Teledyne T200, Operation Manual, Page: 51 / 425

Teledyne API
– T200 NO/NO
2
/NO
X
Analyzer Operation Manual Getting Started
49

For analyzers without the external zero air scrubber, a zero air generator, such as
those offered by Teledyne API, can be used. Please visit the company website for
more information.
C
ALIBRATION
(S
PAN
) G
AS
Calibration gas is specifically mixed to match the chemical composition of the type of
gas being measured at near full scale of the desired reporting range. To measure NO
X
with the T200, it is recommended that the span gas have an NO concentration equal to
80% of the measurement range for your application.
EXAMPLE:

If the application is to measure NO
X
in ambient air between 0 ppm and 500 ppb, an
appropriate span gas would be 400 ppb.

If the application is to measure NO
X
in ambient air between 0 ppm and 1000 ppb,
an appropriate span gas would be 800 ppb.
Even though NO gas in nitrogen could be used as a span gas, the matrix of the balance
gas is different and may cause interference problems or yield incorrect calibrations.

The same applies to gases that contain high concentrations of other compounds
(for example, CO
2
or H
2
O).

The span gas should match all concentrations of all gases of the measured medium
as closely as possible.
Cylinders of calibrated NO
x
and NO gas traceable to NIST standards specifications (also
referred to as EPA protocol calibration gases or Standard Reference Materials) are
commercially available.
S
PAN
G
AS FOR
M
ULTIPOINT
C
ALIBRATION
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 API 700-Series
Model. 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 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 T200 analyzer
(dilution ratio of 222, in the mid-range of the system’s capabilities).
06858E DCN7057