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Teledyne API – Model T300/T300M CO Analyzer Getting Started
75
If the analyzer is NOT equipped with the optional CO
2
sensor, zero air should be
scrubbed of CO
2
as well, as this gas can also have an interfering effect on CO
measurements.
For analyzers without an IZS or external zero air scrubber option, a zero air generator
such as the Teledyne API Model T701 can be used.
S
PAN GAS
Span gas is a gas specifically mixed to match the chemical composition of the type of
gas being measured at near full scale of the desired measurement range. In the case of
CO measurements made with the T300 or T300M Analyzer, it is recommended that you
use a span gas with a CO concentration equal to 80-90% of the measurement range for
your application.
EXAMPLE: If the application is to measure between 0 ppm and 500 ppb, an appropriate
span gas concentration would be 400-450 ppb CO in N2.
Cylinders of calibrated CO gas traceable to NIST-Standard Reference Material
specifications (also referred to as SRMs or EPA protocol calibration gases) are
commercially available. Table 3-12 lists specific NIST-SRM reference numbers for
various concentrations of C
O
.
Table 3-12: NIST-SRM's Available for Traceability of CO Calibration Gases
NIST-SRM TYPE NOMINAL CONCENTRATION
1680b CO in N
2
500 ppm
1681b CO in N
2
1000 ppm
2613a CO in Zero Air 20 ppm
2614a CO in Zero Air 45 ppm
2659a
1
O
2
in N
2
21% by weight
2626a CO
2
in N
2
4% by weight
2745* CO
2
in N
2
16% by weight
1
Used to calibrate optional O
2
sensor.
2
Used to calibrate optional CO
2
sensor.
SPAN GAS FOR MULTIPOINT CALIBRATION
Some applications, such as EPA monitoring, require a multipoint calibration procedure
where span gases of different concentrations are needed. We recommend using a bottle
of calibrated CO gas of higher concentration in conjunction with a gas dilution calibrator
such as a Teledyne API’s T700. This type of calibrator precisely mixes a high
concentration gas with zero air (both supplied externally) to accurately produce span gas
of the correct concentration. Linearity profiles can be automated with this model and
run unattended over night.
06864B DCN6314