Teledyne GFC 7001EM operation manual Data Recording Devices, Traceability

Calibration Procedures Model GFC7001E Carbon Dioxide Analyzer

9.1.2.2.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 N2 at the required ratio.

For oxygen measurements using the optional O2 sensor, we recommend a reference gas of 21% O2 in N2.

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

Generally, O2 concentration in dry, ambient air varies by less than 1%.

9.1.2.3.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.

Table 9-1: NIST-SRMs 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
27452	CO2	in N2	16% by weight

1 Used to calibrate optional O2 sensor.

2 Used to calibrate optional CO2 sensor.

NOTE

It is generally a good idea to use 80% of the reporting range for that channel for 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

40.0PPM

9.1.3.DATA RECORDING DEVICES

A strip chart recorder, data acquisition system or digital data acquisition system should be used to record data from the serial or analog outputs of the GFC 7001E/EM.

If analog readings are used, the response of the recording system should be checked against a NIST traceable voltage source or meter.

Data recording devices should be capable of bi-polar operation so that negative readings can be recorded.

For electronic data recording, the GFC 7001E/EM provides an internal data acquisition system (iDAS), which is described in detail in Section 7.1

APICOM, a remote control program, is also provided as a convenient and powerful tool for data handling, download, storage, quick check and plotting (see Section 8.4).

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