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Success Story - "FDA compliant mixer shaft seal"
Mixer shaft seal converted for FDA compliance
Based on the standard Simmerring® Radiamatic HTS II, Freudenberg Process Seals has developed a split version of HTS II for amixon, the mixing technology manufacturer.
The background to the joint project was amixon's desire to exploit the advantages of a lip seal for its mixer range. When changing seals an elaborate installation has to be accepted, similar to the change of mechanical seals. The housing or drive has to be removed from the mixer shaft. In addition, there has to be enough free space above the mixer for installation. Consequently, amixon drafted a development objective which was to combine the assembly advantages of the existing stuffing box packing with the hygienic design and longer lifetime of lip seals.
In general the standard PTFE Simmerring® Radiamatic® HTS II is designed for open installation spaces. The split version of HTS II reduces the assembly space as well as the assembly effort. The PTFE body of the seal is machined. With this flexible production method, the lip seal can be customized to installation spaces and operating conditions, opening up decisive advantages when converting from packings to Radiamatic® HTS II seals.
Features of the PTFE Simmerring® Radiamatic® HTS II
The protruding sealing lip without a spring eliminates gaps and dead spaces and therefore avoids product contamination by microorganisms. This FDA compliant rotary shaft seal was developed especially for mixers and stirrers according to hygienic design. The HTS II sealing lip is designed in a way remaining the defined contact surface approximately constant under all operating conditions. This special sealing lip design optimizes the contact pressure and as a result ensures the sealing function. During the installation the sealing lip is compressed elastically and retensions automatically during operation process. The strength of the sealing increases with rising pressure. A rise in temperature also helps to keep the sealing lip in shape. Thus the shaft sealing ring guarantees excellent sealing properties even at high circumferential speed or high pressures. In this way friction and wear are reduced and even dry running conditions and the contact with powders and dust, causes no effect on the lifetime of the Radiamatic® HTS II.
Conclusion
Meanwhile, the project has been completed successfully and amixon has continued to develop its own processing methods so that it can convert existing stuffing box seals on older amixon and Ruberg mixers at its mixing facility to hygienic design lip seals.