29
5.
When prompted by the
‘exhale’
symbol, open
the fine control valve or
regulator.
6.
Allow the gas to flow at 1
litre per minute.
7.
Allow the gas to flow
through the instrument
for the duration of the
test, again monitoring
the rate of flow.
8.
If the final displayed
value is less than 18ppm
or higher than 22ppm,
stop the test and
perform a calibration or
send back to Bedfont®
for a free of charge
calibration, following the
instructions.
