Casella CEL Airborne bacteria sampler User Manual
Page 11
The sampling times can be as low as half to five minutes, if a single rotation
of the turntable is selected at the respective speed and up to several hours if
continuous turntable rotation is used. However to prevent the over heating of
the pump and possible damage, it is strongly recommended that the
maximum sampling times presented in Table 2 are not exceeded at the
appropriate flow rates.
Table 2: Maximum Sampling Times
Number of Slits
Open
Flow Rate
(litres/minute)
Recommended
Maximum
Running Time
1
175
5 hours
2
350
8 hours
3
525
8 hours
4
700
8 hours
When selecting an appropriate sample time, the possibility of the agar drying
should also be taken into account, especially if long sample times are to be
used.
Excessive drying of the collection media may reduce bacterial collection and
inhibit growth.
5.8
Completion of Sampling
If switch G on the sampling unit control panel is switched to single rotation,
the pump and turntable will stop automatically on completion of one
complete rotation of the turntable, after 0.5, 2 or 5 minutes depending on the
turntable rotation speed selected by switch D.
However if switch G is switched to continuous rotation, then sampling needs
to be stopped manually on completion. This is best achieved by switching
switch G back to the single rotation position at the end of the run and
allowing the turntable to complete a final revolution, after which the pump
and turntable will stop automatically by means of a reed switch and magnet
controller.
The time at which sampling was completed should be noted, so that the
duration of sample collection can be calculated. From the sample duration
and set flow rate, the volume of air sampled can be calculated by the
following equation.
Sample volume (m ) =
3
Sample duration (min) x Flow rate (litre/min)
1000
Operation
Page 11 of 16
BACTERIA SAMPLER
User Manual