Teledyne 9110T - Nitrogen Oxides Analyzer - Manual (Page 58)

Model 9110T NOx Analyzer Getting Started
Teledyne Analytical Instruments 58
SPAN GAS FOR MULTIPOINT CALIBRATION
Some applications, such as EPA monitoring, require a multipoint calibration where span gases of
different concentrations are needed. We recommend using an NO gas of higher concentration combined
with a gas dilution calibrator such as a Teledyne Model 700E. This type of calibrator mixes a high
concentration gas with zero air to accurately produce span gas of the desired concentration. Linearity
profiles can be automated with this model and run unattended overnight.
If a dynamic dilution system such as the Teledyne Model 700 is used to dilute high concentration gas
standards to low, ambient concentrations, ensure that the NO concentration of the reference gas matches
the dilution range of the calibrator.
Choose the NO gas concentration so that the dynamic dilution system operates in its mid-range and not
at the extremes of its dilution capabilities.
EXAMPLE:
 A dilution calibrator with 10-10000 dilution ratio will not be able to accurately dilute a 5000 ppm NO
gas to a final concentration of 500 ppb, as this would operate at the very extreme dilution setting.
 A 100 ppm NO gas in nitrogen is much more suitable to calibrate the 9110T analyzer (dilution ratio
of 222, in the mid-range of the system’s capabilities).
Zero Air generator (IZS) has a limited accuracy of about ±5%.
While NO2 permeation tubes may be sufficient for informal calibration
checks, they are not approved by the US EPA as calibration sources for
performing actual calibration of the analyzer.