Hopper Capacity Calculation

The material hopper is an integral part of the feeding system. Typically, it is capable of holding approximately 5–10 kg of material. 

Low level sensors are mounted in the hopper to signal an alarm, shut off the machine or activate a feeding mechanism to deliver more material when the product falls below this level. 

The material hopper should be symmetrical with steep discharge angles to promote mass flow and prevent funnel flow (rat holing) in the granulation. The discharge outlet of the hopper should be as large as possible reaching into the feeder to prevent material bridging. 

On many machines the base of the hopper is equipped with a valve to shut off material flow to the feeder if necessary. Depending on the nature of the granulation, the hopper valve can contribute to material bridging. 

For materials with very poor flow characteristics, a slide valve may be preferable to a butterfly valve.

Hopper Capacity calculation

To calculate the hopper capacity with the following formula

Hopper Capacity calculation= Volume of hopper (in liters) x bulk density of the powder to be filled in hopper

Volume of hopper calculation: 

Fill the hopper with measured volume of water by closing the hopper and report the same in liters. For example the measured volume filled was 10 liters. Then the hopper volume is 10 Ltrs.

Bulk density:

The bulk density of the material is calculated using the following formula : D=M/V 

D= Density of the material (gm/ml)

M= mass of the powder (gm)

V= Volume of the sample occupied (ml) 

Example 

Mass of the powder (M)= 10 gm 

Volume of the sample occupied (V)= 20 ml

D=10gm/20ml = 0.5gm/ml 

Hopper capacity calculation: 

Example: 1

Volume of the hopper : 10 ltrs 

Bulk density of the material : 0.65gm/ml (example)

The Hopper capacity = 10x0.65=6.5 Ltrs 

6.5 ltrs is the hopper capacity 

Example: 2

Volume of the hopper : 20 ltrs 

Bulk density of the material : 0.50gm/ml (example)

The Hopper capacity = 20x0.50=10 Ltrs 

10 ltrs is the hopper capacity