Oval Corporation

Oval Engineering Co., Ltd.

Shingo Gomi

Kenichi Matsuoka

Kimihiro Ichinose

Seiji Kobayashi

Takashi Endo

Yutaka Ogawa

Kazuhide Kobayashi

Osamu Futagawa

Hirokazu Kitami

Yuichi Nakao

Norio Sukemura

Katsuichi Uchida

Hidemi Seki

Toshio Seo

Nobuyoshi Umeda

Yuzirou Nagamori

Each of two flow tubes assumes an arcuate shape consisting of a central arcuate segment and two linear segments located on opposite sides of the central arcuate segment. The inside diameter of the flow tubes and the linear distance between end points of each of the flow tubes are determined on the basis of a target pressure loss arising from passage of a fluid to be measured through a manifold and the flow tube at the maximum flow rate, a target time phase difference between sine wave outputs from vibration sensors at the maximum flow rate, and a target natural frequency of the flow tubes. The length of the linear segments is selected so as to reduce thermal stress induced from an abrupt change in the temperature of the fluid to be measured, and the shape of the flow tubes is determined so as to reduce the vertical height of the flow tubes, so long as the thermal stress is substantially constant even when the length of the linear segments is varied. Thus, the shape of the flow tubes is determined in such a manner as to suppress, to a predetermined low value, stress arising upon abrupt change in the temperature of the fluid to be measured and as to be most compact.

Arch-shaped tube type coriolis meter and method for determining shape of the coriolis meter

A double-tube type Coriolis flow meter is provided for measuring mass flow. The flow meter includes a straight flow tube ( ) through which the fluid being measured flows, a hollow outer tube ( ) secured at both ends thereof to act as a counterbalance, a drive unit ( ), and a pair of sensors. The flow tube ( ) is caused to vibrate by the drive unit ( ) so that the mass flow of the fluid is measured by detecting a phase difference proportional to Coriolis force acting on the flow tube ( ) by the sensors. Sheet members (coupling plates ) secure the flow tube ( ) to both ends of the outer tube ( ) and integrally form the coupling plate ( ) with tube-assembly supporting leaf springs ( ) in the double-tube type Coriolis flow meter. By connecting the flow tube to the outer tube via the sheet members in this manner, stresses produced between the tubes are absorbed and a uniform temperature distribution is maintained in the outer tube and manufacturing costs are reduced.

Straight double-tube type coriolis flow meter

A resonantly drivable straight tube type Coriolis flowmeter which is capable of correcting instrumental errors caused by a change in density and temperature of measurable fluid. A coaxial double tube body that is composed of an inner tube wherein fluid to be measured flows and an outer tube with a balance weight attached thereto for equalizing natural frequencies of the inner and outer tubes is driven at a resonant frequency having a constant amplitude. A change of fluid density causes a change of amplitude ratio of the inner tube and the outer tube, resulting in shifting of an instrumental error. At this time, a resonant frequency detecting circuit detects a resonant frequency without detecting the amplitude ratio. An instrumental error detecting circuit stores a relation between resonant frequencies and fluid densities and a relation between fluid densities and instrument errors and conducts correction of an instrumental error according to the detected resonant frequency. An instrumental error caused by thermal deformation of the inner tube and the outer tube which are different from each other in material and shape can be also corrected by using similar correcting means.

Error correcting Coriolis flowmeter

Disclosed is a Coriolis flowmeter which is capable of detecting a mass flow and a density of fluid with an increased stability by resonantly oscillating a double tube portion consisting of an inner flow tube allowing fluid to flow therein and a coaxially disposed thereon counterbalance tube provided with a weight for equalizing the lateral natural frequency of the counterbalance tube with that of the flow tube. The Coriolis flowmeter has supporting metal means for supporting the both ends of the flow tube in such a way that the both ends of the flow tube is restricted in radial directions and axially movable in respective connecting flange; the inner flow tube has extending ends enlarged in diameter and supported in the respective connecting flanges of the outer housing. The flow tube is further supported at near-to-end portions on respective rectangle leaf springs having a plane parallel to oscillating direction and extending in radial direction of the double tube portion being perpendicular to the oscillating direction within the outer housing. The flow tube is thus supported at four stable points representing oscillating nodes, axially movable but radially restricted, assuring stable oscillation and accurate measurement of mass flow.

Coaxial double tube type Coriolis flowmeter

A Coriolis flowmeter of double conduit type having inner and outer conduits, is capable of effectively detecting with increased stability a Coriolis force acting on the inner fluid passage without being effected by external vibration, e.g., of piping, piping stress and a change of ambient temperature and the like. A cylindrical housing 33, connected with flanges 31 and 32 to flow piping, has a thick-walled cylindrical body 33a and end portions 33b each having a center bore 32c communicating with a cavity formed in the housing 33. The housing 33 accommodates an inner conduit 35 and an outer conduit 34 mounted coaxially with each other and secured each at both ends to the opposite end portions 33b. A vibrator 36 and sensors 37 and 38 are mounted between the inner conduit 35 and the outer conduit 34 that is equipped with an adjusting balancer 39 to obtain a resonant frequency of the same natural vibrations of the two conduits.

Coriolis flowmeter with natural frequency adjusting means engaged with

A small volume prover is disclosed which is compact and capable of obtaining highly reliable measurement, keeping a highly accurate base volume without being affected by temperature and pressure of fluid to be measured. The prover includes a cylindrical outer housing having a fluid inlet and a fluid outlet spaced apart from each other, a cylindrical measuring conduit having both open ends and first and second sets of fluid ports radially made in a wall thereof and coaxially mounted within the outer housing and an annular wall mounted between the outer housing and the measuring conduit at the position between the measuring conduit open end and the first set of ports thereof to form an upstream annular passage and a downstream annular passage. During proving preparation a piston is restrained by a piston actuator provided in the outlet-side end of the outer housing to permit the fluid to pass through the annular passage. At the time of measurement start, the piston is released to run and a valve actuator provided at the inlet side acts as a slide valve to closed the first sets of fluid holes.

Small volume prover

Growing community of inventors

Tokyo, Japan

Shingo Gomi