Fischer & Porter Company

Eggert Appel

Wilfried Kiene

Peter Nissen

Gottfried Geisler

Dieter Meier

Albert Seebode

Robert J Augustine

Thomas L Picone

Rudi Kuchemann

Herbert Gehrke

An electromagnetic flowmeter in whose primary the fluid to be metered is conducted through a flow tube to intercept a composite magnetic field to induce therein a voltage which is picked up by capacitive metering electrodes. The composite field is formed by a low-frequency comparison field having a long period on which is superimposed a high-frequency switching field having a short period. The voltage from the capacitive electrodes is fed by way of a high pass filter to the input amplifier of a secondary whose amplified output is analyzed to provide separate components, one originating from the comparison field and the other from the switched field. An output signal is produced in accordance with the time phasing of these components, after compensating for the signal loss experienced in the filter by the comparison field component by means of a compensation voltage derived from the switched field component.

Capacitive type electromagnetic flowmeter

A magnetic flowmeter which includes a spool formed by a metallizable ceramic whose dielectric constant is at least 25 through which the fluid to be metered is conducted. The outer surface of the spool is metallized in its central region to define a pair of capacitative metering electrodes at diametrically-opposed positions, an electromagnetic field being established within the spool whereby when the flowing fluid intercepts this field, an emf is induced therein to produce a signal at the metering electrodes which is a function of flow rate. Overlying each metering electrode and projecting from the spool is a ceramic block whose outer surface is metallized to define a shield electrode which covers the metering electrode.

Electromagnetic flowmeter with capacitance type electrodes

A magnetic flowmeter which includes a spool formed by a metallizable ceramic through which the fluid to be metered is conducted. The outer surface of the spool is metallized in its central region to define a pair of metering electrodes at diametrically-opposed positions, an electromagnetic field being established within the spool whereby when the flowing fluid intercepts this field, an emf is induced therein to produce a signal at the metering electrodes which is a function of flow rate. Overlying each metering electrode and projecting from the spool is a ceramic block whose outer surface is metallized to define a shield electrode which covers the metering electrode.

Magnetic flowmeter

An electromagnetic flowmeter which includes a flow tube through which the fluid to be metered is conducted, the fluid intercepting a magnetic field to induce a voltage therein which is transferred to a pair of electrodes mounted at diametrically opposed positions on the tube. The inside surface of the meter tube is protectively lined with a stable liner assembly constituted by a three-dimensional stiffening structure embedded in an insulating layer which conforms to the surface.

Insulating liner for electromagnetic flowmeter tube

A magnetic flowmeter which generates a signal proportional to the flow rate of a fluid passing through a pipe to intersect a magnetic field whose lines of flux are substantially parallel to a transverse axis normal to the longitudinal axis of the pipe. The flowmeter includes two electrode assemblies mounted on the pipe on opposite sides of the transverse axis and capacitively coupled to the fluid. The effective coupling capacity of the electrodes in each assembly is such as to render the signal substantially immune to the influence of non-axisymmetric flow profiles.

An electromagnetic flowmeter system whose electromagnets are excited by a direct-current source through switching means operating at a predetermined drive frequency to generate a pulsatory current establishing a magnetic flux field in the flow tube through which the fluid to be measured is conducted. The fluid intercepting this field induces a pulsatory voltage in the metering electrodes mounted at diametrically-opposed positions on the tube. The electrode voltage is applied to an analyzer which includes a sampling switch operating in synchronism with the drive frequency to extract pulses from the electrode voltage during the magnetic flux steady state intervals thereof. These pulses, which are rich in harmonics, are fed through a filter that selects one of the harmonics to yield a harmonic signal which is demodulated to produce an output signal free of disturbances.

Electromagnetic flowmeter system

An electromagnetic flowmeter in which the fluid to be metered is conducted through a flow tube formed of nonmagnetizable metal and provided with an inner lining of electrical-insulating material. The fluid intercepts a transverse electromagnetic field established in the tube whereby the voltage induced in the fluid is transferred to a pair of electrodes disposed at diametrically-opposed positions on the tube to yield a signal indicative of flow rate. The electromagnet is constituted by at least one solid core surrounded by a coil to which a low-frequency excitation current is applied, the core having a cavity in a region therein which serves to reduce the mass of the core without, however, significantly affecting the intensity of the magnetic field produced thereby.

Electromagnetic flowmeter

An electromagnetic flowmeter in which the fluid to be metered is conducted through a flow tube provided with a pair of diametrically-opposed electrodes. The fluid intercepts a magnetic field established in the flow tube by a magnetizable core having a coil wound thereon through which an excitation current flows, thereby inducing a signal voltage in the electrodes. Because the permeability of the core is temperature-dependent, changes in temperature affect the strength of the magnetic field and adversely influence the signal voltage. Compensation means are provided to render the signal voltage independent of temperature, thereby producing an output signal accurately proportional to flow rate.

Temperature-compensated electromagnetic flowmeter

An electromagnetic flowmeter in which a fluid to be metered is conducted through a flow tube formed of a non-magnetizable, weldable metal pipe having an insulating liner therein and provided with a pair of diametrically-opposed electrodes. The fluid passing through the tube intercepts a magnetic field to induce a signal in the electrodes indicative of flow rate. The magnetic field is established by a magnet system excited by a low-frequency alternating or pulsating current, the system including at least one solid core of ferromagnetic material about which is wound an excitation coil. The core has its inner face welded to the outer surface of the pipe to provide a highly stable magnet system.

Magnet system for electromagnetic flowmeter

An electromagnetic flowmeter capable of measuring fluids having any degree of conductivity, including fluids having dielectric properties. The fluid to be measured is fed through a dielectrically-lined flow tube to intersect a transverse magnetic field, thereby inducing a voltage in a pair of planar detecting electrodes disposed within the dielectric lining. Each detecting electrode and an associated planar shielding electrode are unitized in an assembly wherein the electrodes are embedded in a liner segment formed of rigid dielectric material, connections to the electrodes being made by means of a coaxial line extending radially through an opening in the flow tube, the line having an outer conductor attached to the shielding electrode and an inner conductor attached to the detector electrode, the space between the line conductors being filled with the same dielectric material as that of the segment.

Unitized electrode assembly for electromagnetic flowmeter

An electromagnetic flowmeter system capable of measuring fluids having any degree of conductivity, including fluids having dielectric properties. The fluid to be measured is conducted through a dielectrically-lined flow tube to intersect a transverse magnetic field produced by an electromagnet, thereby inducing a voltage in a pair of planar electrodes mounted within the dielectric lining, each electrode being provided with a driven shield. The electromagnet is excited by a direct voltage which is periodically interrupted to produce a periodic steady state field whereby unwanted in-phase and quadrature components are minimized.

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Dransfeld, Germany

Eggert Appel