Operation
EGM-4 Operator's Manual – Version 4.19
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3CAL
To calibrate the EGM-4, press key 3.
The EGM-4 will display a value. Before proceeding, it is critical that:
• The absorber column is properly seated in its manifold
• The soda lime is fresh.
• The EGM-4 has been on for at least 30 minutes.
• The Gas Out port is unobstructed.
• No accessories or sensors can be connected to the EGM-4 when recalibrating.
Connecting Calibration Gas To The EGM-4
During calibration, the signal from the CO
2
detector is referenced against a gas of known CO
2
concentration. The EGM-4 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 cylinder of certified 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 EGM-4, 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 In” port on the EGM-4 as follows:
CORRECT (Y-N)?
CO
2
Gas
Cylinder
Regulator
In-line “T” piece
to vent excess
Port
Valve
Excess gas of
approx. 250 ml/min
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