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The Top-5-Challenges for sealing Mixers & Agitators!

Mixers and agitators place special demands on dynamic sealing solutions.

Mixers and agitators are used in the food and beverage industry as well as in the pharmaceutical industry. Machine builders and operators of mixers and agitators are often faced with special challenges.

Challenge 1: Hygienic manufacturing & cleaning processes

The hygienic production of the various products in the food and beverage industry requires special attention when choosing a sealing solution. In the past, mixing shafts were often sealed with stuffing box packings. This solution is unsuitable from a hygienic point of view. A suitable sealing solution must comply with hygienic design. A component in hygienic design is designed to be cleanable and excludes microbial and particulate contamination of the end product in a hygiene-critical production environment. Hygienic seals must therefore be designed to be free of dead space.

The media in the production cycle as well as the cleaning cycle must be safely sealed. The cleaning processes are carried out by means of CIP (Clean-In-Place) as well as SIP (Sterilization-In-Place). The CIP process is a cleaning method in which individual fully automated processes run according to strictly specified parameters. The cleaning temperatures are determined according to the application and are usually around 90°C. The CIP process is followed by sterilization using the SIP process. Here, in automated processes, active microorganisms are killed at around 140°C using hot water or steam, depending on the application. The use of chemical disinfectants is also possible during this process.

Sealing solutions must therefore be particularly temperature-resistant, resilient, and have excellent chemical media resistance.

Challenge 2: Abrasive media

Abrasive media also present special challenges for sealing solutions in the food and beverage industry. Abrasive media can be crystalline structures such as sugar, as well as powders, grains and many other organic and inorganic starting materials for the end product.

These dry ingredient blends require outstanding wear resistance of the seal materials and compounds as they are mixed together at high peripheral speeds.

Challenge 3: Vacuum mixing

In the food, pharmaceutical and cosmetics industries, the starting media are often mixed under high pressure and vacuum. The process steps take place one after the other or in parallel in a closed system. The materials of the sealing solutions must therefore be able to withstand high pressures and extreme vacuum processes in addition to all other requirements.

Challenge 4: Contamination

The choice of a suitable sealing solution prevents negative effects on the production of food and beverages. A negative impact could be, for example, cross-contamination of different formulations, which could render a complete batch unusable. If contamination that was trapped in the seal and then later leaked into the batch that could have dangerous consequences. But wear and tear on a sealing solution can also lead to leakage, which can shut down production. In the case of a dry run, it must also be ensured that the sealing solution can withstand this stress.

All this means a high demand on the sealing solutions: Several times a day, different dry and/or liquid ingredients are mixed together under the influence of high temperatures and sometimes under vacuum, cleaning processes with chemical cleaning cycles take place, the mixing process is repeatedly stopped and started.

Challenge 5: Requirements & Certificates

A suitable sealing solution should meet all essential certifications for the food and pharmaceutical sector, so that machine builders and operators of mixing plants and agitators can be sure that their equipment complies with all regulations and requirements. Particularly noteworthy are: EC 1935/2004, FDA and USP Class VI.

The perfect sealing solution for mixers and stirrers: Garlock PS-SEAL ®

The PS-SEAL® product family stands for reliable sealing of rotating shafts at high circumferential speeds, high pressures, and extreme temperatures. Abrasive media are sealed just as reliably as aggressive media.

Garlock PS-SEAL®:

  • Useable under high pressure and in extreme vacuum
  • Very suitable for high circumferential speed
  • Temperature resistant from -90°C up to +260°C
  • Excellent chemical resistance
  • Useable in food and pharma applications due to FDA conformity, EC 1935/2004, and USP Class VI
  • SIP/CIP compatible
  • Good dry running capability
  • Wear resistant and low friction

Garlock PS-SEAL® – in countless configurations and lip and seal materials to meet any individual requirement.

PS-SEAL® sealing solutions meet many different requirements faced by plant designers and operators due to their unlimited combination possibilities.

Find more information about PS-SEAL® here…

Garlock GmbH
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41468 Neuss
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