Rosin Ramml Er Fitting

7/24/2019 Rosin Ramml Er Fitting

http://slidepdf.com/reader/full/rosin-ramml-er-fitting 1/1

Purpose:

Fitting a 2-value data set to a Rosin-Rammler formula.

Method:

The general form of the Rosin-Rammler equation is:

 R=e

−  D Dnn

where:  R is the %retained at a size  D and !oth  Dn and n are fitting parameters.

"iven two points  R1 retained at size  D1 and  R2 retained at size  D2 the two fitted parameters ma# !e

determined as follows:

 Dn=e$p

lnln

 R×ln  D2−lnln

 R2×ln  D

lnln

 R

ln

 R2    and n=

lnln

 R

ln D

 Dn

&n'e fitted the %retained  R at an# size  D 'an !e estimated form the general form of the equation:

 R=e

−  D Dnn

and an# size  D that sees a %retained  R 'an !e determined !#:

 D=n

 ln%

 R× Dn

n  or rearranged as  D=[ln

 R × Dn

n]/n

(is'laimer: )*+ ,T &)R &/ R0*1.The author will not a''ept an# responsi!ilit# for loss or damage 'aused !# use of these formulae. The equations have not

 !een tested under stringent 'onditions that allow them to !e 'onsidered ro!ust enough for +ngineering use. People using thismethod must themselves a''ept responsi!ilit# to 'onfirm that results are 'orre't and appli'a!le to the appli'ation !eing

'al'ulated. 

omments wel'ome: ale$.doll3agd'onsulting.'a

CALCULATION COVER SHEET Date: 28-Nov-06

Author:  Alex Doll

Project: General engineering Calc No:

Title: Deriving general fitting equations for Rosin-Rammler 

formula for 2-point case 1