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Model 9110T NOx Analyzer Troubleshooting & Service
Teledyne Analytical Instruments 297
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 T700.
Note There must be a minimum of 10% more NO than O3 produced.
Example, if the Ozone concentration used is 400 ppb then the NO
concentration must be used must be 440 ppb or more.
PART 1: PREPARATION
1. Leak check machine to ensure that there are no leaks in the analyzer.
2. Calibrate the instrument at the same NO span gas value as being used in this
method.
For this example 450 ppb NO span gas
3. If you have input a converter efficiency (CE) factor into the instrument firmware (see
12.7.10.3 ) other than 100%, change this back to 100% for the duration of this test.
(CAL>CONC>CONV>SET).
PART 2: DETERMINE THE AMOUNT OF NO OUTGASSED BY THE NO2 NO
CONVERTER.
4. Bypass the NO2 NO converter by placing a short piece of tubing in the gas
stream in place of the converter.
5. Perform a straight dilution with 445 ppb NO gas & air as a diluent gas.
6. Input the NO gas into the analyzer.
7. Allow the machine to stabilize & write down the NOx value on line 2 of GPT data
sheet (Section 12.7.11.1).
8. Remove the converter bypass so that the NO gas is flowing through the NO2 NO
converter
9. Allow the machine to stabilize.
10. Write down your NOx value on your data sheet on lines 3 AND line 5 of the GPT
data sheet.
11. Subtract line 2 from line 3 & write that number down on line 4. Also write the NO
value on line 8 of the data sheet.
The specification shown on the data sheet is the value that is used by TAI when performing
the procedure on new NO
2
NO converters.
Older NO
2
NO converters might outgas a bit more NO, therefore a slightly wider
specification might be in order.
If this value is a constant or changes only slightly over time, this is not a problem the
machine will calibrate this out.