Malvern Instruments Spraytec, User Manual

Page: 156 / 221

The dialogue allows the user to name the external instrument and the units
it uses. These will be printed
.
Sr [x1] – raw scattering on detector x1 .
.
Sc [x1] – corrected scattering on detector x1 .
.
BI [x1] – background intensity on detector x1 .
.
-X- – when selected, this shows whether a record coincides with a trigger.
It writes a 1 to the result if a trigger is used or 0 if no trigger is used. For
these records the text “--X--” appears in the header line of the record views.
Rosin-Rammler parameters
The Rosin-Rammler equation is a two parameter fit applied to a size distribution
that has the shape of a skewed distribution with a tail of fines. It has traditionally
been used in the cement and coal industries, though is less commonly used now.
Its parameters are provided for historical comparisons. It uses this equation to fit
the size distribution:
F
d
x
N
= -ìí
î
ü
ý
þ
ì
í
ï
îï
ü
ý
ï
þï
exp
The Spraytec calculation fits a straight line to this data and obtains the two
parameters used in the fit:
.
Drr – Rosin-Rammler central size point.
.
Nrr – N the distribution width (gradient of the fit).
Log-Normal parameters
When the Log-Normal two parameter distribution model is used, the analysis
reports:
.
Drr – Geometric Mean.
.
Nrr – Geometric Deviation for this distribution.
The Log-Normal equation is:
( )
( )
( ) ( )
( )
( )
( )
F d
n
d x
n
= -
-
æ
è
ç
çç
ö
ø
÷
÷÷
1
2
2
2
2
p
ln
exp
ln ln
ln
Where F(d) is the relative frequency at size d and x and n are the characteristic size
and width of the distribution. ln is the natural logarithm. The cumulative
distribution is the integral of F(d) .
C H A P T E R 1 0
S p r a y t e c
P a g e 1 0 . 4
M A N 0 3 6 8