Fischer & Porter Company

Fischer & Porter Gmbh

Klaus Schafer

Peter Nissen

Albert Seebode

Werner Marchewka

Karl-Heinz Rackebrandt

A device for measuring the flow of a fluid through a measuring pipe, includes a first coil arranged above the measuring pipe, a second coil arranged below the measuring pipe, and a pair of electrodes facing one another, on the sides of said measuring pipe. The coils are excitable and produce both aiding and opposing magnetic fields. A correction circuit corrects the voltage (U.sub.r) between the electrodes. The corrected voltage is approximately proportional to the fluid flow in the presence of aiding magnetic fields when the measuring pipe is partially filled. The correction circuit provides correction to an output signal (S) corresponding to the flow of the fluid when the measuring pipe is partially filled by means of a correction function to a corrected voltage (U.sub.t) which depends on the voltages (U.sub.r, U.sub.g) between the electrodes in the presence of aiding and opposing magnetic fields. The correction function is accomplished by employing a detecting electrode which is arranged at the top of the measuring pipe for detecting complete filling of the measuring pipe. The potential generated by the detecting electrode controls a circuit such that when the measuring pipe is completely filled, the circuit generates voltage (U.sub.r) corresponding to the aiding magnetic fields as an output signal (S), and when the measuring pipe is partly filled, the circuit generate the corrected voltage (U.sub.t) as an output signal (S).

Device for measuring the flow of fluid through a measuring pipe

A device for measuring the flow of a fluid flowing through a measuring pipe includes coils arranged above and below the measuring pipe and a pair of electrodes facing each other on the sides of the measuring pipe. The coils are excitable for producing aiding and opposing magnetic fields. A correction circuit corrects the voltage between the electrodes, which is only approximately proportionate to the flow of the fluid in the presence of aiding magnetic fields, to an output signal S which is proportionate to the flow of the fluid, by means of a correction function Ug/Ur which depends on the voltages Ur,Ug between the electrodes in the presence of aiding and opposing magnetic fields. Separate correction signals are determined depending on whether the Froude number of the flow in the measuring pipe is greater than or less than one. One of the correction signals is applied to the voltage Ur which corresponds to the aiding magnetic field, for producing an output signal S.

Device for measuring the flow of a fluid flowing through a measuring pipe

Fluid flowrate measuring apparatus in which magnet coils, positioned symmetrically about a pipe through which fluid flows, are excited to generate magnetic fields during four periods of an excitation cycle which are additive during the first period of excitation, opposing during the second period of excitation, additive during the third period of excitation in an opposite sense to that during the first period, and opposing during the fourth period of excitation in an opposite sense to that during the second period. Electrodes, which sense fluid flow through the magnetic fields, develop signals representative of fluid flow through the pipe during the four excitation periods and these signals are processed to develop a flowrate measurement signal.

Fluid flowrate measuring apparatus

An electromagnetic flowmeter whose primary includes a flow tube through which the fluid to be metered is conducted to intersect a magnetic field and thereby induce a voltage therein that is transferred to electrodes to produce an electrode signal as a function of flow rate, which signal includes a noise voltage. The electrode signal is applied to the input amplifier of a secondary whose output is fed to one input of a summing stage, the output of which is fed to a range amplifier that yields a test voltage, the input and range amplifiers producing offset voltages. To compensate for the noise and offset voltages, a compensation voltage is derived from the test voltage and applied to the other input of the summing stage. This compensation voltage is produced only when the test voltage exceeds a predetermined threshold value.

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Munden, Germany

Klaus Schafer