Kidde KN-COPP-3 Owner's Manual page 20

Operation
Peak Level Memory
Although the peak level feature will display levels below
30 PPM, these levels will not result in an alarm no matter how
long the device is exposed to these levels.
The peak level feature is helpful in identifying low level
CO occurrences below 30 PPM. Although the unit will not
automatically display levels below 30 PPM, it will detect
and store these readings in memory. By pressing the peak
level button, concentration levels as low as 11 and up to
999 PPM will be displayed.
Concentrations of CO between 0 and 30 PPM can often occur
in normal, everyday conditions. Concentrations of CO below
30 PPM may be an indication of a transient condition that
may appear today and never reappear. Just a few examples
of conditions and/or sources that may cause low level
readings are heavy automobile traffic, a running vehicle in
an attached garage, an appliance that emits CO when starting
up, a fire in a fireplace or charcoal in a nearby barbecue.
A temperature inversion can trap CO generated by traffic
and other fuel burning appliances causing low level
readings of CO.
Normally, the digital display will read "0" and under certain
conditions you may notice levels of 30 or more for short
periods of time, by using the Peak level memory feature on
the Kidde CO alarm you can view concentrations of CO
between 11 and 30 PPM. Use the low-level concentrations
shown in memory as a tool in identifying the source of the
CO. It may be helpful to purchase additional Kidde CO
Alarms to place in different locations throughout your house
to isolate the CO source. Monitor the CO concentrations
shown in the peak level memory to see if readings occur in
certain areas at certain times of the day, or near a particular
appliance.
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