Operation
EGM-4 Operator's Manual – Version 4.19
- 32 -
Changing the Zero Time
Press key 1 (1ZERO) and then key 2 to change the Auto-Zero time.
Zero time is the interval between Zeros in minutes when ZERO TYPE is set to Auto. If the
displayed time is correct, simply press the Y key. If you want to change the ZERO TIME,
press key N and enter a value up to a maximum of 40.
Note, for values less than 10,
leading zeros are required (i.e. 05 for 5 minutes).
The new value will be updated on the
display. To accept, press the Y key.
3PMP
Press 3PMP to enable/disable the internal sampling pump. By default, the sample pump is
on.
If required, the internal pump can be turned off by pressing the N key.
Static Sampling with the EGM-4
If static sampling is selected, the user can inject samples directly into the sample cell through
the port labelled “Gas Out” rather than having the sample pumped through it. This is normally
done using a syringe with 1/8” tubing on the end which can easily fit over the “Gas Out” port
on the EGM-4. For static measurements injected directly into the “Gas Out” port, we
recommend a minimum volume of 5 ml. During the course of measurements, a warning is
given 2 minutes and 1 minute prior to the instrument performing a ZERO followed by the
pump turning on for a ZERO. On completion of the Analyzer ZERO, the pump will again
switch off. By default, the EGM-4 is set to dynamic sampling with the pump on at all times.
The general procedure for static measurements is as follows:
1. From the Main Menu, select 2SET, 3PMP.
2. With the “SAMPLE PUMP ON” message displayed, press key N to change to
“STATIC SAMPLING”.
3. Press key Y to accept and then press key Y again to return to the Main Menu.
4. Press 1REC. The instrument will now perform a ZERO. Once the ZERO is
complete, the pump will turn off.
5. Inject your sample (minimum of 5ml) directly into the Gas Out port. We recommend a
slow, steady injection rate of approximately 6 ml/second. Initially, the CO
2
concentration will be higher (due to pressure) and then will drop to the actual
concentration and should remain stable. Once the reading stabilizes, press the Y/R
key to record the values. Remove the syringe from the “Gas Out” port to allow the
system to flush properly.
6. After recording, press the 0/Z key to flush the sample cell and to allow the instrument
to perform a ZERO before injecting your next sample.
4AV
The outputs from the CO
2
sensors
are normally
subjected to an averaging process. This
consists of differencing the current reading and the stored average reading (both raw data). If
the difference exceeds the average limit, then the current
reading
replaces the average.
ZEROTIME = 40
Y=OK N=NEW VAL
SAMPLE PUMP ON
Y/OK N/CHANGE
STATIC SAMPLING
Y/OK N/CHANGE
