PerkinElmer Photovac 2020 Manual page 161

Technical Description
These recorded data can now be reviewed and edited. Recorded
data can also be printed as either a table or a graph. For each
averaging interval, 2020 prints the minimum of all the minima, the
average of all the readings for the interval and the maximum of all
the maxima.
In PEAK mode, the reading is updated once a second. In the
background, the 2020 datalogger is sampling the concentration and
measuring min, max, and average concentrations for the selected
averaging interval. At the end of every interval, one entry is placed
in the datalogger until the datalogger is full.
The MAX mode displays the maximum signal, with the date and
time that it was recorded. 2020 continues to log data according to
the selected averaging interval, but only the maximum detected
concentration is displayed on the meter display.
In STEL mode, 15 samples are combined to form a 15 minute
average. Once every minute, the oldest of the 15 samples is
replaced with a new one minute average. This moving average
provides a 15 minute average with a one minute update rate so the
meter display will only update once every minute. STEL is set to
zero each time the instrument is turned on.
STEL calculations are always being performed by 2020. You can
display the results of the calculations by selecting STEL as the
Display mode.
TWA mode sums concentrations every second until 8 hours of data
have been accumulated. Once 8 hours of data have been summed,
the accumulation stops.
This sum will only be complete after 8 hours, so the meter displays
the current sum divided by 8 hours. While you are in TWA mode,
the time on the status display will show the number of minutes and
hours of data that TWA has accumulated. When this reaches 8
hours, 2020 stops accumulating data and the TWA is complete.
TWA calculations are always being performed by 2020. You can
display the results of the calculations by selecting TWA as the
Display mode.
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