Fischer & Porter Company

Wilfried Kiene

Eggert Appel

Peter Nissen

Gottfried Geisler

Dieter Meier

Rudi Kuchemann

Herbert Gehrke

Device to measure the flowrate of a fluid flowing in a partially full line, such as a canal or open channel, with coils arranged above and below the partially full line to generate a magnetic field extending essentially vertically through the partially full line and with electrodes arranged opposite each other on opposite lateral walls of the partially full line. An excitation circuit excites the coils and an evaluation circuit processes the potential difference at the electrodes resulting from the magnetic field and the fluid flow to produce a flowrate proportional signal. The device is characterized by a bridge which spans the partially full line and on which the upper coil is positioned with the vertical axis of the upper coil extending through the central region of the bridge.

Device to measure the flowrate in a partially full line

A weir is placed across a pipe section and an electromagnetic flow meter with multiple electrodes is located upstream of the weir. The liquid level and velocity of fluid in the pipe section are evaluated by the electromagnetic flow meter to determine flow rate.

Electromagnetic flow meter with weir

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 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

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.

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Munden, Germany

Wilfried Kiene