Fitting a pitot tube to a sample point:
7) To take flow readings using a pitot tube, please follow the instructions displayed on the front of the
instrument. The user will be prompted to complete each step and should follow the instructions on
screen.
How to use an H2S filter (optional)
Cross gas effects on chemical cells
Measurements of CO are important in landfill management. The GEM5000 analyser incorporates an improved
CO measurement. Measurements of CO can be affected by two other gases that can be found in landfill gas –
hydrogen and hydrogen sulphide.
To reduce the effect of hydrogen, the GEM5000 analyser uses a technique that is hydrogen compensated.
Hydrogen compensation is achievable up to a level of around 2000ppm. Above this level the CO reading will not
be compensated for.
In order to assist the operator the GEM5000 instrument also indicates the level of hydrogen present as low,
medium or high. If a high hydrogen reading is present then the CO reading may be affected.
The effect of hydrogen sulphide is eliminated by the use of a H2S filter.
CO measurement
The CO measurement is sensitive to hydrogen sulphide. The presence of hydrogen sulphide can cause the CO
reading to elevate (not to be the true value due to the interfering gas). If the presence of hydrogen sulphide is
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