Liquid flow detecting device

摘要

A liquid flow detecting device incorporates a static member arranged to be fixed within a passage through which flow of an operating liquid is to take place and an active member held captive by the static member but free to move relatively to the static member to a limited extent in one particular direction at least. The active member has an overall specific gravity substantially the same as that of the chosen operating liquid. Proximity sensing apparatus is included to detect movement of the active member relative to the static member in the particular direction and to issue a corresponding signal.