Seal device for a fluid machine

摘要

A seal device 25B has a wear-ring 31 fixed to a casing 2 of a centrifugal pump and a floating ring 32. An annular gap 36 between an inner peripheral surface of a through bore 32a formed in the floating ring 32 and an outer peripheral surface of a mouth ring portion 19 of an impeller 5B is smaller than an annular gap 35 between an inner peripheral surface of a through bore 31 a formed in the wear-ring 31 and the outer peripheral surface of the mouth ring portion 19. Fluid leakage from a high pressure area to a low pressure area in the casing 2 through the gaps is prevented.