WMA-5 Operation Manual V. 1.01
37
CO
2
Calibration
This menu allows the user to recalibrate the CO2 gas analyzer.
Before calibrating, confirm that:
•
The absorber column is properly seated in its manifold
•
The soda lime is fresh in the Zero Column.
•
The WMA-5 has been on for at least 30 minutes.
•
The Gas Out port is unobstructed.
Calibration
CO2
Conc (ppm) Button
CO
2
concentration (ppm) of the calibration reference gas.
Entering a value will begin the calibration process
Actual CO2
The current CO2 Reading based on the Scale Factor
CO2 Scale Factor
The current Scale Factor being used
Stop Button
Returns to the Calibration Menu.
Connecting Calibration Gas to the WMA-5
During calibration, the signal from the CO
2
detector is referenced against a gas of known CO
2
concentration. The WMA-5 calibration procedure uses two reference points:
1. Zero CO
2
(generated from air that has been scrubbed through soda lime).
2. Span Gas (a user-defined CO
2
concentration, normally a very accurate (+/- 1% accuracy),
certified cylinder of CO
2
composition).
It is therefore vital that both of these references are accurate. For greater accuracy, cylinder mixtures
should be accurate to +/- 1% and traceable to NIST standards. The zero gas will only be accurate if the
soda lime in the absorber column is fresh.
Assuming that a calibration gas mixture is used to calibrate the WMA-5, follow these instructions:
1. To avoid excess pressure in the sample cell and possible damage to the analyzer, you must connect
the sample line with a “T” piece between the calibration gas mixture and the gas inlet port on the
WMA-5 as follows: