4-4
Model 3090/3090AK Engine Exhaust Particle Sizer
TM
Spectrometer
Pause/Resume
Select
Pause/Resume
to start and stop real-time data display. The button
changes from Pause to Resume each time it is selected. You must select
Pause, before you can use the Cursor menu item, see below.
Concentration Display
While running a sample, you can view particle size data using the CURSOR
(see above). As you move the CURSOR, the information in the
Concentration Display shows the particle size and concentration values for
the CURSOR location.
Particle Data Graph
A histogram of sampled particle size data is presented in the graph window
as normalized concentration dN/dlogDp (#/cc) to allow easy comparison to
other instruments. This particle concentration is normalized to the bin width.
In this case it is calculated by concentration multiplied by 16, the number of
channels per decade. Particle size is presented on a log scale with 32
equally sized bins in the size range of 5.6 to 560 nanometers. Other
weightings, such as particle mass or surface area as well as concentration
that are not normalized can be viewed using the EEPS software.
A yellow curve is shown superimposed on the particle size distribution to
show the RMS lower noise limit of the instrument. For best results, the
concentration should be above the noise curve. In addition, when the
concentration is too high, a red box will appear on the end of each size
channel that has been over-ranged. When this happens, the concentration
should be reduced using additional dilution air into the EEPS spectrometer.
Running the instrument near the upper concentration limit will require more
frequent cleaning of the column. See
Maximum Concentration
and
Minimum Concentration
in the Software chapter for more information.