Magnetic flowmeter with diagnostics

摘要

A magnetic flowmeter has a tube for supporting fluid flow including a circuit for indicating when the tube is empty to prevent an erroneous flow signal from being provided by the flowmeter, as well as a diagnostic circuit indicating when electrodes in the flowmeter are partially fouled. The circuits include an amplifier connected to two electrodes in the tube and a variable resistor. In a normally operating mode, the amplifier produces an oscillating signal when the tube is empty, and in a diagnostic mode, the amplifier produces an oscillating signal when the electrodes are partially fouled.