Abstract: A Coriolis mass flowmeter comprising a vibration tube fixed to a housing at an upstream fixed point and a downstream fixed point and an original axis is taken as a straight line connecting these fixed points, wherein the vibration tube is operated so that the tube performs simple harmonic oscillation or circular motion on circumferences at predetermined distances away from each point on the original axis around the original axis take as a center. Since the vibration tube oscillates only in the circumferential planes at equal distances from the original axis, the length of the vibration tube does not vary regardless of the position of the tube. Thus, tensile force in the direction of the axis is always constant and leakage of vibration dued to variations in the force in the direction of the axis is eliminated. The enhanced isolation of vibration makes the vibration inside the flowmeter stable. Accordingly, a highly accurate and stable Coriolis mass flowmeter is achieved by the invention.

Abstract: An electromagnetic flow meter for measuring the flow rate of a fluid by applying to the fluid a magnetic field generated with an exciting current and measuring the resulting signal voltage generated at a pair of electrodes; wherein the exciting current comprises two frequency components which are lower and higher than the usual commercial frequency and the signal voltage comprises two frequencies which are discriminated so that a higher frequency is extracted as a first output and a lower frequency is extracted as a second output, through a low pass filter having a large time constant. A predetermined operation, such as addition, zero correction, response correction, etc, is carried out on the first and second outputs to produce a flow rate output. The invention has quick response, stable zero point and reduced susceptibility to noises.