Mixing shafts in precision mixers are often sealed with stuffing box packing. If their sealing characteristics are good, they offer an advantage: they can be maintained or replaced with little effort. But polytetrafluoroethylene (PTFE) shaft sealing rings are much better suited to the especially hygienic requirements of the food and beverage industry due to their high media and temperature resistance, as well as their consistently excellent sealing characteristics. The separable shaft sealing ring Radiamatic HTS II from Freudenberg Sealing Technologies stands out for its material characteristics, low-dead-space design and convenient installation.
The demountable mixing shaft seal consists of four segments and an O-ring. Two seal segments respectively produce one ring. The two rings are in turn assembled at a 90-degree angle. The four seal segments are made of PTFE E202 and meet the material requirements of the U.S. Food and Drug Administration (FDA), (EC) No. 1935/2004 and EU No.10/2011. The O-ring cord, consisting of 70 ethylene propylene diene monomer (EPDM) 291 elastomer, fulfills the requirements under 3A, FDA and (EC) No. 1935/2004 standards. The separable shaft seal ring is a further development of the standard Radiamatic HTS II. It was developed for FDA-compliant, low-gap and low-dead-space shaft seals in mixers and stirrers. The distinctive design feature of the shaft sealing ring is a special seal lip geometry in which the seal lip is arranged flush on the product side. There is also a precisely defined contact surface that remains nearly constant under all operating conditions. This ensures outstanding sealing characteristics even under severe stresses, such as high pressures or circumferential velocities. It also reduces friction and wear.
The separable Radiamatic HTS II is based on this design principle and can be installed without dismantling the gear unit. That makes this shaft sealing ring from Freudenberg Sealing Technologies a cost-effective and reliable retrofit seal for use in mixers and stirrers subject to strict hygiene requirements.