Geotech G200 - Span Channels; Last Field Calibration; Calibration Record

Page 42 of 61
Operating Manual
www.geotechuk.com
OMG200N Iss.04
© QED Environmental Systems Ltd.
G 2 00 R A N G E
Note: If the calibration failed then purge and try again or select a different air source.
Note: If using G210 – very high concentrations of CO2 may take up to 30 minutes to purge
completely. O2 is not zeroed.
Span Channels
It is recommended that the instrument is spanned to target the desired reading range (refer to
section Recommended Gases for Calibration of this manual for more information); ideally this should
not be a low level close to zero.
If not already preset, enter the correct span target, i.e. certified concentration of your
calibration gas. Press ‘Key 1’ and enter the new value. Then attach the gas and open regulator
valve to allow the gas to flow.
Press the ‘Start’ key and wait for the reading to stabilise. This can take a couple of minutes.
Press the ‘Pump’ key to draw sample gas.
Once a stable reading is shown press the soft-key ‘Accept’. A successful span calibration
message will then be displayed. Press the soft-key ‘Accept’ again to confirm the calibration and
‘Store’ the new user span. Alternatively, press soft-key ‘Reject’ to exit without change.
Note: If the calibration failed then try again using a longer purge time or different target gas.
Last Field Calibration
This data can be found in the ‘Information’ screen accessed via the ‘Utilities’ menu. This option
displays the date that the last field calibration was performed on the instrument.
Calibration Record
The G200 instruments have the facility to log user calibrations via the ‘Event Log’. This can be used as
an aid in ensuring that gas measurements are valid and accurate.
During calibration the instrument will record the following in the event log. For each entry the time
and date will be stored.
Event
Data Recorded
Successful user zero for selected gas
Type (N
2
or Air) and Readings before and after
Successful user span for selected gas
Target Value, Readings before and after
Successful user span for selected gas
Target Value, Readings before and after
Failed user zero for selected gas
Type (N
2
or Air) and Reading
Failed user span for selected gas
Target Value, Gas Reading
Failed user span for selected gas
Target Value, Gas Reading
Return to factory settings
Note: If the calibration failed, then try again using a longer purge time or different target gas. This
event log can only be downloaded and viewed via the optional Analyser Data Manager software. It
cannot be viewed on the analyser screen.