Germ-free cables

Wherever food is involved, hygiene is at the top of the agenda. Production facilities should therefore be produced according to the principles of Hygienic Design. The Lapp Group thus offers a wide range of cables and accessories – and just as, if not more, importantly, consultation for selecting and using the right products in an application.

Specialised cabling solutions developed specially for the industry such as SKINTOP® HYGIENIC and ÖLFLEX® ROBUST are designed to satisfy even the most stringent requirements of the industry.

Specialised cabling solutions developed specially for the industry such as SKINTOP® HYGIENIC and ÖLFLEX® ROBUST are designed to satisfy even the most stringent requirements of the industry.

Production facilities which are constructed according to the principles of Hygienic Design represent a huge step forward in terms of optimising quality, safety and ultimately efficiency in the food and beverage industry. They are constructed in such a way they do not allow germs to settle and can be cleaned easily. They are also particularly robust. The Lapp products that meet the particularly stringent requirements of Hygienic Design include, for instance, the cable gland SKINTOP® HYGIENIC. It follows the general design principles of DIN EN 1672-2 for the food and beverage industry and is certified according to the latest EHEDG testing. Furthermore, the cable entry – just like the cable conduit SILVYN FG NM and the ÖLFLEX® ROBUST cable – meets the ECOLAB® requirements relating to resistance to cleaning agents and disinfectants. The SKINTOP® HYGIENIC does not provide any surfaces for contaminants to attack. All seals are fixed tightly to the cable and connection point with no gaps. Instead of an O-ring, it has a radial moulded seal above the connection thread, a sealing ring below the domed cap nut and a specially formed conduit sealing ring on the cable. It has smooth surfaces and no edges, meaning that remaining food cannot settle there and can easily be washed off.

 The three types of hygiene zones

While hygiene is always important, the extent of its importance varies. The closer a component comes to foodstuffs, the greater the requirements. Generally, there are three types of hygiene zones:

  • Product zones: these regularly come into contact with foodstuffs. Examples include stirrers, filling nozzles, blades and cutters.
  • Spray zones: these are areas and machines which come into contact with foodstuffs, for example through spraying. Generally, a surveyor or the producer conducts a risk assessment to determine whether the food can return to the product zone.
  • Non-product zone: these include all areas and facilities in a factory which do not come into direct contact with the foodstuffs. However, these areas are often cleaned together with the more sensitive areas, which in turn may result in high chemical and mechanical stresses.

Resistant to cleaning agents

In the spray zone and the product zone, the most stringent hygiene requirements apply. These zones need to be cleaned particularly frequently and thoroughly. This is generally the responsibility of the cleaning crews who work at piece rates and use strong cleaning agents such as corrosive acids and alkalis in different concentrations – they dry surfaces by wiping them down or using hot steam jets. Few materials are able to withstand this in the long term, the main one being stainless steel, which is used most of all in the product zone, where it is virtually the only material used. If cables need to be installed in the product zone the choice is limited to extremely tough types, such as the ÖLFLEX® ROBUST.


Loops along the cables trap dirt and are tough to clean and therefore should be avoided in food production.

Loops along the cables trap dirt and are tough to clean and therefore should be avoided in food production.

Beyond this, another one of the main challenges is the installation type: cables are often bundled more tightly together than they ought be, or they are not easily accessible. Loose cabling with a bit of "play" would be ideal for easy cleaning. However, technical inspectors normally place great importance on the use of fixed installation – a happy medium needs to be found. The Safe Food Factory participants recognised that overly long cables represent a problem: cables are often installed with some excess length so that there is a reserve – while this is a comfortable approach, it is also problematic, firstly in terms of electrical engineering (keyword bundling) and secondly because the loops that form are often tough to clean and dirt gets trapped in them.


The participants generally established that the cables should ideally be installed in such a way that they are as far away as possible from the intensive cleaning processes. Additionally, hybrid cables can be used. If several cables are combined into one, there is then less cable space and less intermediate space in which impurities can accumulate.


If cables are installed in the product zone, for example for a temperature or level sensor in a fermenter, they need to be particularly well protected. They are often then installed in stainless steel pipes – which of course represents a significant cost factor. Therefore the current trend, at least in the spray zone and the non-product zone, is to install cables openly or in protective conduits. This of course means that they need to be particularly resistant to acidic and alkaline cleaning agents and hot steam.


The conduit gland SILVYN® HYGIENIC, for instance, has no grooves in which residue can settle, unlike conduits used in mechanical engineering. It is blue, as the sector requires it to be. If a piece of plastic were to somehow fall into the food, it would be easier to detect it this way because in nature there are no materials with such an intense blue colour. This is also the case for the cable ties, which Lapp provides especially for the food industry. They are blue as well and also contain an admixture of metal. This means that a missing cable tie can be retrieved very easily using a metal detector or an X-ray unit.


There is a further complication for applications with large temperature fluctuations, as condensation can form and collect in the protective conduit – this too is unhygienic in the long term. In this case, the better option is to use an openly installed and highly durable cable in connection with an appropriate cable gland, for example an ÖLFLEX® ROBUST with the cable gland SKINTOP® HYGIENIC. This example highlights that there is no universally applicable best solution – each case needs to be individually assessed, and the application consultants at Lapp help customers to find the best solution.


In terms of product development, Lapp is taking a pragmatic approach. Instead of reinventing the wheel and developing expensive special products, wherever possible the company uses existing products from mechanical and plant engineering in the food industry as well. And this is the case for a whole range of cables, such as the classic ÖLFLEX® ROBUST, a series of cables which are not only resistant to machine oil in industrial production, but also cleaning agents in food production. Lapp offers a wide selection of accessories and suitable cables with sheaths made from PVC, TPE and PUR, some of which have undergone ECOLAB® testing. If requirements are not met by existing solutions, specific branch-related ones are developed such as SKINTOP® HYGIENIC or SILVYN® HYGIENIC.