G100 Range
OMG100N1.21
Copyright Geotechnical Instruments (UK) Limited
Page
27
6.2 Gas Measurement Process – Best Practice
Depending on preferences the exact reading procedure can change.
The following method is considered best practice and when followed correctly will allow
quick and consistent readings to be recorded.
1)
When the instrument is first switched on it should be purged with fresh air and
allowed to stabilise for a few minutes.
2)
At this point it is good practice to verify the CO
2
channel. Calibrate only if required.
This option is available via the ‘Calibration’ menu.
The instrument is now ready to take the first reading.
3)
Connect the
sample tube, if relevant (always use the sample filter) from the sample
point to
the inlet
port of the instrument, ensuring the filter is seated correctly.
4)
Press the ‘Pump’ key to draw a sample into the instrument.
Notice the main gas readings start to change. It is recommended to run the pump
until the gas readings have stabilised (approx. 30 seconds) then press the soft-key
‘Store’.
5)
The pump will stop and the operator will be prompted to enter
an
ID
code to identify
the reading. A “reading stored” confirmation message will be displayed briefly before
returning to the ‘Main Read Screen’.
Note: The ID code prompt can be switched on or off. This option is accessed via
the ‘Settings’ menu, then press ‘Key 1 - Prompt for ID: Yes or No’. If the
ID prompt is set to ‘No’ the reading is stored using the default logging ID.
6)
After each reading the instrument should be purged with fresh air.
Gas Measurement Process
(G100 - Best Practice)
(Switch on)
Instrument
warm up
Main Read
Screen
Run a
Clean Air
Purge (no
tubes
attached)
Connect
Sample Tube
from sample
point to inlet
port
Start
Reading Stored
(confirmation
message
displayed)
Enter ID
Code
& press
Enter
END
Press the
‘Store’ key
(pump will
stop)
Disconnect
the Sample
Tube from
the inlet
port
ID Code
prompt field
On/Off?
Take another
reading?
Press the
‘Pump’ key
(draw
sample)
OFF
Default
Logging ID used
ON
Instrument automatically
returns to the
‘Main Read Screen’
NO
YES
Run until
gas readings have
stabilised
Verify gas
Run a
Clean Air
Purge