Exac Corporation

Other

Erik B Dahlin

Alan M Young

Andrew K Levien

Sidney V Kaiser

A Coriolis mass flow rate measuring apparatus including one or more detecting means (46), (48), (56) for detecting conduit detection portion velocities caused by Coriolis forces exerted by a mass flowing through the oscillating conduit, and means (54) operative to measure the time differences between said first and second points in time when respective velocity signals have zero velocity and to use such measurements according to the formula ##EQU1## to indicate the mass flow rate.

Apparatus for mass flow rate and density measurement

A Coriolis-type mass flowmeter in which the flow tube is vibrated at a resonance frequency approximately equal to the frequency for forced or natural vibration in a higher anti-symmetric mode, such as the second mode. In the preferred embodiment the flowmeter is symmetrical and has sections of oval cross-section that provide low bending resistance to the vibration at the points where the amplitude of vibration is the largest. The preferred embodiment uses electronic signal detection/processing means that generates two signals proportional to flow tube velocity in the direction of vibration of equal distance but on opposite sides of the plane of symmetry of the tube, generates a sum and a difference of the two signals, integrates the sum, demodulates the integrated signal and the difference of the two signals to produce peak amplitude signals, and divides the peak amplitude signals to produce an output that is proportional to mass flow rate. The preferred embodiment is further equipped with a novel acoustic wave suppressor, including a bypass conduit and a flexible diaphragm mounted within the flow tube, which suppresses acoustic waves by transmitting them across the diaphragm, thus isolating the flowmeter from the acoustic waves.

Acoustic wave supressor for Coriolis flow meter

A fluid meter, such as a density meter or a Coriolis-type mass flow meter is disclosed in which the fluid tube is mounted to allow for expansion and contraction relative to a base to which opposite ends of the tube are mounted. In the preferred embodiments, a single, rectilinear flow tube measuring section is bounded at each end by a thermally insulating wall having a linear bearing which allows longitudinal axial movement while restraining transverse movement. Disposed distally of the linear bearing relative to the flow tube measuring section is means for accommodating the expansion and contraction of the measuring section. In one embodiment this is in the form of a laterally coiled tube portion. In a serial double-tube flow sensor, three serial rectilinear and parallel sections of the flow tube pass through linear bearings similar to that of the single tube, with arcuate sections joining adjacent rectilinear sections. In a third embodiment, the flow is split into two parallel tubes, one end is mounted to the base or housing by a compressible section and the other end is fixedly mounted directly to the base. The two parallel rectilinear measuring sections pass through linear bearings subsequent to the inlet flow splitter and prior to the outlet flow combiner.

Fluid measurement apparatus providing flow tube strain relief

A Coriolis mass flow rate measuring apparatus including at least one helically configured loop (30) of conduit, a drive mechanism (42) for causing oscillatory movement of a portion of the loop in a direction normal to the direction of flow through the conduit portion and generally parallel to the central axis of the loop, and one or more detectors (46), (48), (56) for detecting the motion resulting from the Coroilis forces exerted on other portions of the loop as a result of the mass flow therethrough and the oscillatory translation thereof. A strain gage (208) and associated processing electronics are also used in combination with the mass flow rate information to determine the density of the flow.

A Coriolis mass flow rate measuring apparatus including at least one elongated and helically configured loop 30 of conduit, a drive mechanism 42 for causing oscillatory movement of a portion of the loop in a direction approximately normal to the direction of flow through the conduit portion and approximately parallel to the central axis of the loop, and one or more detectors 46, 48, 56 for detecting the resulting motion caused by the Coriolis forces exerted on other portions of the loop as a result of the mass flow therethrough and the oscillatory translation thereof.

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San Jose, CA, United States of America

Erik B Dahlin