A few months ago, I read in the newspaper that an important supermarket chain in France had removed several batches of burgers after detecting traces of the bacteria Escherichia coli (E. coli). This bacteria causes quite a few serious health conditions, and can even be fatal. Its absence from the food industry must be assured and also from other industries such as wastewater plants if, for example, output effluent is to be reused for irrigation purposes.
This one example alone highlights the importance of hygiene in an increasingly globalized food and beverage industry which is far more sensitive to any unhygienic conditions in its production process. Consumption trends increase the risks; more and more products are moving toward being easy to prepare with little or no heat treatment, lower salt content and no CO2, alcohol or preservatives.
But hygiene is not only a concern unique to the food and beverage industry where it has an impact on cleaning/disinfection methods, component design and material selection. Other industries, such as the pharmaceutical or semiconductor manufacturing sectors, or operating rooms in hospitals, are very sensitive to environmental contamination. Clean rooms are commonly used in order to ensure a minimal level of environmental pollutants such as dust, airborne microbes, aerosol particles and chemical vapors are present. For clean rooms, personnel contamination and the design of the HVAC system are the biggest challenges.
Cleaning process and agents
Cleaning in Place (CIP) is a very efficient cleaning/disinfection method frequently used in hygiene-critical environments, such as those found in the food, beverage and pharmaceutical industries. It consists of sequentially circulating, by the inner part of machinery, vessels or pipes, one or several types of dissolved cleaning products and rinsing water, in an automated way, from their respective storage tanks. This cleaning process removes soil, which includes scale, foreign bodies, bacteria (such as E. coli) or yeast spores. The time needed to remove soil is at least 15 minutes when using a suitable chemical at temperatures of 50–85°C / 122–185°F and a pressure of around 2.5 bar. The most commonly used chemicals for soil removal include caustic soda, phosphoric and nitric acids, sodium hypochlorite and peracetic acid (PAA).
But CIP is not the only cleaning/disinfection method used in these industries. A process called foaming (which simplifies the total dissolution of soil) is used, for example, to clean external surfaces of different components. A foam’s pH can range from acidic to highly alkaline depending on the chemicals it contains and it is rinsed normally using medium-pressure water. This combination means that components exposed to these wash-down areas must be able to withstand these broad pH range conditions while also featuring a high IP grade in order to be protected against the medium-pressure water jets used for rinsing.
The other common cleaning process, steam sterilization, is typically used for the sterilization of glass bottles in the beverage industry. However, due to the high temperatures in the steam sterilization process, it’s not as commonly applied in situations where plastic containers, such as PET bottles, are used. Very specialized machines and components intended to be used in these conditions require specific certifications to be properly applied to alleviate the risk of failures.
Hygienic design in the Danfoss Drives portfolio
Danfoss Drives offers a combination of AC drive and energy-efficient permanent magnet gear motor in one package called the VLT® FlexConcept®. This package consists of the VLT® Decentral Drive FCD 302, the VLT® AutomationDrive FC 302 and the VLT® OneGearDrive®.
Both the VLT® Decentral Drive FCD 302 and the VLT® OneGearDrive®, in their hygienic configurations, are EHEDG certified, Type EL Class I, for closed equipment, wet cleaned-in-place (CIP) without dismantling. In short, the VLT® FlexConcept® features products that are suitable for use in wash-down areas as long as they are not steam-sterilization ones.
To achieve this rating, we take some key steps to ensure that the products are easy to clean and to avoid any areas where micro-organisms can grow (for example, dead areas, gaps and crevices). In practice, the use of external fans is avoided, the products are finished with perfectly smooth surfaces and don’t have sharp corners and are assembled in such a way that ensures that seams and crevices are not present.
Both the VLT® Decentral Drive FCD 302 and the VLT® OneGearDrive®, in their hygienic configurations, are supplied with a lacquer finish with aseptic, hydrophobic and non-polar behavior designed to avoid re-contamination, to ensure resistance against an environment that includes cleaning agents from pH 2 to 12, and to offer a smooth surface (Ra < 0.8 µm, according to ISO 4287 standard) for short cleaning times. They feature high environmental protection class packaging, IP 66 / UL Type 4X enclosures for the VLT® Decentral Drive, and IP 67 / IP 69K / UL Type 4X for the VLT® OneGearDrive®. IP 69K, although not included in the IEC 60529 standard, but instead in the German standard DIN 40050-9, assures protection against cleaning processes using high-pressure water jets (80–120 bar / 1160–1450 PSI) at high temperatures (80°C / 176°F).
The VLT® OneGearDrive® has some additional features and options that make it particularly suitable for hygienic areas. The VLT® OneGearDrive® motor and gear are assembled together with a seamless, crevice-free fit. Also, the included gear can be filled with a special oil suitable for the food sector (NSF USDA H1 type) in order to avoid incidental contamination of food. The shaft can also be supplied with an AISI 316 stainless steel construction, which is the recommended type in EHEDG guidelines for shafts for cleaning temperatures in the range of 50–150°C / 122–302°F and chlorides concentration over 100 ppm, due to its corrosion resistance and strength. Lastly, motor and encoder connections are made with the Danfoss CleanConnectTM stainless steel connector system.
A decentralized drives solution as an option
All the features emphasized in the previous point allow a flexible location of the VLT® Decentral Drive FCD 302 in a food and beverage plant. So a decentralized approach can be followed using the VLT® Decentral Drive FCD 302 or a centralized one, using the VLT® AutomationDrive FC 302. The final choice will depend, among others, on space constraints, acceptability of the end user, cabinet/control room costs versus cabling costs and possible electromagnetic problems. The matrix below gives an overview of the recommended combinations of motors and drives for differing production areas.
To cut a long story short, Danfoss Drives has the technical solutions in place to avoid dangerous situations as in the case of the French supermarket chain highlighted at the beginning of this post. We also provide products with precise positioning and synchronization functionality that optimizes the performance of many applications in the food and beverage industry such as conveyors and labelling and packaging machines. Watch this video to see how the VLT® FlexConcept® has helped improve performance and reduce consumption in a bottle-filling plant.
Check back regularly with us here at FocusOnDrives.com for frequent updates on the best ways to ensure that your investments in AC drives are always the safest investments around. Next time, in Part 10 in the “It’s a harsh world…” series, Drives vs. Nature, we will discuss how the ever-changing weather conditions of the outdoors affect the operation of your AC drives. Additionally, let us know in the comments what environmental impacts give you the biggest challenges and how we can help you overcome them. Regardless of whose name is on the label, we’re here to help! In the meantime, you can find out more about all our products here.
Abraham González Ponce, Application Knowledge Manager, Application & Service Products, Danfoss Drives
Jake Roeder, Global Product Marketing Manager, Danfoss Drives