Dräger Multi-PID 2, User Manual

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39
Using the Multi-PID 2
Short-Term Exposure Limit (STEL) Mode
The Short-Term Exposure Limit (STEL) mode displays the concentra-
tion as a 15-minute moving average. The Multi-PID 2 maintains
15 samples, each representing a one-minute averaging interval.
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 of the last 15 minutes with a one-minute update rate. Since
the average is calculated using 15 one-minute averages, the meter
display will only update once every minute.
STEL is set to zero each time the instrument is turned on. Since STEL
is a 15-minute moving average, there is no need to clear or reset the
STEL.
STEL calculations are always being performed by the Multi-PID 2. You
can display the results of the calculations by selecting Interval Mode.
Time-Weighted Average (TWA) Mode
The TWA accumulator sums concentrations every second until 8
hours of data have been combined. If this value exceeds the TWA
alarm setting, a TWA alarm is generated. The TWA is not calculated
using a moving average. Once 8 hours of data have been summed,
the accumulation stops. In order to reset the TWA accumulator, press
the
" clear " key, then select » TWA « using the "
l
" key, then press
" clear " .
This sum will only be complete after 8 hours, so the meter displays
the current sum divided by 8 hours.
TWA calculations are always being performed by the Multi-PID 2. You
can display the results of the calculations by selecting Interval mode.
REAL Mode
The REAL mode displays the current detected concentration. The rea-
ding is updated once a second. In the background, the Multi-PID 2
datalogger is sampling the concentration and measuring minimum,
maximum, and average concentrations for the selected averaging
interval. At the end of every interval, one entry is placed in the datalog-
ger until the datalogger is full.
In order to reset the REAL reading, press the " clear " key then select
» REAL « using the "
l
" key then press " clear " .