TSI Instruments SIZER EEPS 3090, Operation And Service Manual

Page: 95 / 185

Software Operation 5-45
Menu Item For a description, see ...
Concentration Scale... Format Menu
Weight Below
View Boundaries Below
Graph Type Below
Grid Lines Below
Color... Format Menu
Font... Format Menu
Copy View Menu
Print File Menu
Print Preview File Menu
Weight
Use the Weight menu to
choose how to “weight” the units that are
displayed.
The options are number, surface, volume, and mass.
Figure 5-39
Weight Menu
The currently selected weighting is marked with a checkmark. Table 5-4
gives a description of each unit.
Table 5-4
Weight Options
View Units Description
Number Number represents the total number of particles per unit
volume of air sampled (i.e., number concentration expressed
as #/cm
3
). Number concentration is the primary measurement
of the Model 3090 EEPS system. The sensor is sensitive to the
number of particles in the aerosol sample as opposed to the
particle mass, color, shape, composition or other characteristic.
The distributions of diameter, surface area, volume or mass
concentrations of the particles are calculated based on the
particle number distribution.
The number concentration, dN, measured by the Model 3090
is the concentration of particles in a given channel. The
normalized concentration dN/dlogDp is the number
concentration of each channel multiplied by the number of
channels per decade (16).
Surface Surface represents the total surface area of the particles per
unit volume of air sampled (i.e., surface area concentration
expressed as nm
2
/cm
3
). The surface area concentration
calculation assumes that all the particles are perfect spheres.
Surface area concentration is calculated by:
dS = dN


D
p
2
,
where D
p
is the geometric midpoint of the particle size channel.