5.0 CALIBRATION AND ZERO/SPAN CHECKS
Unlike most NOx analyzers, the M200EU with the NOy option does not have a sample inlet port on the rear panel of the M200EU. The sample port is located on the External Converter; therefore Zero/Span calibration is different than a normal NOx instrument. If a fitting is located at the sample port the analyzer is equipped with the Zero/Span option.
Follow the steps in the M200E/EU manual to:
a.Enter the expected NO and NOy span gas concentrations in the M200EU.
b.Do the zero calibration procedure
c.Do the span calibration procedure
The analyzer always routes the zero/span gas through the external converter. In standard configuration, the calibration gas needs to be input at the “Cal in” port of the M501 Pump pack. When Zero/Span valve option is installed, zero and span gases are to be provided at the M200EU Zero and Span ports. In all cases, the calibration gas delivered must be under a small amount of pressure
Calibration gas must be provided for both the bypass system and the M200EU analyzer. Flow requirements are 0.80 LPM for NO bypass, 0.80 LPM for NOy bypass and 1 LPM for the M200EU. Calibration gas flow must be in sufficient excess (~4 LPM) to prevent any ambient air from entering the SAMPLE port on the pole.
The maximum 50 ft length of tubing between the bypass Pump Module and the remote Moly converter has been proven to generate too much backpressure for some brands of calibrators. Experience to date is that while NO calibration is correct, GPT can be incorrect due to errors in dilution of the ozone.
We strongly recommend that SPAN CALIBRATION be done with NO span gas. SPAN CHECKS can be done with either NO only, NO2 only or a mixture of NO and NO2 (GPT).
Zero air used for all calibration procedures, including GPT, should have <1 ppt NO and NO2, less than 1 ppt of major interferents such as SO2, NH3, hydrocarbons and a dew point of
05386 Rev. D | 15 |
