| 摘要 |
PROBLEM TO BE SOLVED: To provide a shaft seal which uses a contact type seal as a primary seal and a magnetic fluid as a secondary seal, and which can always stably hold a sealing performance even when it is used in such a condition that it makes contact with an organic solvent. SOLUTION: In a magnetic fluid type shaft seal composed of a primary seal 2 and a secondary seal and using a contact type seal as the primary seal 2 and a magnetic fluid as the secondary seal, the magnetic fluid 4 is mainly composed oil of perfluoropolyether exhibited by F[CF(SF3 )CF2 O]nRf (where Rf is a perfluoro low class alkyl group, and n is larger than 5 in average, and preferably between 15 and 20), and is filled into a minute aperture defined in a magnetic circuit. |
