Tablet coating is the process where we apply excipients over tablets in the form of a layer & this process is carried out in a coating pan.
The excipients can’t be applied in dry form, so we have to prepare a solution or suspension of tablet coating materials in a suitable solvent.
The suspension is sprinkled over the tablets, which are in motion.
The solvent is evaporated by the introduction of hot air, and a layer or solid coating materials is deposited over the tablets.
In conventional coating pans, the solution was manually filled into the small reservoir, which was fitted over the spray gun and from this reservoir it was sprayed over the tablets after atomization.
With the advancement of the coating process, the perforated pans are used with multiple spray guns & supply of coating suspension to these guns is also automated.
A pump used to provide coating suspension to the spray guns is known as a peristaltic pump.
What is a Peristaltic Pump
A pump installed to provide coating solution/suspension from the reservoir of suspension to the spray guns is known as a peristaltic pump.
It is named for the natural process of peristalsis where food is transferred by the peristaltic movement of the digestive tract.
How a Peristaltic Pump Works?
Peristaltic pump works on the principle of peristalsis where a pressure is applied over the flexible tubes by the rollers to create a temporary seal and pushes the suspension forward.
Due to the movement of rollers, the tubes come back to their original stage, which results in the creation of a vacuum. This vacuum draws more suspension, and this process goes on in a circular motion, which ensures a continuous supply of coating suspension to the spray guns.
Explanation
The suspension delivery pipe is passed through the rollers.
The peristaltic pump may be single-head or multi-head, depending on the model of tablet coater, i.e if each spray gun has a separate supply line, then the peristaltic pump will be multi-head.
One side of the silicon tubing is dipped into the coating suspension & after passing through the pump head, the other side is connected to the spray gun.
When the pump is on, the specific volume is delivered to the spray guns. The amount of solution can be increased or decreased by controlling the rpm of the pump head.
Benefits of a peristaltic pump
- The delivery of coating suspension through a peristaltic pump ensures a uniform supply of suspension to each spray gun.
- There is a prevention of contamination as the solution does not come in contact with the pump.
- A peristaltic pump has the ability to supply solutions with different viscosities.
- A peristaltic pump gives control over the delivered volume as per requirement.
- Peristaltic pump results in the automation of suspension delivery and is GMP compliant.
Drawbacks of the peristaltic pump
The only drawback of the peristaltic pump is the wear of silicone tubings, so we have to replace the tubings after specific intervals.
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