Bulk density of powders and granules

Bulk density calculation for powders and granules play an important role in pharmaceutical industries

Bulk density of powders and granules is the ratio of mass of untapped powder sample to its volume including void spaces.

Formula of bulk density

Following formula is used to calculate the bulk density of powders and granules

d=m/v

d= density

m= mass

v= volume

Why to calculate bulk density

Bulk density of powders and granules is calculated in pharmaceutical industries to calculate the capacity of various equipment used for mixing or kneading of powders like bin blender, double cone blender, rapid mixing granulator and sigma mixer.

Bulk density of powders and granules is calculated for the selection of fill cam for compression machines and for dosing disc of encapsulation machines.

How to calculate bulk density of powder and grandeurs

Bulk density of powders and granules is calculated in following 4 steps

• Weighing
• Volume checking
• Calculation

In first step we weigh a specific quantity of the sample and in step two we add this sample in the measuring cylinder.In 3rd step we note the volume occupied by this sample (don’t shake or tap the cylinder)

In the last step we put values in the formula and calculate the bulk density.

Explanation

Suppose we have two products one is granulated called product A & other is powdered product known as product B.We want to calculate the bulk density of both products.

First we will use the above four steps for product A as

Product A

Suppose we have a specific amount of sample from product A and first of all we will check its weight which will be the ‘m’ of the formula.

We checked the weight of the sample on a calibrated analytical weighing balance and suppose its weight is 30 grams.

Now we will add this 30 grams of the granulated product in a calibrated measuring cylinder and will check the volume occupied by it.This volume will be the ‘v’ of formula.

Suppose its volume is 50 ml.Put values in the following formula to calculate the bulk density for product A.

d=m/v

d= 30/50 = 0.6 gm/ml

Product B

Now we will calculate the bulk density of product B which is a powdered product.

We have a specific amount of sample from product B and will check its weight and volume as mentioned above.

Suppose weight of sample is same as 30 gm and volume occupied is 60 ml so calculate bulk density as

d=m/v

d= 30/60 = 0.5 gm/ml

Conclusion

The bulk density of granulated product A is 0.6 gm/ml and the bulk density of powdered product B is 0.5 gm/ml.