Teledyne API Model 200AH NOX Analyzer Instruction Manual, 06492, Rev. G2
5-14
If the analyzer is equipped with the molybdenum converter option the TEST function will report
MOLY TEMP, the temperature setpoint will be 315 10°C.
If the analyzer is equipped with the Model 501 external converter option, the converter
temperature is shown on the front panel of the M501. The TEST function O3KL will report the
temperature of the catalytic ozone killer located inside the converter can.
Reaction Cell Pressure (RCEL)
The pressure in the reaction cell is measured by a solid state pressure sensor which measures
absolute pressure. Absolute pressure was chosen because it is an unambiguous measure of cell
pressure. This pressure will vary depending on several things.
1. The type of pump attached to the analyzer.
2. Variations in local weather will cause a 0.3 in-Hg change in pressure.
3. The altitude of the analyzer will cause the cell pressure to change.
Nominal values are 3 to 10 in-Hg-A. Typical reading is about 5 in-Hg-A at sea level for the
standard pump.
Sample Pressure (SAMP)
The sample pressure is measured by one of the pressure sensors on the sensor board. The sample
pressure typically runs slightly below atmospheric pressure. Sample pressure will change with
varying atmospheric pressure (like the weather) because the sensor is an absolute pressure
sensor. It will also change with altitude.
NOX, NO, O2 Slope and Offset Values (NOX SLOPE, NOX OFFS, NO SLOPE, NO OFFS,
O2 SLOPE, O2 OFFS)
The slope (m) and intercept (b) coefficients of straight line equations (y = mx + b) determine the
calibration of the M200AH. The slope parameter(m) can be thought of as a gain term which
determines the steepness of the calibration curve. The offset (b) parameter compensates for
differences in the background signal of the NO and NOX channels. This is primarily due to the
background of the converter.
These parameters contain valuable information about the quality and validity of the calibration.
For example the NO and NOX slope values should not differ by more than 0.1 from each other.
Larger values indicate a flow imbalance such as a leak or problems with the converter. Refer to
Section 7.10 Calibration Quality for details on how to use these values.
Time (TIME)
This is the output of the internal time of day clock.