Hygienic designing


Hygienic designing according to the EHEDG regulations
By Wiebe Pelsma (Manager Engineering Department TBMA Europe)

The fundamental objective of hygienic designing, is the prevention of the microbial contamination of food products. Such contamination may occur during processing and could cross-contaminate subsequent batches of product.

Therefore, the materials we use for construction of our rotary valves have to be suitable for food applications.  For instance: materials, which are in contact with the product, are inert to the product and are unaffected by detergents and disinfectants. They are also corrosion resistant, non-toxic, and their surface finish must not be adversely affected.

Generally stainless steel offers excellent corrosion protection, and is therefore  widely used in the production of rotary valves for food applications. When applied, all the surfaces must be cleanable and not present a toxicological hazard by leaching of components into the food.  Corners should preferably have a radius equal to or larger than 6 mm; and sharp corners (≤90°) must be avoided.

The seals used in rotary valves, must be such that no crevice exists where contaminants can be trapped allowing bacteria to develop and multiply.  The “soft" materials used for the seals must also conform to IEC 1935/2004/2011.

A surface should have a finish of Ra 0,8 or better and be free from imperfections such as pits, folds and crevices. Permanent metal to metal product contact joints, must be continuously welded and free of imperfections.

Also,  all surfaces in contact with product should either be easily accessible for visual inspection and manual cleaning, or it must be demonstrated that routine cleaning completely removes all contamination. 

It is essential that wet cleaning-in-place systems incorporate a drying cycle. The rinse water or steam will itself become a contaminant as it cools if it is not fully removed before the equipment is put back into service.

Learn more about our Quick Clean rotary valves