Teledyne API Model 200A NOX Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
7.9 Calibration of Independent Ranges or Autoranging
There are additional considerations when AutoRange or Independent Ranges are selected. The
M200A uses one physical range of 0-2000 ppb to cover all EPA concentration ranges. The
dynamic range of the internal hardware and computer software is sufficient to cover this entire
range. Internally the range only scales parts of the 0-2000 ppb physical range to cover the
voltage range selected for the analog outputs.

7.9.1 Zero Calibration with AutoRange or Independent Range

Having one physical range to cover all EPA concentration ranges simplifies zero calibration. No
matter what AutoRange or Independent Range values are selected the values computed from a
zero calibration are the same. Therefore no special precautions need to be taken when doing a
zero calibration.

7.9.2 Span Calibration with AutoRange or Independent Range

Observe the following guidelines when calibrating in AutoRange or Independent Range.
1. When doing a span calibration of the M200A use 80% of the highest of the ranges. This
will result in the most accurate calibration.
2. When selecting concentrations for the NO/NOx or NO2 (GPT) dynamic calibrations use
80% of the highest AutoRange or the highest Independent Range. This will produce the most
accurate calibration.
3. If the calibration data is obtained from the RS-232 port or from the front panel display,
no special changes are necessary if the instrument is in AutoRange or Indep. Range. This is
because the internal hardware and software has sufficient dynamic range to cover the entire
EPA equivalent range, also those features only affect the analog outputs.
4. If using the analog outputs and a chart recorder or datalogger, be sure to note when
AutoRange occurs so that the correct range is used. With Independent Ranges, change the
ranges so that all ranges are equal to the highest range so that all calibration data is on scale.
5. Calibration curves or relationships should be obtained for each range used.
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