Teledyne t320u Manuale Utente

Calibration Procedures 

Teledyne API – Model T300/T300M CO Analyzer 

198 

9.1.1.1. ZERO AIR 

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

2

) can be used as a zero gas for applications where CO is 

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. 

9.1.1.2. SPAN 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.  It is 

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

2

 at the required ratio. 

For oxygen measurements using the optional O

2

 sensor, we recommend a reference gas 

of 21% O

2

 in N

2

.   

  For quick checks, ambient air can be used at an assumed concentration of 20.8%.   
 Generally, 

O

2

 concentration in dry, ambient air varies by less than 1%. 

9.1.1.3. CALIBRATION GAS STANDARDS AND TRACEABILITY 

All equipment used to produce calibration gases should be verified against standards of 

the National Institute for Standards and Technology (NIST).  To ensure 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. 

680b 

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 

2659a1 O

2

 in N

2

 

21% by weight 

2626a CO

2

 in N

2

 

4% by weight 

27452 CO

2

 in N

2

 

16% by weight 

1

 Used to calibrate optional O

2 

 sensor. 

2

 Used to calibrate optional CO

2

 sensor. 

06864B DCN6314