Heath Consultants GT Series - Manual (Page 81)

7-5
CO (CARBON MONOXIDE) MODE
7.4.3 Air-Free CO
Air-free CO is the CO reading modified by the O
2
reading,
therefore this measurement will only be available when
an O
2
sensor is fitted. The purpose is to determine whether
or not the emissions from an un-ventilated appliance,
principally an oven or a stove / cooker, are safe.
This is the CO reading modified by the O
2
reading
(only applicable if O
2
sensor is fitted).
CO Air-free = (20.9 x CO) / ( 20.9 – O
2
).
The typical display for this mode is shown in Fig. 7.5:
Fig. 7.5 Air-Free CO
A sample is considered invalid until the Oxygen (O
2
)
concentration is below 19% Vol.
Changes to Fig 7.6 when valid sample is taken
Fig. 7.6 Valid Sample