Float level sensor
AFIMES
ADVANTAGES OF THE DETECTOR
Detection by float allows a direct measurement height of liquid, independent of its density. This measurement will be precise on a great extent (more than 2 meters): for example, on an amplitude of measurement of 1 meter, the precision will be of a few millimetres is +-5%. It is a device which remains simple, and although AFIMES provides detectors to the request and in very small series, their price remains reasonable.
The apparatus consists of a guide tube around with which a float equipped with a permanent magnet commutates without mechanical contact the bistable electrical contacts type "reed" located in the tube. In this guide tube a chain of electrical resistances and a chain of associated relays reed are. The displacement of the float makes rock the contacts of the relays reed to the rise, those taking again their initial position with the descent. Starting from a fixed voltage, the variation of resistance obtained makes it possible to provide a power proportional to the level, with the step (line pitch) of the relays near. This step can be 10 mm what makes a resolution of 1% on an effective range of 1 Mr. the tension taken on the chain of resistances is translated into a standard analogical signal.
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