In process plant producing and handling dry particulate materials, rotary valves are widely used and fulfil numerous functions. These include:
- Opening, change-over and shut-off of dry material flow paths
- Dry material flow control
- Protection against excessive or insufficient pressure
- Prevention of incompatible media intermixing at duct/pipe intersection points.
Rotary valve selection and operation has a considerable influence on the hygiene standard of a process line and thus, the end-product quality of the dry material handled. Incorrect selection of valve type and size must be regarded as a serious hygienic risk in the food industry. Hence, only valves strictly conforming to hygienic design standards and suited for hygienic operations must be used. This guideline applies to rotary valves that are in contact with dry particulate food and/or food related materials being processed hygienically in designated dry particulate material processing areas.The objective of this guideline is to provide guidance on the essential requirements for hygienic rotary valve design and operation. The guideline is intended for persons involved in the design, selection, sizing, installation and maintenance of rotary valves required to operate under hygienic conditions.