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Teledyne API Model 200AU NO
X
Analyzer Instruction Manual, 02293, Rev. F
5-13
Sample Pressure
The pressure in the sample inlet line is measured by a solid state pressure sensor which measures
absolute pressure. This pressure typically runs 0.5" or so below atmospheric pressure due to the
pressure drop in the sample inlet lines and valves.
NO
x
, NO Slope and Offset Values
The coefficients of 2 (NO
x
and NO) straight line equations (y = mx + b) determine the
calibration of the M200AU. The slope parameter(m) can be thought of as a gain term which
determines the steepness of the calibration curve. The offset parameter (b) compensates for
differences in the background signal of the NO and NO
x
channels.
The values of these parameters can be used to determine the quality of the calibration. These 4
parameters contain valuable information about the quality and validity of the calibration. For
example, the NO and NO
x
slope values should not differ by more than .1 from each other. Larger
values indicate a flow imbalance such as a leak or problems with the molybdenum converter.
Refer to Section 7.8 Calibration Quality for details on how to use these values.
Time
This is an output of the M200AU's internal time of day clock.
5.2.2 CAL, CALS, CALZ, Calibration Functions
The calibration and zero/span checking of the M200AU analyzer is treated in detail in Section 7,
Table 7-1 summarizes types of calibration. The basic function of each of these keys is described
here. When any of the CAL buttons are pressed (or whenever the instrument enters the CAL
mode), the adaptive filter is activated. This allows the instrument to respond rapidly to
concentration changes regardless of their magnitude.
5.2.2.1 CAL, CALS, CALZ
These keys control the calibration functions of the analyzer. In the CAL mode the analyzer can
be calibrated without switching on the zero valve or the span valve. If the analyzer has the
Zero/Span valve option, there will be CALZ and CALS buttons also. These buttons operate the
Zero/Span valves. The setup of these options is covered in Section 6.3, and operation is
explained in Section 7.