CareFusion Smoke Check Manuel D'utilisation page 50

The subject may now seal their lips around the mouthpiece and exhale
slowly and fully if they cannot hold their breath any longer. However,
more accurate results will be obtained if they hold their breath until
the buzzer sounds and the display changes to:
The CO reading will rise to a plateau over the course of several
seconds. The final value will be held until the unit is turned off and will
be displayed in one of the four ranges:
0 - 6 ppm with green indicator
7 - 10 ppm with amber indicator
11 - 20 ppm with red indicator
20+ ppm with flashing red indicator and alarm
Important note:
Before repeating a measurement the unit must be turned off,
and the mouthpiece and adapter removed for at least 1 minute.
This is to allow re-equilibration with ambient air and to dry the
surface of the sensor. Visually inspect that all moisture has
evaporated from the surface of the sensor before reuse.
If the unit is switched on again too quickly after use there may
be a response to residual expired carbon monoxide from the
previous test.
Blow
0-6 ppm
48