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Model 200E Instruction Manual Calibration Procedures
7.5. Calibration with IZS Option
When using the IZS option to calibrate the M200E, the analyzer’s CAL_ON_NO2 feature
must be turned on. This feature enables a continuous zero gas flow across the IZS
permeation tube and through the NO
2
converter (Figure 3-11). It also programs the
analyzer to use the NO output from the NO
2
converter to calibrate the span value of both
NO and NO
X
.
NOTE
The IZS with NO
2
permeation tube has a limited accuracy of about ±5%. Whereas
this may be sufficient for informal calibration checks, this method of calibration is
not approved by the US EPA as a calibration source.
This feature should only be enabled when a span calibration or calibration check is
performed. While
CAL-ON-NO2 is enabled, the NO
2
concentration will always be reported
as zero. This is because the gas is continuously routed through the NO
2
converter and the
analyzer’s firmware simulates calibration with NO gas. Since the instrument sees the same
concentration of NO during both NO and NO
X
cycles, it reports an NO
2
concentration of zero.
Table 7-1: IZS Option Valve States with CAL_ON_NO
2
Turned ON
Valve Condition Valve Port Connections
Sample/Cal Open to zero/span valve 1
!
2
Zero/Span Open to SPAN GAS inlet 1
!
2
NO/NOx Valve Open to NO2 converter 1
!
2
AutoZero Valve Cycles normally N/A
Performing a manual calibration of the analyzer with an IZS option installed is similar to the
method described in Section 7.4, except that both zero air and span gas are supplied to the
analyzer from ambient air through the zero gas inlet.
1. Connect the sources of zero air and span gas as shown in Figure 7-3.
Figure 7-3: Pneumatic Connections for Manual Calibration Checks with IZS
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