Balance bar for a Coriolis flowmeter

Abstract

A balance bar for a straight tube Coriolis flowmeter. The balance bar is preferably manufactured by process that provides an increased number of flowmeter elements integral to the balance bar. These integral elements comprise: brace bars at each end of the balance bar, rib elements on each side of the balance bar to raise the lateral vibration frequency, a surface to facilitate the mounting of a driver to the balance bar and to a flow tube surrounded by the balance bar, surfaces to facilitate the mounting of sensors to the balance bar and flow tube, voids that lower the resonant frequency of the balance bar in the drive mode as well as in the second bending mode. An integral mass makes the vibration amplitude of the balance bar less than that of the flow tube. Said element that lowers the resonant frequency of the balance bar in the second bending mode also makes the flowmeter calibration factor independent of density. The balance bar is ideally made by a casting process in which the entirety of the balance bar is formed, but it may be fabricated by any process, including machining, that produces a flowmeter having some or all of the above mentioned elements integral thereto.

Description

technical field [0001] The invention relates to a Coriolis flowmeter, in particular to a balance bar for the Coriolis flowmeter. The invention also relates to a method for manufacturing a balance bar of a single-tube Coriolis flowmeter. Background technique [0002] A Coriolis flowmeter is characterized by a flow tube that is caused to vibrate at its resonant frequency as material flows through the flow tube. Every point on the flow tube vibrates in phase with every other point on the flow tube when no material is flowing through it. Two sensors (usually velocity sensors) located at different points on the flow tube produce sinusoidal signals that are in phase when no material is flowing through them, and are in phase when material is flowing through them. The generated sinusoidal signals have a phase difference. This phase difference is created by the Coriolis force produced by the material flowing through the vibrating flow tube. The magnitude of the phase difference b...

AI Technical Summary

Problems solved by technology

If any of the four brazed or welded joints are faulty or cracked, flowmeter performance and reliability will be reduced

There is also the problem that there are four junctions in one important region

[0009] It can thus be seen that the use of a cylindrical element as a balance bar in a single-tube Coriolis flowmeter produces the following problems, namely, reduction of the resonant frequency of the balance bar, reduction of lateral vibration of the balance bar, driver and sensor Mounting of the coils on the balance bar and the need for a separate support bar to connect the ends of the balance bar to the flow tubes

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