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4. Gas Path Diagram
Response Time
After inserting the probe into the sample gas, there is a
short delay before correct measurement values are dis-
played. This is necessary for the gas to pass through the
sampling system and build up a stable electrochemical reac-
tion at the sensors. This is referred to as response time, and
it usually lasts between 60 and 90 seconds. Before printing
or recording emission results, wait approximately 2 minutes
until the values have stabilized. Minor drifting of a few ppm
can be due to unstable pressure conditions in the exhaust
channel and may be negligible.
Since the CO sensor has an independent gas path with
NOx/SOx filter (see diagram above), the response time will
be slightly longer for CO measurement values.
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