Flow Properties of Powder: Industrial Pharmacy 1st

Easy to Pharmacy 5th Sem: Industrial Pharmacy 1st

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

2. Jens Martensson
“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. Jens Martensson
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. Jens Martensson
•“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. Jens Martensson
•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
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6. Jens Martensson
“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. Jens Martensson
% Carr’s Index = (Tapped density –Bulk Density) / Tapped Density x 100
% Carr’s Index = ( T
D –B
D) / T
D * 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. Jens Martensson
•“Hausner’s is the ratio of tapped density to bulk density.”
❑Housner’s Ratio
8
Housner’s ratio = Tapped Ratio / Bulk Ratio
H.R = T
D/B
D
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