Side-Vented Coating Pan
One of the best methods of achieving the basic requirements of the film coating process is to use a purpose-designed, side-vented coating pan.
Side-Vented Coating Pan Advantages:
- Mixing — achieved by pan rotation and appropriate baffle design
- Very efficient drying and short coating times — the air stream flows in one direction through the perforated pan wall, through the tablet bed, and straight into the exhaust duct
- Effective removal of solvent vapor (plus dust and used air) — due to the perforated pan and straight line airflow
In order to achieve an optimum process in a side-vented coating pan, it is important to fully cover the exhaust plenum with the product to be coated.
One method of allowing for variations in pan load is to fit a variable exhaust shoe which can be adjusted so that the plenum is always covered, even at lower than normal pan loads. Some modern machines come equipped with such an adjustable exhaust duct.* An example is shown in the photograph below:
*It is important to remember to restore the exhaust area to full size when returning to the normal pan load.
It is often required to coat significantly different batch sizes during product development and scale-up. In these situations the use of a multi-pan approach will enable the most appropriate pan size for the tablet load being processed to be selected. Multi-pan, side-vented coating machines are now available from many well known coating equipment manufacturers.