Hygienic design is mandatory

Load cells for the food industry

There have been some fundamental changes to food production in recent decades. Nowadays, consumers increasingly demand food that is as fresh as possible, without preservatives. Thanks to globalization, some products also have long journeys to make. These developments have resulted in more stringent hygiene requirements during production. Because the resultant products will only last long enough if no germs, or very few germs, get into the food. Perfect compliance with hygiene requirements is only possible if the design of all the systems and components involved in production is geared towards hygiene. This also applies to the sensors that are used, as demonstrated in this article by load cells from HBM.

Excluding micro-organisms from the process

The trend now is for consumers to demand food that if possible, is fresh, untreated and without preservatives. So-called smoothies are a typical example of this type of convenience product. They are made from pureed fruit and fresh fruit juice, without the use of preservatives. To be able to implement this in production, you must try to make it virtually impossible for micro-organisms to get in during the production process. This means that hygiene is crucial in food production plants.

To ensure that the production environment is as hygienic as possible, the systems and components involved must meet certain requirements. The European Hygienic Engineering & Design Group (EHEDG) – a consortium of manufacturers, food producers and research institutes – therefore works on specific guidelines that guarantee the best possible hygiene during food production. An important aspect to be considered here is that all the systems and components used must be as little trouble as possible to clean. The focus is on the geometry and the surfaces that are used.

European Hygienic Engineering & Design Group (EHEDG)

The EHEDG was founded in 1989 as an expert community, with the aim of promoting hygiene and making people more aware of its importance in food processing and packaging. Around 100 companies and institutions in Germany are members of the EHEDG. Its main task is the promotion of hygienic engineering and design is all areas of food production. The organization develops appropriate guidelines and also provides certification. The EHEDG also supports European legislation that requires food to be handled, processed and packaged hygienically, using hygienic machinery, and in a hygienic environment (EC Directive 2006/42/EC for machinery, EN 1672-2 and EN ISO 14159 for hygiene requirements).

Component certification

The certification provided by EHEDG confirms that the components meet the relevant guidelines and thus, in the context of hygienic design, are suitable for use in the food industry. The certification offered by EHEDG distinguishes between open and closed processes, as well as in-process cleaning and cleaning involving dismantling. Tested in all situations is the extent to which components can be cleaned, in order to achieve comprehensive hygiene.

EHEDG has developed suitable test methods to do this. The component is deliberately polluted with bacteria, dried and then cleaned. In a further step, a culture medium with a pH indicator, in which bacteria can reproduce, tests whether any bacteria remain in or on the component after cleaning. If the color changes, this is an indication that bacteria were still present, despite the cleaning. Typical components that are EHEDG-certified include fittings, pumps and sensors. Plant engineers deploying components with EHEDG certification are then able to meet the hygiene requirements of the EU Machinery Directive.

Sensors for the food industry

Discernable in the food industry, as in many other sectors of industry, is the increasing trend towards system automation. The cleaning procedures for this type of system are often automated as well, and must therefore work without the need to dismantle system parts and components. At the same time, automated systems of this type also make increased use of sensor technology. The sensors used must therefore also meet hygiene requirements.

Hygienic load cell PW27

The only platform load cell on the market to comply with the EHEDG guideline is the PW27, which the sensor and measurement technology specialist HBM has specifically designed for this type of food sector application.

  • To meet the high cleanability requirements, the PW27 platform load cell is hermetically encapsulated and is stainless steel throughout. This guarantees that it is compatible with all the cleaning and disinfection agents currently used by the food industry.
  • The design of the PW27 also makes it particularly easy to clean. In terms of geometry, it was essential, for example, for the surfaces on the top of the platform load cell to be inclined. This prevents the collection of dirt or product residue.
  • The developers also had to think of some way of marking the load cell. Hygiene requirements make the usual sticker impossible. Instead, with the PW27, the important characteristic quantities are engraved into the surface by a laser. Despite this, the surface is very easy to clean.
  • Daily cleaning with cleaning and disinfection agents, as well as high-pressure steam cleaning, are standard in the food industry. This is why the platform load cell also complies with high degree of protection IP68 – with IP69K as an option.
  • The platform load cell is available with 10 kg and 20 kg maximum capacity ranges, and has an integrated overload stop to prevent the cell being damaged if the load is too high.

Conclusion

The role of hygienic design in the food and pharmaceutical industries is becoming increasingly important. Thanks to their new load cells with EHEDG certification, the sensor and measurement technology specialist HBM can enjoy a position as a supplier for food and pharmaceutical sector applications. Plant engineers who integrate the load cells into their applications can rely on a guaranteed hygienic design. The initial applications of the PW27 load cell were implemented in multi-head combination weighers for filling machines for the food industry.

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