E-1
A P P E N D I X E
A n a l o g O u t p u t
Engine Exhaust Particle Sizer
™ (EEPS™) Model 3090 spectrometers
(manufactured approximately August 2006 and later) come standard with
four configurable analog outputs. These analog outputs offer users a
convenient way to incorporate particle emission measurements into the
dynamometer host data collection system. Configuration of the analog
output parameters is performed using the Analog Out tab of the Properties
window in the EEPS software.
Each analog output operates independently and is configurable for the size
range, weighting, and concentration range. The size range for each output
can be set for the full measurement range of the instrument (i.e., 5.624 to
562.3 nm), or any other size range, including down to less than the width of
a single channel (one sixteenth of a decade). An example where a user
might be interested to set a defined size range would be to output
measurements of either the accumulation mode particles (i.e., soot) or the
nucleation mode particles (SOF). Spin buttons in the software make it easy
to select standard EEPS channel boundaries, or specific sizes can be
entered within the size range of the instrument. The analog outputs can
also be configured for linear or log outputs, as well as concentration (dN)
or normalized concentration (dN/dlogDp).
The analog outputs have standard calculations for number concentration,
surface area concentration, volume concentration and mass concentration
(when a density value is entered) as shown in the table below. All standard
calculations for surface area, volume and mass assume spherical particles.
Since engine exhaust particles can be non-spherical there is a custom
setting that allows a user to input any value for the weighting constant,
power of diameter and density.
Weighting
Weighting Constant
Power of D (diameter)
Density
Units
Number
1
Zero
Not Applicable
#/cm
3
Surface Area
Squared
Not Applicable
nm
2
/cm
3
Volume
/6
Cubed
Not Applicable
nm
3
/cm
3
Mass
/6
Cubed
Selectable
µg/m
3
Custom
Selectable
Selectable
Selectable
µg/m
3
