In the pharmaceutical industry flat jet two-substance nozzles are used in coating drums for the coating of pharmaceutical products. If possible, the coating process should not be interrupted for economical reasons. In addition to the geometry of the coater, the drying air and the spraying liquid, the nozzles play a particularly important role in this process.

A new nozzle with an anti-bearding cap (ABC-Technology®) meets the requirement for operating security and improved handling during coating. During coating the HPMC and Eudragit coatings are finely atomised, formed into a jet and channelled towards the tablet bed. The movement of materials in the coater means that tablets can repeatedly fall evenly through the nozzle spray. The small coating drops ideally meet on the tablet surface, blend with the neighbouring drops, the liquid evaporates and a closed film is formed with the required properties.

Indispensable: a jet made up of even drops

The user has very specific requirements for the atomisation nozzles: they must have a hygienic design (they must contain a low number of corners, dead spaces, threads, clean passages and surfaces) as well as pneumatic notching up / targeting of the liquid with the cleaning needle. Product build-up or bearding in the front area of the nozzle may have an impact on the spray or may even block the nozzle. The spray with small, evenly reproducible drop size should be able to be set flexibly to a particular drop size in order to avoid spray drying of the drops before they reach the tablet cores and, on the other hand, to prevent excess moisture on the surface due to atomisation being too coarse.

Further features include the option of altering the width and height of the spray jet formation (ellipse) and even distribution of liquid across the spray width. No excessively large impulses should be produced on the tablet bed. Based on these requirements a new nozzle has been developed with an anti-bearding air cap, which provides high operating security.

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