Extracorporeal Medical Specialties Inc.

Parker Research Corporation

Richard A Morrow

Vernon H Troutner

A portable, battery-operated AC electromagnetic yoke for detecting surface defects in ferrous materials by employing an AC magnetic field. The yoke includes a circuit that produces a quasi AC square wave voltage. The resulting AC magnetic field is the required inspection method of common practice and is capable of demagnetizing upon completion of inspection. A first bank of batteries supplies approximately sixty volts positive DC and a second bank of batteries supplies approximately sixty volts negative DC to power transistors that are in electrical communication with the yoke. Logic circuitry is employed to switch the respective banks of batteries on and off to simulate an AC circuit. The logic circuit includes a clock for generating pulses that are fed to a phase splitter circuit and to a delay and pulse shaping circuit. The respective outputs of those circuits are fed to logic gates that are in electrical communication with a voltage level shifting circuit that triggers the power drivers. A plurality of power resistors in conjunction with the inductor in the yoke provides the proper time constant for the magnetizing current to reach a large enough value to provide sufficient magnetic force to detect the surface defects, demagnetize, and lift ten pounds of ferrous material.

Battery powered AC electromagnetic yoke for magnetic particle inspection

A hemodialysis system capable of operation in either a single needle mode or a double needle mode includes an arterial blood pump which is the sole blood pump in the system during the double needle mode. For single needle mode operation a venous blood pump is employed to return blood to the patient. A pump speed control adjusts the speed of the arterial pump in the double needle mode, and the speeds of both blood pumps in the single needle mode. A controller continuously operates the arterial pump in the double needle mode, and alternately activates the two pumps in the single needle mode. A module for modifying a commercially available double needle system for operation in either of the two modes is also described.

Dual mode hemodialysis system

Blood flowrate in a hemodialysis system is controlled in accordance with the relative speeds of two periodically operated blood pumps. Information as to the speeds of the two pumps is converted to flowrate information, which is used to determine the mean flowrate of blood through the system. The mean blood flowrate may be altered by changing the speeds of the blood pumps in a control system which maintains a constant ratio of pump speeds.

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Tarpon Springs, FL, United States of America

Richard A Morrow