Teledyne API Model 200AH NOX Analyzer Instruction Manual, 06492, Rev. G2
5-15
5.2.2. CAL, CALS, CALZ, Calibration Functions
The calibration and zero/span checking of the M200AH analyzer is treated in detail in Section 7,
Table 7-1 summarizes types of calibration.
5.2.2.1. CAL, CALS, CALZ
The CAL, CALS, and CALZ keys control the calibration functions of the analyzer. In the CAL
mode the analyzer can be calibrated with zero/span gas coming in through the sample input port
on the rear panel. If the analyzer is equipped with the Zero/Span valve option, the CALZ and
CALS buttons operate the Zero/Span valves. The setup of this option is covered in Section 6.2,
and operation is explained in Section 7.
5.2.2.2. Gas To Cal
For units equipped with the Oxygen Sensor Option, depressing the CAL key will cause the
instrument to prompt for which gas sensor to calibrate; NOX or O2. After the desired gas is
selected, the instrument will display ZERO, SPAN, and CONC keys as described below.
5.2.2.3. Zero
Pressing the ZERO key along with ENTR will cause the instrument to adjust the OFFSET value
of the internal formulas so that the instrument reads zero. The M200AH allows zero adjustment
over a limited range of signal levels, therefore the signal does not have to be exactly zero for the
instrument to do a zero cal. The instrument will not, however, allow a zero cal on any signal
level, therefore it is not possible to zero the instrument with high concentrations of span gas in
the reaction cell. If the ZERO key does not come on as expected, check Section 9.2.9.
5.2.2.4. Span
Pressing the SPAN key along with ENTR will cause the instrument to adjust the SLOPE value of
the internal formula so the instrument displays the span value. The expected NOX, NO span
concentrations must be entered before doing a SPAN calibration. See Table 7-3.
Like the Zero calibration, the Span cal cannot be done with any concentration of span gas. If
signal level is outside certain limits the SPAN key will not be illuminated. If you encounter this
condition see Section 9.2.8. It is also possible at low levels of span concentration that BOTH the
ZERO and SPAN keys might be on, thus allowing you to either zero or span the instrument. In
this case care must be taken to perform the correct operation or the analyzer can become miss-
calibrated.