To Detect Carbon Monoxide
Carbon Monoxide in Ambient Air
Connect an appropriate probe with a water-block filter and select the Monitor mode.
After warm-up, the display shows the concentration of CO in parts per million (ppm). If the air
is clean (contains no carbon monoxide), the display should read zero. If it does not, use the right
button (“Zero/Off”) to get a new zero in clean air.
Carbon Monoxide in Flue Gas
Connect the flue gas probe, with an attached flue gas filter, to the water-block filter on
the hose and select the Monitor mode. After warm-up, insert the probe into the flue and read the
concentration of CO in parts per million. A flue gas check of CO should take one minute or two.
For every minute of flue gas sampling allow the detector a minute of room air sampling to dry
the filters.
CAUTION:
The filter provided with the flue probe
must
be used to avoid interference by
nitrogen oxides present in combusted gas. A filter is good for about three
months of ordinary use. It should be replaced or refilled when about 90% of
its purple material has changed color to brown, or when it gets clogged or
flooded (see "Accessories and Spare Parts", Flue Gas Filter, Part No. FF-005
and Purple Beads and Spare Retaining Disks, Part No. PR-050).
Note:
The standard flue gas probe and filter are suitable for spot checks lasting a
minute or two. For measurements of CO in flue gas over longer periods use an
Extended Duty Flue Gas Probe and Filter (Part No. FP-012).
WARNING:
Do not touch the flue probe immediately after a measurement. Wait
until it cools. Running the instrument in air helps cool the probe.
"Air-Free" CO Flue Measurements
The EGA-411/412 and 611/612 detectors can display measurements of CO on an "air-
free" basis if this feature is selected (see Part 2). When this selection is made, the measured CO
concentration is referred to air-free flue gas according to:
"Air-Free" PPM CO =
20.9
20.9
measured % O2
(measured ppm CO)
The instrument displays CO concentrations on an air-free basis using the above relation.
The CO reading on the display is labeled by ppm AFCO, i.e. air-free CO. This calculation is
used up to 16.0% Oxygen. Beyond this, measured CO concentrations are displayed without
conversion, i.e., the "air-free" formula is
not
used.
6.