Clean-In-Place (CIP) Design Considerations for Bottom Entry Magnetically Driven Mixers

Author:

Jeffrey S. Gambrill

Engineering Team Leader

LIGHTNIN, A Unit of General Signal 

This technical paper discusses the design considerations for bottom-entry, magnetically driven sealless mixers, focusing on clean-in-place (CIP) applications in the biopharmaceutical and pharmaceutical industries. It compares traditional ceramic sleeve bearings with a new hybrid ceramic ball bearing design, highlighting improved cleanability, reduced particle generation, and enhanced flow-through capabilities. Experimental CIP testing demonstrated that the hybrid ceramic bearing impeller (Impeller A) generally achieved superior cleaning performance across various soils compared to the baseline impeller (Impeller B).

Key Learnings

• Sealless, magnetically driven mixers eliminate conventional mechanical seals, reducing contamination risk and enhancing hermetic sealing.
  
• Clean-in-place (CIP) design is critical for biopharmaceutical applications to ensure product purity and minimize residue buildup.
  
• Bottom-entry magnetic mixers use either face-to-face or co-axial coupling designs, with rare earth magnets optimized for process conditions.
  
• Traditional ceramic sleeve bearings have limitations, including particle generation, brittleness, and restricted flow-through, which can impact cleanability.
  
• Hybrid ceramic ball bearings offer lower particle generation, impact resistance, dry operation, and improved liquid flow through the bearing assembly.
• Optimizing running clearances and minimizing exposed surfaces in the bearing assembly enhances CIP cleanability.
  
• Flow-through bearing designs and impeller configurations that pump fluid through the bearing assembly further improve residue removal.
  
• CIP testing with various soils (BSA, corn oil, honey) confirms that hybrid ceramic bearings generally outperform traditional ceramic sleeve bearings in cleanability.
  
• Evaluating new mixer designs against proven baseline equipment is essential to ensure effective CIP performance.
  
• Proper CIP protocols, including detergent concentration, temperature, and flow patterns, are necessary for achieving high cleaning efficiency.