Detection and indication device

摘要

A device for indicating the presence of electrically conducting particles, such as metal detritus, in a liquid such as hydraulic oil passing through a filter in which a gap is provided adjacent the filter into which metal particles are swept by the liquid flow to form a conducting bridge in an electrical circuit. In a preferred embodiment, an annular gap closed to through flow is provided between an insulated metal ring around a filter element and the wall of the flow passage surrounding the filter, and the ring and the wall are connected to an electrical circuit for actuating a warning light or audible alarm when the gap is bridged.