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OMGEM5KN4.7.1
9.0
Calibration
9.1 Calibration introduction
The GEM5000 gas analyzer is carefully calibrated at manufacture and when returned for
service. However, it is sometimes desirable to be able to carry out a calibration process
between services.
This section outlines the correct procedures to enable the site engineer to field calibrate
the gas analyzer.
Note:
This does not replace the factory service and calibration. If this calibration is
completed incorrectly it may decrease the accuracy of the gas analyzer.
CH
CO
and O
can be measured by GEM5000 gas analyzer as standard; these channels
4,
2
2
can be user calibrated. The analyzers have other gas channel options that are specified at
manufacture; these too can be calibrated. This section will describe in detail how to
calibrate the three standard gas channels plus the CO channel.
The GEM5000 instrument can have a H
that H
is used in the calibration process and is also set out within this section.
2
For the other gas channel options contact QED for advice.
Two important terms that are used within this section are 'Zero' and 'Span'.
Zero:
The point at which the gas analyzer is calibrated when there is none of the target
gases present.
Span:
The point at which the gas analyzer is calibrated when a known quantity of the
target gas is present.
9.2 Frequency of calibration – best practice
The GEM5000 gas analyzers can be checked against a known concentration of gas, to give
confidence that the analyzer is operating as expected at the time and conditions in which it
is being used.
It is recommended that the instrument is regularly serviced and calibrated by QED in
accordance with the due date on the instrument.
When defining the frequency of user calibration, the following are factors to be considered:
The frequency of use of the analyzer. (daily?/monthly?)
The level of confidence and accuracy required for readings to be taken.
Historical user calibration data.
Site specific requirements or conditions.
Historical understanding of expected readings on site.
Zeroing of the gas analyzer should be undertaken at the start of each day's monitoring.
Use historical data to drive your frequency of calibration.
If there is no historical data a good starting point for a daily monitoring round is
performing a calibration once every week or every other week.
The results of the calibrations will need to be recorded to monitor over time whether the
frequency of calibration needs to be increased or decreased relative to the confidence
required.
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GEM5000 Gas Analyzer
compensated CO channel. This option requires
2
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