Coriolis mass flow measuring principle

Instruments of the CORI-FLOW® series contain two parallel tube loops, forming part of an oscillating system. When a fluid flows through the tubes, Coriolis forces cause a variable phase shift between the loops, which is detected by sensors and fed into the integrally mounted pc-board. The resulting output signal is strictly proportional to the real mass flow rate, whereas thermal mass flow meters are dependent of the physical properties of the fluid. Coriolis mass flow measurement is fast and very accurate.

In the field of flow measurement, flow meters employing the Coriolis principle have recently become of primary interest in industry due to their ability to measure mass flow rate of fluid without an intrusive device in the flow stream. Coriolis type mass flow meters operate on the principle that fluent material passing through a conduit tubing, when exposed to a deflection or oscillation transverse to the direction of flow, will react with a measurable force (the Coriolis force) on the walls of the tubing. Coriolis mass flow meters typically comprise one or more geometrically precise flowtubes which are made of a strong yet resilient material such as stainless steel or titanium. The flowtube is mounted in a supporting structure having end connections, such as a casting or a pipe, to protect the flowtube and to provide for the attachment of the flowtube to external process piping. In a typical Coriolis mass flow measurement application, a conduit is excited at resonance in one of its natural vibrational modes as a material flows through the conduit, and motion of the conduit is measured at points along the conduit. Excitation is typically provided by an actuator that perturbs the conduit in a periodic fashion. There are two basic types of Coriolis mass flowmeters, one employing a more or less straight Coriolis measuring tube, the other a looped Coriolis measuring tube. As another differentiating feature, there are mass flowmeters with only one Coriolis measuring tube and those with two Coriolis measuring tubes, in the latter case permitting either parallel or in-line flow of the fluid. Coriolis mass flowmeters are available in various sizes and flow capacities to measure material flow and generate information such as mass flow rates, density, etc., pertaining to the material flow.

The Coriolis principle is not new to process flow measurement and control. It is a proven technology that has been employed in a wide variety of markets and applications for over 15 years. Although Coriolis has been widely used in high flow processes, the sensing and integrated control principle has only recently been taken to the low flow market.The Brooks QUANTIM™ family of Coriolis flow meters and controllers uses a proven direct mass flow measurement technology to provide precise flow measurement and control of liquids and gases. These Coriolis mass flow devices include an integrally mounted control valve in a compact miniaturized configuration. They can simultaneously measure mass flow, fluid density and temperature. QUANTIM Coriolis meters, controllers, and sensors provide unsurpassed performance, solving specific challenges in demanding low-flow applications.QUANTIM handles critical liquid and gas applications in flow ranges from 0.001-28 kg/hr.