Getting Familiar With The EGM-4
EGM-4 Operator's Manual – Version 4.19
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corrects for such things as sample cell contamination, source aging, detector sensitivity and
changes in electronics.
Soda Lime
Soda lime is used to remove CO
2
from air entering the EGM-4. It is supplied as self-
indicating granules (1-2.5mm) that turn from green to brown as it becomes exhausted. The
contents of the absorber column should be replaced when it is 2/3rds exhausted (brown).
Soda Lime cannot be regenerated and should be discarded when exhausted. For accurate
measurements and calibration, it is absolutely critical that the EGM-4 absorber column is not
exhausted. If the soda lime is becoming exhausted, it will cause the ZERO to be performed
on non-ZERO air causing an error in the calibration.
When exhausted, the Soda Lime Cap should be removed along with the foam filter pad (with
the EGM-4 facing upwards) and the contents discarded. When replacing the soda lime, we
recommend using a funnel to ensure that the desiccant fills the absorber column. Leave
approximately 1” from the end of the column to allow the foam pad and cap to be refitted.
! CAUTION !
WASH YOUR HANDS AFTER HANDLING SODA LIME
Keypad
The custom, tactile keypad consists of 12 keys. There are ten keys that are labelled
0-9
.
Also, there are a few keys that have additional functions. The
Y/R
(Yes/Record) key is used
to accept settings and to record measurements. In addition, the
Y/R
key is pressed to
advance from one display to the next. The
N
key is normally used to return to the Main Menu
from Measurement Mode, reject settings or to step back through the menus. The
8/X
key is
used to toggle from one display to another in Measurement Mode.
LCD Display
The EGM-4 features a 2x16 character, backlit LCD display.
Gas Ports
There are two barb fittings located on the top of the EGM-4. Each barb fitting is designed for
use with 1/8” (.125”) ID tubing. One barb fitting is labelled “Gas In” and the other “Gas Out”.
The sampling line should be fitted to the “Gas In” port using 1/8” tubing. The “Gas Out” line
should be left open to atmosphere to allow the sample air to exhaust without restriction. Note,
for closed system measurements with our SRC-1 Soil Respiration Chamber or CPY-2 Canopy
Asssimilaton Chamber, one gas line is connected to the “Gas In” port and the other to the
“Gas Out” port.
Battery
The EGM-4 can be powered by an internal 12V 2.0 Ah lead acid rechargeable battery
providing up to 4 hours continuous use or a 12V NiMH rechargeable battery providing up to 8
hours continuous use.
Powering The EGM-4 With Internal 12V NiMH Battery
There are two ways to power the EGM-4 :-
1. Using the internal 12V NiMH battery:
