contact the factory on troubleshooting these components.
12.6.2. SLOW RESPONSE
If the analyzer starts responding too slow to any changes in sample, zero or span gas,
check for the following:

Dirty or plugged sample filter or sample lines.

Sample inlet line is too long.
06858E DCN7057