Teledyne M300EM operation manual Span Gas

Teledyne API – Technical Manual - Model 300E Family CO Analyzers Getting Started

3.4.1.2.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. In the case of CO measurements made with the M300E/EM 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.

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 M700. 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.

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 3-7lists specific NIST-SRM reference numbers for various concentrations of CO.

Table 3-7: NIST-SRM's Available for Traceability of CO Calibration Gases

NIST-SRM	TYPE	NOMINAL
		CONCENTRATION
1680b	CO in N2	500 ppm
1681b	CO in N2	1000 ppm
2613a	CO in Zero Air	20 ppm
2614a	CO in Zero Air	45 ppm
2659a1	O2 in N2	21% by weight
2626a	CO2 in N2	4% by weight
2745*	CO2 in N2	16% by weight

1 Used to calibrate optional O2 sensor.

2 Used to calibrate optional CO2 sensor.

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