Malvern Instruments Spraytec, User Manual

Page: 155 / 221

.
Trans – the transmission %, described in Chapter 2.
.
Obs – a % measure of the amount of laser light obscured by the spray.
When no spray is present the obscuration is 0%. The value increases as the
spray concentration increases. It is equivalent to 100-
Trans , for example
95% transmission
º
5% obscuration.
.
Cv
– the volume concentration. This is calculated in volume (%) from the
Beer-Lambert law and is expressed in Parts Per Million (PPM).
.
SSA – Specific Surface Area, the total area of the particles divided by the to-
tal weight. If using this value, it is important that the density of the spray is
defined (on the first
Analysis SOP dialogue). This figure is a mathematical
calculation based on the assumption that the particles are both spherical and
non-porous.
.
%>x1 , %<x1 – percentages above or below a particle size.
.
x1 < %< x2 – the percentage between two particle sizes.
.
[Dv(x1) - Dv(x2)]/Dv50 – this measures the width of the distribution.
The final parameter is always the Dv(50) and x1 should be greater than x2 .
When x1 =90 and x2 =10 the value is called the span . The narrower the
distribution, the smaller the span becomes. The span is calculated as:
Dv(90)
Dv(50)
-
Dv ( ) 10
.
Dv(x1)/Dv(x2) – this is the ratio between two percentiles.
.
ASD – Arithmetic Standard Deviation, calculated as:
( )
[ ]
ASD V d Dv
i i
= -
å
( ) 50
2
Where: Vi=relative volume of band i and di=size of band i.
.
GSD – Geometric Standard Deviation, calculated as:
( )
[ ]
GSD V d Dv
i i
= -
å
exp ln( ) ln( ( )) 50
2
Where: Vi= relative volume of band i and di=size of band i.
.
Drr – the Rosin-Rammler central size point (see below for details).
.
Nrr
– the Rosin-Rammler distribution width (see below for details).
.
Aux x1 – the Spraytec interface unit has a number of auxiliary ports. These
can be used to acquire a signal from other instruments. To view the signal
in the Size History view, select this variable type and specify the
x1 value,
the name of the instrument and the units in which the signal is displayed.
The
x1 value is the number of the auxiliary port the instrument is con-
nected to.
C H A P T E R 1 0
S p r a y t e c
P a g e 1 0 . 3