1.
FLOW
PROPERTIES
OF POWDER
RAHUL PAL
B.PHARM 5th SEM
(Industrial Pharmacy 1st )

2.
JensMartensson
“Powders may be free flowing or sticky.”
Flowabilty of powder & chemical stability depends on the habit & internal structure of
a drug.
❖ Habit - Description of the outer appearance of a crystal.
❖ Internal Structure – Mainly depends on the environment for growing crystals.
• Powder flow property can affected by the change in particle size, shape & density.
The flow property depends upon following –
❑ Force of Friction – Generated by two surfaces that contacts & slide against
each other, angle & position of object mainly affected.
❑ Cohesion Force – Between one particle to another.
Example – Caking tendencies within a bag after shipping or storage time or
talcum powder.
❑ Powder Flow Properties
2

3.
JensMartensson
Test to evaluate the flowability of a powder –
❑ Determination of Powder Flow Properties
3
1
➢Angle of Repose
2
➢Carr’s Compressibility
Index
3
➢Hausner’s Ratio

4.
JensMartensson
• “A technique for estimating the flow properties of powder determined
by allowing a powder to flow through a funnel & fall freely on to a
surface.”
Other methods to determinding the angle of repose-
 Static angle of repose.
 Fixed funnel method.
 Fixed cone method.
 Kinetic & dynamic method.
 Rotating cylinder method.
❑ Angle of Repose
4

5.
JensMartensson
• The height & diameter of resulting are measured –
Where ,
h = Height or powder cone (pile).
r = Radius of circle.
Continue…
5
Angle of repose
(Degree)
Types of flow
<25 Excellent
25-30 Good
30-40 Passable
>40 Very poor
𝜽 = tan-1
𝒉
𝒓

6.
JensMartensson
“One hundred time of the ratio of the different tapped density & bulk
density to the tapped density.”
➢Bulk Density = Ratio of weight to volume of sample
➢Tapped Density = Ratio of weight of sample to volume after trapping
a measuring a cylinder 500 times from a two inches height.
• It may be also known as “Percentage Compressibility.”
❑ Carr’s Compressibility Index
6

7.
JensMartensson
% Carr’s Index = (Tapped density – Bulk Density) /Tapped Density x 100
% Carr’s Index = (TD – BD) /TD * 100
7
%Carrs Index Type of Flow
< or =10 Excellent
11-15 Good
16-20 Fair
21-25 Passable
26-31 Poor
32-37 Very poor

8.
JensMartensson
• “Hausner’s is the ratio of tapped density to bulk density.”
❑ Housner’s Ratio
8
Housner’s ratio =Tapped Ratio / Bulk Ratio
H.R =TD/BD
Hausner’s Ratio Flow Properties
1-1.11 Excellent
1.12-1.18 Good
1.19-1.25 Fair
1.26-1.34 Passable
1.35-1.45 Poor
1.46-1.59 Very poor

9.
Thank
You