Fine Stuff – Custom-built Maier Rotary Joints for a novoflow Wine Filtration System

It’s a long way from the grape to a clarified, palatable wine. In order to get liquids such as wine or beer clarified, it is necessary to filter the product. Company novoflow manufactures filtration systems for the clarification of liquids supplying a great variety of markets and applications. In close cooperation with novoflow, company Christian Maier GmbH & Co. KG has designed suitable rotary joints for a wine filtration system.

Der Geschäftsführer Franz Fastner von novoflow gemeinsam mit dem Gebietsverkaufsleiter Jörg Beßler der Firma Christian Maier GmbH & Co. KG.

Photo: Franz Fastner, managing director of company novoflow® GmbH Umwelt- und Filtertechnik (left) and Jörg Beßler, area sales manager Southeast of company Christian Maier GmbH & Co. KG (right)

Initial Situation

  • Customizing a rotary joint for a special filtration system
  • Meeting the requirements and observing the standards in the food sector

novoflow use the dynamic Cross-Flow process with filter ceramic discs in their filtration systems to reliably separate particles and molecules up to 5 nanometers from the liquid to be filtered. There are several preparation methods in filtration which require, for instance, filter aids for the clarification process. These are not necessary with dynamic Cross-Flow filtration. Inside a container / module, the liquid to be filtered is conveyed over stacked filter ceramic discs which are rotating at up to 500 rotations per minute. The filtrated medium with a filtration grade of up to 0.2 µm accumulates in a rotating pipe in the center of the system and is safely conducted into the drain pipe through a rotary joint. This is where company Christian Maier GmbH & Co. KG comes into it.


Company novoflow designed a wine filtration system for a customer from the food industry which is able to filtrate several varieties of wine in different containers of the system at the same time without mixing them thanks to the dynamic Cross-Flow process.

Special rotary joints are required for this application to ensure the safe discharge of the filtrated medium. The systems and thus the installed components have to meet specific requirements for the contact with food. The specifications of the US Food and Drug Administration (FDA) are particularly worth mentioning in this respect. By now, many food producers all over the world follow the quality standards of the FDA in order to survive in international business. These standards resulted in particular specifications, not only, for example, with regard to food packaging but also to production plants, tubes, hoses, and pipelines.
The system for the production of wine on a vineyard in South Africa required eight rotary joints made of FDA-compliant materials. In order to comply with these specifications, it was of particular importance that Maier’s rotary joints met following requirements:

  • chemical resistance of the materials used
  • electropolished surface and a design free from dead spaces to avoid deposits and contamination through microbial growth
  • it must be possible to empty the rotary joint completely of residues


To ensure that novoflow received a rotary joint which provides a hygienic and reliable connecting link, the engineers of Christian Maier worked together with novoflow to develop a customized solution.

Among other things, particularly the chemical resistance of the materials the rotary joints are made of to the filtrated beverage was of utmost importance in designing. For that reason, a high-quality stainless steel was chosen for the housing and the rotating shaft. To achieve the required surface roughness of less than Ra 0.8 and to prevent the colonization of germs, all surfaces in contact with the product received an especially smooth surface by electropolishing the walls of housings and rotors. In addition to the electropolished surface, the rotary joints were designed and built free from dead spaces in order to prevent deposits and contamination through microbial growth. This means, that all nooks and edges where sediments might deposit were eliminated.

The centerpiece of the rotary joint – the mechanical seal – consists of silicon carbide, a particularly hard-wearing and enduring ceramic material. The spring which provides the required contact pressure of the mechanical seal was placed outside the medium flow to obtain a flow free from stagnation.

To make cleaning of the system possible without any problems, the cleaning method Clean in Place (CIP) is utilized. This means that the system is cleaned by using chemical solutions and rinsing water without the need to dismantle it. For cleaning the novoflow dynamic Cross Flow filtration system, it is backflushed with an acidic or alkaline detergent. This means, the detergent is flushed into the opposite direction of the beverage flow. In order to make such cleaning possible without damaging the rotary joint, the rotating seal was designed to be chemically resistant and to withstand the higher temperatures and pressures of the cleaning process. On the back of it, the rotary joint is splashproof thanks to a stainless-steel cover so that the whole system can be cleaned on the outside as well. Moreover, the enclosed unit has the benefit of additionally shielding the ball bearings which are greased with a special food-safe lubricant, with the result that they are protected against high-pressure cleaning on the outside in an ideal manner.

Finally, to make the rotary joint’s points of intersection safe for application in the food sector, the hose fittings were equipped with clamping flanges to DIN 32676 instead of threaded connections. This sterile flange is used as a typical standard in the food processing industry.

Not least, the flow cross section of the vertically installed rotary joint was design in such a way as to guarantee that the hollow pipe is emptied completely of residues. This ensures, for one thing, that even the last drop of the clarified wine is removed from the system, and for another that the residual liquid can be discharged completely after cleaning.

Benefits of the Customized Rotary Joints by Christian Maier

Jörg Beßler, sales engineer of company Christian Maier, remembers that the close collaboration between Maier and novoflow created real additional value. Due to the customized and universally applicable design of the rotary joints, company novoflow won’t need any of the previously required adapters, conversions and design modifications for future applications. The flow-optimized design, the high-resistance materials and the standardized means of connection make the new rotary joints not only suitable for applications in the filtration of food and beverages but also in other filtration systems, including but not limited to those for the pharmaceutical and chemical industry.

What is more, Mr. Fastner, managing director of company novoflow, emphasizes the fact that the rotary joint does not score with its inner values alone but that the high-class exterior design matches that of their system perfectly. Among other things, all weld seams were made without any interruptions, are perfectly smooth and brightly polished, and the rotary joint is equipped with a stainless-steel cover.

Not least, the application of these reliable and durable rotary joints guarantees an increased production availability of the Dynamic Cross-Flow Filtration system.

About novoflow GmbH Umwelt- und Filtertechnik

novoflow® GmbH Umwelt- und Filtertechnik are well known for their custom-built systems in the line of filtration. These systems are employed in various industries, such as food, pharmaceuticals and chemicals, for the manufacture of medicines and extracts, for the filtration of wine and beer as well as for sewage treatment in biogas plants or in municipal wastewater treatment. From their production site in Rain am Lech, the company distributes systems to customers all around the globe.


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