Table of Contents
Advertisement
Calibration Procedures
9.1.1.1. ZERO AIR
9.1.1.2. SPAN GAS
9.1.1.3. CALIBRATION GAS STANDARDS AND TRACEABILITY
It is generally a good idea to use 80% of the reporting range for that channel for
Note
the span point calibration.
For instance, if the reporting range of the instrument is set for 50.0 PPM, the
proper span gas would be 40.0 PPM.
198
Zero air or zero calibration gas is defined as a gas that is similar in chemical
composition to the measured medium but without the gas to be measured by the
analyzer.
For the T300/T300M zero air should contain less than 25 ppb of CO and other major
interfering gases such as CO and Water Vapor. It should have a dew point of -5°C or
less.
If your application is not a measurement in ambient air, the zero calibration gas should
be matched to the composition of the gas being measured.
•
Pure nitrogen (N
) can be used as a zero gas for applications where CO is
2
measured in nitrogen.
•
If your analyzer is equipped with an external zero air scrubber option, it is capable of
creating zero air from ambient air.
For analyzers without the zero air scrubber, a zero air generator such as the Teledyne
API's T701 can be used. Please visit the company website for more information.
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.
recommended that the span gas used have a concentration equal to 80-90% of the full
measurement range.
If Span Gas is sourced directly from a calibrated, pressurized tank, the gas mixture
should be CO mixed with Zero Air or N
For oxygen measurements using the optional O
of 21% O
in N
.
2
2
•
For quick checks, ambient air can be used at an assumed concentration of 20.8%.
•
Generally, O
concentration in dry, ambient air varies by less than 1%.
2
All equipment used to produce calibration gases should be verified against standards of
the National Institute for Standards and Technology (NIST).
traceability, we recommend to acquire cylinders of working gas that are certified to be
traceable to NIST Standard Reference Materials (SRM). These are available from a
variety of commercial sources.
Table 9-1:
NIST-SRMs Available for Traceability of CO Calibration Gases
NIST-SRM
Type
680b
CO in N
2
1681b
CO in N
2
2613a
CO in Zero Air
2614a
CO in Zero Air
2659a1
O
in N
2
2
2626a
CO
in N
2
2
27452
CO
in N
2
2
1
Used to calibrate optional O
Teledyne API – Model T300/T300M CO Analyzer
at the required ratio.
2
2
Nominal Concentration
500 ppm
1000 ppm
20 ppm
45 ppm
21% by weight
4% by weight
16% by weight
2
sensor.
Used to calibrate optional CO
2
sensor, we recommend a reference gas
To ensure NIST
sensor.
2
06864B DCN6314
It is
Advertisement
Table of Contents
Troubleshooting
