UEi Test Instruments KM940 - Manual (Page 13)

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4.4 Sampling the Flue Gas
Once the automatic calibration procedure has been completed and the specific fuel has been
selected (See SELECT menu) the probe can be inserted into the desired sampling point.
It is recommended that the sampling point be located at least two flue diameters downstream
of any bend and that the probe tip is in the centre of the flue. With balanced flues and other
domestic units the probe should be positioned far enough into the flue so that no air can ‘back
flush’ into the probe. This will be indicated by a low oxygen reading and/or a low ‘Poison
Index’ reading.
The probe depth stop cone provided with the instrument allows the probe to be used in holes
whose diameters range from 8 mm to 21 mm (
5 /
16
to 13 /
16
inch).
The standard probe is rated at 650
°C. Temperatures of up to 1100°C (2012°F) can be
accommodated using an optional high temperature probe.
TIP To conserve battery power, switch off the pump when you are not taking a
measurement. Use the key to turn ON and OFF the pump.
4.5 Taking a Pressure Reading
With the optional pressure module fitted a flue draught measurement can be made at any time.
Connect the standard probe to the pressure sensor inlet and the probe in the flue.
The pressure reading will be displayed :-
CO/CO2 R . . 0.0001
P INDEX % . . . 0.01
XAIR % . . . 0.0
Prs mbar 0.00
To perform a combustion test and display draught pressure at the same time a special probe is
required. Contact Kane International or Authorised Distributor for details.