(252f) Characterization of Spray Guns for the Tablet Coating Industry

Automated spray guns are widely used in fully integrated pan-coating systems. Such pan-coating systems are used by the pharmaceutical/food industries to apply aqueous film, solvent and sugar coating for tablets, confectioneries, and a variety of other products.

Typically, pan-coating systems are supplied from the equipment manufacturer fully configured for a desired application. Often the end user makes necessary changes to the spray gun arrangement in order to accommodate a new application or a change in the coating formulation. Normally, these changes do not produce the expected results due to a less than optimal gun configuration. Frequently, an operator will change the gun operating conditions by simply varying the fluid and gas feeds. As a result, the spray pattern may deteriorate and drop size may increase beyond the allowed size thus affecting the final product quality.

Today, a standard method for optimizing spray guns used in tablet coating applications does not exist. This paper will propose a new method that will include an analysis of the critical elements of atomizer testing. This method consists of layout and overlap optimization to reduce the errors commonly associated with spray manifold application, such as uneven spray distribution, heavy edges and poor overlap. Furthermore, this method will also evaluate the effects of ?normal? operating parameters such as fluid flow rate, atomization pressure, and gun-to-target distance on spray-pattern uniformity, drop size, and velocity.