How to Convey Hygienic Sensitive Bulk materials
Consider Constructive Principles
Several principles apply for all cleaning methods for the hygienic design of the rotary valve and pipe diverter components that are in contact with the product:
- Smooth design in areas in contact with the product
- Surfaces polished to a maximum Ra of 0,8 µm
- Corners and edges with wide radii
- Simple dismantling and easy visibility for inspection during manual cleaning
- Gas purged shaft seals on continuously rotating shafts
- Inert materials (no interaction between the product and component)
Fig. 1 shows an dismantled rotary valve with polished surfaces, suitable for manual wet cleaning or dry cleaning. For automatic wet cleaning (CIP), the metal to metal connections must be equipped with a front-flush seal line as described for the flange connections, as the components are not dismantled. A gap is created in conventional connections with an O–ring seal into which water can penetrate during cleaning due to capillary effects. During subsequent cleaning it cannot be fully ensured that this water is reliably removed. This is prevented with special, front-flush seals with a front–flush sealing line.
Coperion CIP–compliant rotary valves and diverter valves are always equipped with these patented seals. These components were launched on the market several years ago and were therefore the first rotary valves and diverter valves for bulk material systems that were successfully tested and certified by the EHEDG. Such CIP-compliant components are essential for the design and construction of CIP–compliant conveying systems. The company also supplies rotary valves and diverter valves for dry cleaning that have been certified by EHEDG. The components are designed so that they can be dismantled quickly and the connection points are sealed with O–rings.