INFICON 2020ComboPRO Portable Photoionization Detector - Manual (Page 61)

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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, the 2020ComboPRO stops accumulating data and the TWA is
complete.
Interval mode logs readings at user-selected intervals of 1 second to 999 seconds.
Figure 17. Interval time adjustment
Interval simultaneously displays the STEL, TWA, and PEAK reading along with the
instantaneous reading. The 2020ComboPRO’s datalogger can store up to 200 hours
of 1 minute sample entries. The interval you select will determine the period of
operation. At the end of the period, the datalogger will be full and you will see the
“Data Log Full” status.
Table 2. Averaging Intervals and Period
STEL, TWA, and PEAK Operation
Averaging
Interval
(example)
Hours of Operation to
Fill the Datalogger
15 s 50
1 m 200
2 m 400
5 m 1000
15 m 3000
The 2020ComboPRO’s display can show four values in Interval mode: STEL,
TWA, and PEAK, plus the instantaneous reading.