Adjustable differential fluid level float indicator

Claim 1

A fluid-level transducer, comprising an elongate outer tube of material transparent to a magnetic field, said tube being adapted for vertical mounting in a region of liquid levels of interest, said tube being closed at its lower end and having a mounting adapter which effectively closes its upper end, an annular float containing a permanent magnet and surrounding said tube for guidance thereon in the course of float action in response to buoyed changes in liquid level, a first elongate suspension tube of magnetically transparent material within said outer tube and fixedly mounted to and suspended from said adapter, said first suspension tube fixedly containing a first hermetically sealed magnetically sensitive electrical switch potted in position near the lower end of said outer tube, and a selectively movable second elongate suspension tube of magnetically transparent material alongside said first suspension tube and within said outer tube and said second suspension tube being adjustably clamped to and suspended from said adapter, said second suspension tube fixedly containing a second hermetically sealed magnetically sensitive electrical switch potted in position in said second suspension tube near said adapter, the substantial range of mountable adjustment of said second suspension tube being such as to position said second switch above the effective elevation of said first magnetic switch for control activation of said second switch.