A clean business: Hygienic system design with HBM load cells

Fresh, natural and carefully treated foods are extremely popular. The demand for juices, milk and smoothies in particular is constantly rising. Hygiene is absolutely essential in their production and for the special packaging. The standards in the beverage industry also applies to the food, pharmaceutical and bio industries. The hygienic requirements for system design - particularly in the sector of packaging - are just as demanding. The use of aseptic packaging technologies in filling processes for sensitive and pharmaceutical products will also continue to increase.

Contamination and cross-contamination with foreign materials must be absolutely excluded from all phases of the production process. A hygienic system design in compliance with the provisions in HACCP and EHEDG – which must also be thoroughly documented – guarantees this. An important role is played here by simple and reliable cleaning - as confirmed numerous times through microbiological investigations.

Fig. 2: SERAC filling system for aseptic filling of liquids such as milk, fruit juices and other foodstuffs

Simple cleaning for optimal hygiene

The design of systems under hygienic aspects – also known as "Hygienic Design" – is a challenge for designers. In order to meet this challenge adequately, the designers must understand the basic microbiological influences in the product area in addition to having solid technical expertise. This includes knowledge of the properties and size of microorganisms, as well as their behavior on the surfaces of various materials. Particularly their growth behavior in gaps and dead spaces.

Accordingly, systems for hygiene-sensitive applications and aseptic packaging come with optimized properties with regards to hygiene: They can be easily dismantled, cleaned and then rapidly reassembled. The materials and components used are characterized by their particular surface properties. Current standards and guidelines such as GMP, FDA, EHEDG, QHD and 3A must also be taken into account. They guarantee high product safety.

Basic requirements for Hygienic Design

Two construction fields must be differentiated regarding the hygienic design of systems: Aspects of hygiene-compliant design are less relevant in sectors where contamination risk is to a great extent excluded. However, where direct or indirect contamination of products is possible, these aspects are extremely essential. The aim here is to recognize and avoid possible problem areas.

The requirements imposed by legislation that areas coming into contact with products must be designed to be "easily cleaned" are decisive for hygienic system design. The following principles must therefore be complied with (source: Dr. Ing. Gerhard Hauser "Hygiene" in "Handbuch der Fülltechnik", Behr’s Verlag, Hamburg 2004):

Selection and use of suitable, approved and easily cleaned materials with the highest possible corrosion resistance
Production of sufficiently smooth, hygienical and easily cleaned surfaces and surface structures
Avoidance of pores, cracks, gaps and all types of defects not visible to the eye on surfaces, fixed and moving joints and bearings
Minimization or optimization of avoidable visible gaps, dents or protrusions (e.g. on static or dynamic seals) that are difficult to clean
Flow-favorable geometric design of construction elements avoiding, where possible, eddy formation through delamination and dead water zones
Avoidance of all types of dead spaces that cannot be cleaned or only with difficulty
Self-emptying or automatically draining design of all relevant areas

In addition, systems must be easy to maintain and easy to access in design. Together with these requirements, it must also be ensured that the materials used are physiologically harmless and food-compatible.

Hygiene is of particular importance here: aseptic weighing systems

The weighing systems used in filling and packaging systems are often used in areas where contamination or cross-contamination is possible due to the direct or indirect contact with products. The requirements for hygienic weighing system design are particularly strict according to EHEDG:

To avoid contamination, only tempered and electro-polished stainless steels with Ra<0.8um can be used. Smooth surfaces must prevent the formation of coatings and adherence of product residues and increase the effectiveness of cleaning. Even frames and housings must be manufactured using high quality stainless steels to avoid corrosion and contamination. Cleaned weld seams are just as obligatory as simple and user-friendly cleaning using bogies or lifting mechanisms. In addition, all applicable requirements for handling must comply with easy cleaning - gaps must not occur in any circumstances.

These requirements apply to the entire weighing system, including all system components such as e.g. load cells.

Globally unique: The HBM PW 27 load cell with EHEDG certification

Specially designed for use in weighing systems for the beverage, food, pharmaceutical and bio industries, HBM offers the only load cell in the world with EHEDG certification for the lower measuring range up to 20 kg - the aseptic load cell PW 27. It also meets the OEML requirements. And it is characterized by its simple cleaning - thanks to an optimized design without edges and corners. Perfect for multihead combination weighers and static scales as well as for filling systems. Particularly practical: System designers do not need to certify the load cell due to the existing EHEDG certification. HBM guarantees compliance with the specified standards.

Further unique plus points of the PW 27: The hermetically sealed load cell (IP68/IP69) made of food-compatible stainless steel is insensitive to the cleaning methods used in the food industry and is characterized by unique reliability in humid application environments. The integrated overload protection, which cannot be blocked by product residues, makes the platform load cell essentially indestructible. Also integrated: An adapter for various cable protection systems, mounting devices and fastening options whose dimensions comply with the standards established on the market.