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Chapter 2
Using the Gas Analyzer
Connecting to Other Recorders
Analog signals from the Gas Analyzer are linear and proportional to CO
and O
partial pressures (CO
2
and O
output of 0.05–1 V is equivalent to 5–100% O
2
assumes that you are using a PowerLab and LabChart, the principles of
operation and calibration apply to any meter or recorder that you attach to
the Gas Analyzer.
Using the Gas Analyzer
When fi rst switched on, the Gas Analyzer performs an initial self-test, and it
should then be allowed time to warm up. When used with a PowerLab and
LabChart, the Gas Analyzer has default scaling and units, and so can be used
without further setting up. If required, you can calibrate it yourself using
LabChart (see "Calibration", page 21).
Power-up Test of the Gas Analyzer
Th e Gas Analyzer performs an initial check when it is switched on.
1. Ensure dust caps are removed from both the Sample In and Exhaust
ports of the Gas Analyzer, and that the Exhaust port is clear of
obstruction.
2. Turn on the Gas Analyzer. Its Power indicator should glow blue.
3. Check the internal pump by fl icking the Pump On switch. Its indicator
should glow yellow and the pump may be heard.
Allow at least 10 minutes of operation with the pump on before recording
with the Gas Analyzer. Until it has warmed up, the output from the CO
transducer may be unusable due to a large off set.
Sample Inlet
Th is system is designed for passive sampling only: DO NOT breathe or
blow directly into tubing connected to the inlet port. Connection to a high
pressure source may damage the internal components.
Do not obstruct sample airfl ow as this can damage the internal pump.
It is extremely important that a method of moisture removal is employed
when using the Gas Analyzer because any moisture entering the sample inlet
port can damage the instrument. As a minimum, use Nafi on tubing and an
in-line polypropylene 0.45 μm hydrophobic fi lter (both supplied) to connect
between the subject and the gas sample inlet. Th is has the advantage of being
low-maintenance and reduces the dead-space volume of the sample. Nafi on
output of 0–1 V is equivalent to 0–10% CO
2
2
2
). Although this guide
2
2
19
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