OMGEMN1.41
GEM2000 Range Gas Analysers
Page 76
Copyright 2009 Geotechnical Instruments (UK) Limited
Under and Over Range Codes
If a reading is under range (i.e. below zero) it will be displayed with ‘less than’ chevrons
(
<<
). This can occur if a channel has been incorrectly calibrated.
If a reading is over range (i.e. above the maximum allowed reading) it will be displayed
with ‘more than’ chevrons (
>>
).
A number displayed as an asterisk (
*
) indicates an error and a hash (
#
) indicates where
no data is available.
9.2 User Calibration Trouble Shooting
Error
Remedy
User zero failed
A possible reason for this is because the gas analyser is trying to
zero to a level which is outside the pre-determined range set
when the unit was first calibrated at the factory. To rectify this,
first ensure the unit contains absolutely none of the gas which is
being zeroed. For all but O
2
(which requires O
2
free gas) and
CO
2
run the pump to purge with fresh air and repeat zeroing
process.
If it will not zero, then refer to the instructions given in the
‘Factory Settings’ section.
If the gas analyser continues to fail in zeroing then the unit must
be returned to Geotech (UK) Limited for investigation.
Calibration failed
Check the span is set to the correct value, if not, correct and
retry spanning the channel.
Repeat the entire procedure, including zeroing the channel and
then calibrate the span. Ensure the reading is stable before
spanning the channel.
This message may also appear if attempting to use the ‘Span
Multi-Gas’ option when not using a gas containing concentrations
of CH
4
, CO
2
and O
2.
