Teledyne API Model 200AU NOX Analyzer Instruction Manual, 02293, Rev. F
7-6
7.2 Manual Zero/Span Check or Calibration with Zero/Span Valves Option
The Zero/Span valve option can be operated from the front panel keyboard. In the Zero/Span
valve option the zero and span gas come into the valves through ports on the rear panel of the
instrument.
Table 7-5: Manual Zero Calibration Procedure - Z/S Valves
Step Number Action Comment
1. Press CALZ The analyzer enters the zero calibrate mode. This switches the
sample/cal and zero/span valves to allow zero gas to come in
through the zero gas inlet port in the rear panel. When the
CALZ button is pressed, the adaptive filter is activated. This
allows the instrument to respond rapidly to concentration
changes regardless of their magnitude.
2. Wait 10 min Wait for reading to stabilize at zero value.
3. Press ZERO If you change your mind after pressing ZERO, you can still
press EXIT here without zeroing the instrument.
4. Press ENTR Pressing ENTR actually changes the calculation equations,
forcing the reading to zero.
5. Press EXIT M200AU returns to sample mode. Immediately after
calibration, readings do not go into the DAS averages.
Refer to Table 7-3 to enter expected NO and NOx values.