VDW Verein Deutscher Werkzeugmaschinenfabriken e.V.

For more than 40 years COMBER has been manufacturing the PRESSOFILTRO® filter and filter-dryer for pressure and vacuum operation. Several hundred machines are being used for discontinuous solids/liquid separation, followed by efficient cake washing, also using reslurrying, as well as vacuum drying of the product. In compliance with cGMP and FDA guidelines. Also available in sterile design. Calculation, design and manufacture in accordance with ASME pressure vessel code, Section VIII, with U-Stamp and/or Pressure Equipment Directive (PED) 97/23/EC. Suitable to process a wide range of products. Frequent production changes. Very easy internal cleaning using CIP system.

Pressofiltro® PF nutsche filters or filter dryers are versatile units designed for multipurpose production facilities. To meet the demanding requirements for filters used in the manufacture of pharmaceutical ingredients, the filters are designed to meet stringent cGMP and FDA guidelines.

To allow for good cleanability using CIP systems and to permit optimal inspection after the cleaning process all product wetted surfaces are designed without dead areas, with smooth transitions of internals and without any bolted connections. For good access to the filter internals for cleaning and inspection purposes the filters are equipped with an openable filter base. The overall attention to design details allows for simplified validation of the units.

The agitator is supported from the top, with the agitator drive, the bearings and the shaft seal installed externally. Shaft sealing is with a double mechanical seal and a convoluted bellows. The agitator arms with specially designed bottom teeth smooth and press the cake when rotated counterclockwise, and mix and agitate the cake when rotated clockwise. Simultaneous rotational and vertical agitator motions result in a very efficient and even mixing of the entire product mass for mixing and drying. The agitator arms are S-shaped for improved product discharge.

All product wetted surfaces are heated to obtain the largest possible heat exchange area for short drying times and a low attainable final humidity. Supplemental microwave heating is available to further reduce drying times.

The product is discharged through a hydraulically operated side discharge valve, with the valve plug contoured to match the curvature of the vessel internal wall. The solids discharge valve is a metal to metal seal design with the sealing surfaces arranged outside the product flow path, with interchangeable seal rings. This assures proper sealing even after multiple operations during a batched discharge.

Alternatively the product can be discharged through an active or passive isolator (glove box). On smaller filter units the isolator permits contained sampling, product discharge and heel removal all in one system. For larger filters different heel break-up and heel removal devices are available.