Rosemount Inc.

David C Bohn

David Lyle Wehrs

Darroll D Bengtson

Lloyd E Graupmann

Kevin R Ley

Jean P Murray

A process variable transmitter providing a transmitter output representing a process variable sensed by a sensor. The transmitter has a filter with a bandwidth which is automatically adjusted based on noise detected in a sensor output. When the transmitter senses higher sensor noise levels, it automatically decreases the bandwidth to damp noise in the transmitter output. When the transmitter senses lower sensor noise levels, it automatically increases the bandwidth to provide faster response to changes in the process variable.

Adjustable bandwidth filter for process variable transmitter

A flow tube of a ceramic material used for a magnetic flowmeter is formed to have regions of a ceramic material which has enhanced properties useful in magnetic flowmeters, such as enhanced electrical conductivity or enhanced magnetic permeability. The ceramic material having enhanced electrical conductivity is used to form sensing surfaces directly in the flow tube wall so that there is no need to have separate metal electrodes attached to or otherwise formed in the wall of the flow tube. This insures a strong, monolithic flow tube wall.

Flow tube for a magnetic flowmeter

A travelling wave magnetic flowmeter senses the velocity of flow of an electrically conductive fluid through a conduit and provides an output signal representative of the velocity of flow. A first pair of coils providing a first magnetic field and a second pair of coils providing a second magnetic field are disposed on the conduit. The first and second magnetic fields are varied in strength and at least partially combined to form a travelling composite magnetic field, a portion of which interacts with the fluid to induce an electromotive force. A pair of electrodes are electrically isolated from the conduit and disposed in the conduit between the first and second coils. The electrodes are electrically coupled to the fluid to provide a detected signal representative of the electromotive force. A control circuit coupled to the first and second coils and coupled to the electrodes to receive the detected signal, controls an electrical current shifted between the first coils and the second coils such that the travelling composite magnetic field travels in the direction of fluid flow at a speed representative of the fluid velocity.

Travelling wave flowmeter

An electromagnetic flowmeter for measuring the flow of an electrically conductive fluid through a flow system comprises a flow tube adapted to be connected in the flow system for allowing the fluid to flow therethrough. Coils supported by the flow tube are energized to provide magnetomotive force to produce a magnetic field, a portion of which interacts with the fluid to produce an electric field within the fluid. Electrodes supported by the flow tube receive signals from the electric field representative of flow. The electrodes are coupled to a signal processing circuit which processes the signals and transmits an output signal representative of flow to suitable readout equipment. At least one magnetomotive force adjusting means, such as a plurality of coil taps or connections that permit changing the number of energized turns in the coils allow selection of a desired magnitude of magnetomotive force to set the magnitude of the magnetic field such that signal variations resulting from manufacturing tolerances of the flow tube, coils and electrodes are substantially compensated for and the signals received by the electrodes are compatible with a calibration range of the signal processing circuit.

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Eden Prairie, MN, United States of America

David C Bohn