Casella CEL Apex personal sampling pumps - Manual (Page 18)

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must be sampled for a long period. The duration of the run can be set from the instrument keypad.
On Apex Pro, the duration can also be set via Pump Manager software.
1.
Switch Program Mode ON and accept it as described in Section 2.4.
The instrument reverts to Hold Mode.
2. Press or several times until DUR blinks on the display.
3. Press to select it.
The programmed duration blinks to indicate it can be changed by and .
Run durations between 3 minute and 1 hour can be set in 1-minute steps and durations
between 1 and 25 hours in 10-minute steps.
4. Make changes to the duration as necessary.
5. Press to accept the duration and start sampling.
In addition to the symbol, the display shows PROG. to indicate that a program is active.
While the program is running, the display cycles through current run time, volume sampled, air
temperature, and programmed duration.
Once completed, the pump will switch OFF and the display show and a PROGEnd message.
6. Press any key to return the pump to Hold Mode.
3.6 Locking the Keypad
The keypad may be partially or fully locked to prevent unauthorised tampering with the instrument settings.
The keypad can also be locked in the Program Modes.
1. Press three times within 2 seconds to activate Partial Lock Mode.
The symbol is displayed, the counters and flow rate cannot be changed, so the only keypad
options available are:
Start/stop sampling,
Switch the pump OFF,
Unlock Partial Lock (Press three times within 2 seconds),
Select full lock.
2. While the pump is running (sampling), press three times again
within 2 seconds to activate Full Lock Mode.
The symbol is displayed, the pump cannot be switched OFF and the only available keypad
option is to release Full Lock.
3. Press three times within 2 seconds while in Full Lock Mode to fully release the control keys.
(Similarly, while the pump is not running (sampling) in Partial Lock Mode, press three times
within 2 seconds to fully release the control keys.)
4.
ADDITIONAL SAMPLING MODES
AVAILABLE ONLY TO THE APEX PRO
AND APEX PRO I.S.
These modes are available when Program Mode on an Apex Pro or Apex Pro I.S. has been enabled from
within Configuration Mode as described in Section 2.4.
4.1 TWA Sampling Mode
Time weighted average (TWA) mode allows the pump to sample for a fixed percentage of a specified run
time. The instrument calculates the required ON/OFF cycle automatically to spread the total sample time
evenly over the entire run time as shown in Figure 10.
This feature is useful when the requirement is to sample a stated volume of air over the course of a long
period.