Magnetic device for density measurement

A very sensitive device for liquid-density measurements was developed by using a linear variable differential transducer (LVDT) and a magnetic actuator based on an Nd-Fe-B magnet attached to a floater. The device gives 300 mV of output for a change in density of 0.5%. The stability and performance of the device are discussed. Taking into account the fact that the current through the actuator coil is driven directly by a 12-b digital-to-analog converter, changes of 0.001% in the liquid density would be detectable for a dynamic range of 8% in density fluctuations. Actually, small movements in the liquid reduce the sensitivity to 0.01%.<
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