Page 34
AMBIENT CO2 + CO TEST
Measuring Ambient CO
2
.
CO
2
is a very difficult gas to measure because there are many sources generating it.
Whilst 'zeroing' in 'fresh air' is adequate when measuring flue gases where the CO
2
concentration ranges from 5% (50,000ppm) to 12% (120,000ppm), or so, when
measuring at ambient levels a more consistent zero is recommended. This is because
'fresh air' is often not fresh enough and is not constant. Car exhaust fumes, boiler
flues and humans and animal breathing (40,000 ppm in breath) all contribute to
variable levels of CO
2
in 'fresh air'.
If ambient CO
2
readings are taken immediately after flue CO2 readings have
been taken it may take a few minutes for the system to be completely purged of
CO2.
For accurate ambient measurements the KANE457 should always be zeroed using a
'ZEROCAL' capsule. This capsule contains a chemical that absorbs CO
2
and totally
removes it from the gas stream. Please note that these chemicals don't last forever
and the capsule must be replace at least annually. The colour of the chemicals
change as more CO
2
is absorbed
TAKING AMBIENT READINGS
Rotate the dial to AMB CO2 + CO
AMBIENT CO2 + CO DISPLAY
COp 0
→
Real time CO reading (ppm).
CO
2
p 1234
→
Real time CO
2
reading (ppm).
COx 00
→
Maximum CO reading (ppm)
CO
2
x 2345
→
Maximum CO
2
reading (ppm)
These reading can be printed by quickly pressing the PRINT/SEND key or can be
stored in memory by pressing the PRINT/SEND key until the analyser beeps and a log
number appears on the top line of the display
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