Biogas Operating Manual
BMUK0001 / Issue 1
Geotechnical Instruments (UK) Ltd
Page 15
5.5 Gas
Analyser
To achieve the processes set out below choose “Field Calibration” from the Biogas menu.
The first screen to appear (“Check Calibration”) provides the option of checking the gas channels
against known calibration gases before proceeding to re-calibration. Ensure the unit is stabilised at its
working temperature before performing any of the calibration operations.
Readings on the line “a” are the current readings for the channels listed. The figures displayed in line
“b” are the span targets i.e. the concentrations of the calibration gases to be used.
Please note: Depending on the configuration certain gas channels may not be active and will be shown
as “N/A”.
Step 1: Enter Target Concentrations
DO NOT CONNECT CALIBRATION GAS YET.
Enter the certified concentrations of your calibration gases. For two-gas mixtures that contain 0.0% O2,
enter the certified O2 value at 20.9%. For three-gas mixtures with an O2 component enter the O2
certified concentration.
•
Press
to Edit target concentrations.
•
Select CH
4
from the menu using
and enter the certified CH
4
concentration. Then press
.
•
Press
to Edit target concentrations.
•
Select CO
2
from the menu using
and enter the certified CO
2
concentration. Then press
.
•
Press
to Edit target concentrations.
•
Select O
2
from the menu using
and enter the certified CO
2
concentration or 20.9% for air
calibration. Then press
.
Step 2: Zero CH4 and CO2 channels
•
Press
allow the pump to run for approximately two minutes or until reading stabilises; this
purges the unit of gas.
•
Press
to switch off the pump.
•
Press
to select “Calibration Menu”.
