Instrument Operation 4-9
Totalizer Time
Use this option with the Totalizer Mode to select the time period for
accumulating counts. Three options are available; 60 seconds, 60
minutes and Continuous. Sampling stops once the time is
complete. Sampling may be ended manually prior to the end of a
sampling period by selecting STOP.
Pump
The critical flow vacuum pump can be turned on or off by selecting
the Pump option. When idle for long periods of time, the pump
should be turned off to reduce maintenance requirements and
reduce butanol consumption. If the instrument is to be left idle
continuously, it is recommended that a filter be placed on the
aerosol inlet. See below.
Caution
In a dirty environment with high or unknown aerosol concentration, turn the pump
off when possible or provide filter protection at the inlet. This reduces the
likelihood of large fibers clogging the delicate aerosol capillary tube. If the
instrument is used in a monitoring application over long periods of time, an
impactor or cyclone should be used upstream of the CPC to keep large particles
and debris from clogging the capillary tube.
Auto Fill Enable
When the Auto-Fill Enable option is ON, the instrument fills with
butanol automatically when the liquid level indicator in the butanol
reservoir detects a low butanol level condition. A fill bottle with
butanol needs to be connected to the Butanol Fill port to fill the
instrument. Selecting Auto-Fill OFF prevents the fill valve from
opening despite a low butanol level. The Auto-Fill option is turned
on each time the instrument is turned on.
Caution
Auto-Fill is automatically turned on each time the CPC is turned on. Make sure
the CPC is not operated with the reservoir cover plate removed. This will prevent
butanol from spilling out of the instrument as filling takes place.
Analog Out
When the CPC is used as a standalone CPC, the voltage output
from the DMA/Analog Output port at the back panel of the
instrument is proportional (linear or log) to the particle
concentration. There are nine options: OFF, 1E+1, 1E+2, 1E+3,
1E+4, 1E+5, 1E+6, 1E+7, and LOG. The relationship between
voltage output and particle concentration with the options selected
is listed below.
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