Rosemount Inc.

Micromotion Gmbh

Robert K Schulz

Scot Ronald Foss

John D Pro

Kirk Allan Hunter

William F Graber

William G Totenhagen

Thomas H Junkans

A magnetic flowmeter for measuring flow of a flow of process fluid, includes a flow tube arranged to receive the flow of process fluid therethrough. A magnetic drive coil proximate the flow tube is arranged to apply a magnetic field to the flow in response to a drive signal. At least one electrode is arranged to sense an electrical potential of the process fluid which related to the applied magnetic field and flow rate of the process fluid. Temperature measurement circuitry is coupled to the magnetic drive coil and is configured to provide a temperature output indicative of temperature of the drive coil based upon an electrical parameter of the drive coil. Flow measurement circuitry coupled to the at least one electrode is configured to provide a flow output based upon sensed electrical potential.

Magnetic flowmeter for measuring flow

A magnetic flow meter includes a flowtube arranged to receive a flow of process fluid and a coil proximate the flowtube arranged to apply a magnetic field to the process fluid. A sense electrode is arranged to sense a voltage potential in the flowtube in response to the applied magnetic field. The sensed voltage is indicative of flow rate of process fluid through the flowtube. Diagnostic circuitry provides an output related to an electrical path between the coil and electrical ground.

Magnetic flowmeter with coil ground path detection

A magnetic flowmeter is provided including a magnetic flowtube arranged to receive a flow of process fluid. The magnetic flowtube includes a drive coil and at least one sense electrode. Measurement circuitry is coupled to the flowtube and is configured to provide a drive signal to the drive coil and measure flow of process fluid through the flow tube based upon an output from the sense electrode. A memory contains a stored value related to a nominal parameter of the flowtube. Verification circuitry is arranged to measure a parameter of the magnetic flowtube and responsively provide a verification output related to operation of the magnetic flowmeter based upon a comparison of the measured parameter and the stored value.

Magnetic flowmeter with verification

An analysis circuit in an electromagnetic flowmeter provides diagnostic operating conditions and identifies one or more of the diagnostic operating conditions for which the coil current is stable during a sample interval. A diagnostic operating condition is selected as a measurement operating condition as a function of a noise floor measurements of the electrode voltage.

Noise diagnosis of operating conditions for an electromagnetic flowmeter

A magnetic flowmeter transmitter includes a flowtube and measurement circuitry which provides an output related to flow through the flowtube. Output circuitry, such as analog and pulse output circuitry, provides transmitter output(s) related to flow through the flowtube. Output verification circuitry of the transmitter is coupled to the output circuitry and provides verification of proper operation of the output circuitry by analyzing the output signals.

Magnetic flowmeter output verification

A magnetic flow transmitter includes a calibration converter that performs a calibration calculation routine to produce a calibration constant that couples to a flow converter. A data set input couples a flowtube data set that is associated with a unique flowtube to the calibration converter. A data table associates multiple flowtube data sets with multiple calibration calculation routines. The data table couples a calibration calculation routine that is unique to the flowtube data set to the calibration converter.

Magnetic flow transmitter having multiple flowtube data sets

An electromagnetic flowmeter for measuring a flow rate of a fluid in a pipe is described. A pipe carries a fluid. A magnetic coil is disposed adjacent to the pipe for inducing a magnetic flux in the fluid. A plurality of electrodes are disposed within the pipe, and the plurality of electrodes are electrically isolated from one another. Measurement circuitry is coupled to at least one of the plurality of electrodes and is configured to measure flow rate as a function of a potential across the plurality of electrodes. An empty pipe detector is coupled to at least one of the plurality of electrodes and is adapted to detect an empty pipe condition based upon an adjustable test criteria. In one embodiment, a local operator interface is coupled to the empty pipe detector for adjusting the adjustable test criteria.

Tunable empty pipe function

An magnetic flow meter is provided which includes a reference electrode configured to electrically couple process fluid flowing within a flowtube of the flow meter. The reference electrode is adapted to measure potential of the process fluid. A current limiter is configured to limit current flow through the reference electrode and thereby reduce corrosion of the reference electrode.

Magnetic flow meter with reference electrode

A magnetic flowmeter system provides a volumetric flow rate output and includes flowmeter electronics for coupling to a flowtube assembly. The flowtube assembly includes a coil which receives a magnetic field producing coil current from a supply circuit in the flowmeter electronics. The coil produces a magnetic field which generates an EMF in the field representative of flow. An EMF sensor senses the generated EMF and provides an output indicating flow. The supply circuitry is coupled to coil wires of the coil and is responsive to a control signal. A sensor senses the frequency response of the coil and generates a sensor output. A comparator compares the sensor output with a predetermined level and provides a comparator output based upon the comparison. Control circuitry provides the magnitude control signal to the current based upon the comparison.

Current selection circuitry for magnetic flowmeter

A magnetic flowmeter system provides a volumetric flow rate output and has a coil receiving a magnetic field producing coil current from the current supply circuitry. The current supply circuitry includes an H-bridge transistor circuit having first and second switches which couple one of the first and second coil wires to a supply conductor. Third and fourth switches of the bridge circuit couple the other of the first and second coil wires to a second supply conductor. A control circuit periodically alternates conduction of the first, second, third and fourth switches to reverse the polarity of the coil current. A coil current control circuit generates a non-alternating output representing the sensed alternating coil current amplitude. The control circuit modulates the conduction duty cycle of the third and fourth switches as a function of the non-alternating output to regulate the coil current amplitude to a selected level.

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Excelsior, MN, United States of America

Robert K Schulz