Casella CEL
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E.TIME WEIGHTED AVERAGE (TWA) PRO ONLY
(Fig. 8) (Only activated when advanced
mode is selected-see configuration chapter)
This mode allows the user to allow a known volume of sample to be taken over a selectable
time period (for example 120L over 8 hours.). In this instance if the pump was set to 2l/min
flow rate, it would only need to sample for 60 minutes over the whole 8 hour sampling
duration. The pump will automatically switch on/off spreading the sample on time over the
whole duration evenly.
Use the UP/DOWN keys to step through the Menu Options until the TWA screen is
displayed.
Press ENTER to continue to the TWA Run screen. Use the UP/DOWN keys to set the total
sampling duration, e. g 8 hours.
Press ENTER to continue to the Exposure time setting. Use the UP/DOWN keys to set the
Exposure Time, e. g 1 hour.
The settings entered will provide 1 hours exposure time evenly spaced over the 8 hours
running time.
Press ENTER to Start.
Figure 8 Time Weighted Average
To exit the program at any time press and hold ENTER. The display will count down 3, 2, 1
and default to the Main Menu.
F. RUN DURATION
(
PRO and PLUS ONLY)
(Fig. 9)
Allows a pre set sampling duration time to be set e.g 6 hours.
Press ENTER to access Run Duration setup screen.
Use the UP/DOWN keys to set run duration in hours and minutes.
Press ENTER again to start the pump. The duration will be counted down and indicate time
remaining. The pump will stop when the duration end time is reached.
Figure 9 Run Duration
