open access

https://hdl.handle.net/2115/84427

Magnetic fluid seals working in liquid environments: Factors limiting their life and solution methods

英語

Water

2020-04-15

Elsevier

Journal of magnetism and magnetic materials

500

166293

A magnetic fluid (MF) seal enables mechanical contact-free rotation of a shaft and hence has excellent durability. The performance of an MF seal, however, decreases in liquids. Factors limiting seal life are MF flowing away and mixing of MF with liquids. We developed an MF seal that had a "shield'' mechanism. Two types of shield were placed in MF seals installed in rotary pumps. Long-term durability tests were conducted. The MF seal with a shield having a small cavity space showed a longer life (207+ days), while the MF seal with a shield having a large cavity space failed after 28, 32 and 31 days. When a rotary pump is connected to an afterload, water flows into the cavity space of the shield through a concentric annulus and compresses air in the cavity. The water flow stops once the air pressure equilibrates the afterload pressure. Water remained in the entrance annulus and did not make contact with the MF in the case of the shield having a small cavity space, while water entered the cavity space and made contact with the MF in the case of the shield having a large cavity space. Less water in contact with the MF prolonged the seal life. In conclusion, the use of an optimally designed shield prolongs an MF seal life by preventing the MF from flowing away and mixing with liquids.

学術雑誌論文

Accepted Manuscript

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