Ferrofluid-based seal for bioreactor / fermenter
Ferrolabs
The specific feature of these seals is a possibility of working at great shaft wobbling (up to 0.7 mm). FFS include a magnet assembly that consists of (see Fig.1) a permanent magnet 5 and pole tips 1 [2]. The magnet assembly is mounted on the rotary segment 4 of the composite casing. The intermediate sleeve is rigidly fixed in the stationary section 3 of the composite casing. Reverse placement of details is also possible, i.e. mounting the magnet assembly on the stationary segment of the composite casing, and the intermediate sleeve on the rotary segment. The sealed gap created by the pole tips 1 and the intermediate sleeve 11 is filled with ferrofluid 10. To improve the performance of the magnet assembly, circular grooves are made on the pole tips or the intermediate sleeve. The rotary and stationary sections of the composite casing are connected by the bearing support 2 that ensures stability of the sealed gap. The rotary section of the casing is connected to the shaft 8 by the shaft sleeve 6. The spots where these parts are jointed are sealed with elastic rings 7 and 9 that make radial/angular movements of details relative to each other possible. FFS is connected with the sealed fermentor 14 by a flange 13. The FFS casing 3 can also make radial/angular movements relevant to the elastic ring 12.
