Solid Coating Pan
Solid pan equipment is also commonly known as conventional pan equipment. In a solid pan, mixing occurs due the angle of inclination and shape of the pan, combined with pan rotation. Traditionally, solid pan equipment was used for sugar coating applications, although it is possible to modify these systems for film coating by addition of appropriate air handling systems and spraying equipment.
Potential Issues of Use for Film Coating Applications
- Solid pan equipment tends to have relatively poor drying capacity
- The inlet drying air only strikes the surface layer of tablets and does not pass through the entire tablet bed, especially in the case of poorly volatile solvents such as water
- Potentially long processing times and overwetting of the product bed (if the process is not optimized)
- The mixing efficiency can be poor, with many dead spots existing within the bed of product being coated
Spray Drying and Waste
- The exhaust system may create a countercurrent of airflow against the inlet airflow causing significant turbulence inside the pan
Solvent and Dust Removal
- Improper balance between inlet and exhaust air can cause dust and solvents to leak into the general coating area, thus creating a potential hazard
Despite the shortcomings of this type of equipment used for film coating, solid pans adapted for a film coating process are still common since this type of equipment requires a lower level of capital investment.