There is an up/down adjustable switch outside pressure pipe in the housing. As liquid level rising and the displacer immersed, the increased volume of buoyancy force is equal to the weight force of displaced liquid volume by Archimedes principle. As spring elastic force diminishing and spring constriction, the first magnet will move up to trigger the mechanical switch. When the liquid level decreasing, displacer emerges from liquid level, spring receives that added force, and spring increases to a certain length, the first magnetic switch move and the switch is reset to former state by action of first magnetic switch.
Height up to 20 Mtr