| 摘要 |
Provided is an apparatus for detecting a change in a specific gravity of a fluid surrounding the apparatus wherein the fluid moves upwardly and downwardly with respect to the apparatus. The apparatus includes a housing having a top and a plurality of openings for allowing the fluid to enter the housing. A first floatation device is provided having a first specific gravity and being located within the housing. The first floatation device includes a magnet. A second floatation device is provided having a second specific gravity and located within the housing adjacent said first floatation device. The said second floatation device includes a magnet aligned to have the same polarity as the magnet of the first floatation device. A switch fixedly attached to said top, the switch having an open state and a closed state where when one of said magnets is in proximity to the switch, the switch is in a closed state and wherein when both of said magnets are in proximity to said switch, the switch is in an open state. A signaling device is coupled to the switch wherein said signaling device is activated when the switch is in the closed state.
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