Using overpressure to protect liquid foodstuffs

Innovative tank pressure unit TPU 500 from Freudenberg Filtration Technologies prevents contamination from liquid foodstuffs during storage and filling.

Whether it is milk or milk-based liquids, cream, raw fruit juices, vegan soy drinks, liquid eggs or sugar-free soft drinks, minimizing the risk of processing such sensitive foods requires the highest levels of hygiene. Silos and tanks in which liquid foods are temporarily stored prior to further processing or filling can be a gateway for bacteria, yeasts and fungal spores. One potential source of contamination is impure air entering the tanks through open vents, for example.

The TPU 500 tank pressure system from Freudenberg Filtration Technologies effectively and permanently keeps germs and harmful particles away from the valuable liquid foodstuffs. The resulting hygienic air quality prevents rejects, protects products from spoiling and protects consumer health. It also ensures high product quality and a long shelf life. This is particularly important when liquid foods are pasteurized or subjected to complex further processing, such as fresh milk for yogurt, curd cheese and cheese, or liquid egg for baked goods and convenience products.

Freudenberg Filtration Technologies offers food manufacturing and processing companies a wide range of filtration materials and filter models in liquid and air filtration as well as dust removal technology. This product portfolio is further enhanced by a comprehensive range of consulting and other services, including engineering all-in-one solutions. The new TPU 500 tank pressure unit is one example of a fully integrated system from a single supplier.

Contamination-free air blanket

The constant flow of clean air provided by the fan creates a blanket of filtered air above the stored liquid inside the silo. Thanks to a slight overpressure, no more unfiltered outside air can enter the silo.


MV HSN NanoPleat or MaxiPleat cassette filter from filter class ISO ePM2,5 65% to ISOePM1 85%


Fan and motor unit

High efficiency fan with energy optimized backwards curved centrifugal impellers; motor with EC technology and integrated controller for constant volume flow.

Final filter

EPA / HEPA filter with aluminium frame, in filter classes E11 to H14


Contamination-free air blanket creates safety corridor

The basic principle is as simple as the details are ingenious. The TPU 500 system creates a germ-free air blanket above the liquid raw, intermediate and end products. Gentle overpressure in this air blanket ensures that no impure outside air can come into contact with the food – even when emptying the tanks and silos. Incidentally, Freudenberg’s hygiene protection system works just as reliably in filling plants in the food and beverage industry. 

Roughly the height of a person, the modular structure consists of fully welded stainless steel housing sections connected by locking latches. Each unit can be customized to meet the customer’s specific onsite specifications and requirements. The modular design of the system makes it easy and safe to change the air filters. The continuous volume flow of the system is regulated fully automatically. The TPU 500 unit continuously monitors the change in pressure and indicates necessary filter changes to operators in good time. This ensures optimized production processes and results in the food manufacturing industry.

Two filter stages ensure regulated air quality

The heart of the system is built around Freudenberg’s filter technology, which has been tried and tested in the food and beverage industry worldwide. Two filter stages consisting of robust prefilters and high-efficiency final filters produce the hygienic air quality. The exact filter configuration varies depending on the application and the local operating conditions. All of the filter series involved are microbiologically inert and harmless in contact with foodstuffs. They meet the applicable food conformity standards and comply with the relevant recommendations of the European Hygienic Engineering and Design Group (EHEDG doc. 47).

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