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Cleanable Solids Processing Equipment and Systems 273
Pharmaceutical Sifter/Screeners
Sifters/screeners are used in anumber of applications for sizing dry intermediates
and bulk products. The sifter/screener use amotor to impart vibration to springmounted
screening decks. Powdered product is moved over multiple-sized screens.
The vibration of the screen causes oversize particles to vibrate across the screen
surface to the screen’s periphery where they arecollected. Undersized particles pass
rapidly through the screens and are discharged through aspout at the periphery of
the bottom collection chamber.
Multiscreen sifters may be used to separate several desirable sizes from a
bulk intermediate. At the conclusion of the processing, fines and small product/
intermediate particulates are often trapped in the screens and gaps and require
cleaning. Traditionally, the sifters and screens are disassembled and cleaned
manually. Advances in design are now allowing manufactures ofsifting/screening
equipment to incorporate CIP technology.
New sanitary sifters for pharmaceutical applications allow for hands-free
wash down by using CIP spray heads (Fig. 18).
In Figure 18, the screener is configured with agap-free screening deck. Unlike
traditional circular screen separators, the pharmaceutical sifter has no gaps between
the mounted screen and the frame wall. This helps eliminate powder buildup on the
outside of the screens. Three CIP spray balls are used with the multilayer screens:
FIGURE 18 Screenerincorporating CIP and
installed spray balls. Source : Courtesy of
Kason Industries, Inc.