Teledyne GFC-7000T - Trace CO2 Analyzer - manual - Manual (Page 179)

Calibration Procedures Model GFC7000TA Carbon Dioxide Analyzer
Teledyne Analytical Instruments 161
7. CALIBRATION PROCEDURES
This contains a variety of information regarding the various methods for calibrating a Model GFC 7000TA
CO
2
Analyzer as well as other supporting information.
NOTE
The procedures in this assume that the calibration password feature is disabled
(the instruments default state). If it is enabled a password prompt screen (See
Section 6.9) will appear after the CAL, CALZ or CALS buttons are pushed but before
the instrument enters the associated calibration mode.
7.1. Before Calibration
The calibration procedures in this assume that the Range Type, Range Span and units of measure have
already been selected for the analyzer. If this has not been done, please do so before continuing (See
Section 6.8 for instructions).
All Gas lines should be PTFE (Teflon), FEP, glass, stainless steel or brass.
NOTE
If any problems occur while performing the following calibration procedures, refer
to Section 11 of this manual for troubleshooting tips.
7.1.1. Zero Air and Span Gas
To perform the following calibration you must have sources for zero air and span gas available.
Zero Air is similar in chemical composition to the Earth’s atmosphere but scrubbed of all components that
might affect the analyzer’s readings. Zero air should contain less than 25 ppb of CO
2
and other major
interfering gases such as CO and Water Vapor. It should have a dew point of -5 C or less
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% of the full measurement range.
If Span Gas is sourced directly from a calibrated, pressurized tank, the gas mixture should be CO
2
mixed
with Zero Air or N
2
at the required ratio.
Zero air generators that condition ambient air by drying and removal of pollutants are available on the
commercial market such as the Teledyne Instruments Model 701 Zero Air Generator. We recommend
this type of device, in conjunction with bottled N
2
for generating zero air.