Understanding Coriolis Flow Measurement

Thompson Equipment
Coriolis flowmeters directly measure the mass flow of a subject fluid, which is inclusive of regular and supercritical liquids and liquefied gases. Operating on the Coriolis effect principle, Coriolis flowmeters create a controlled condition in which the mass flow of the fluid can be directly measured. They rely on motion mechanics: one or two tubes are aligned inside a Coriolis flowmeter, then made to oscillate with an exciter. Fluid flows through the oscillating tubes, twisting them slightly in proportion to the mass flow of the fluid and its inertia. There are highly reactive sensors attached to the tubes; when the measured substance flows through the vibrating tubes, the numeric difference between sensor readings provide the basis of the resulting fluid is mass flow measurement. This process also delivers a second measurement: the density of the substance. The sensors measure the frequency of oscillations. Coriolis flowmeters rely on direct computation instead of an algorithm, and therefore are regarded as highly accurate instruments in industry, coming in at 0.1 percent accuracy in some cases.
Coriolis principles
Rotation without mass flow
(image courtesy of Wikipedia).
Coriolis principles
Rotation with mass flow
(image courtesy of Wikipedia).
Coriolis flowmeters are advantageous choices for many industrial applications. They are used to measure drinking water, oils and gases, chemicals, etc. However, these mass flow measurement products particularly stand out in the chemical industry. As a prerequisite for most fluid processing operations, measurements and quantities often rely upon mass instead of upon volume. Coriolis flowmeters, with their direct measurement of mass flow, can be the optimal choice for applications requiring mass flow measurement.

As beneficial as Coriolis flowmeters are, they are not immune to some engineering and practical limitations. The most recognized limitation is the size of the pipes the meters are able to accommodate. A Coriolis meter is comparatively large, when other measurement instrument technologies are considered, making it difficult to place in some installations. In addition to being recognized as one of the most accurate flow measuring technologies, the Coriolis flowmeter requires little maintenance.
Coriolis principles
The vibration pattern with mass flow
(image courtesy of Wikipedia).
The vibration pattern during no-flow
(image courtesy of Wikipedia).

Selecting and configuring the instrument properly and assuring that installation is performed in accordance with manufacturer instructions are necessary tasks to achieving best instrument performance. Reach out to an instrumentation specialist with your flow measurement challenges, combining your process knowledge with their product application expertise to develop effective solutions.

For additional information on any industrial flow measuring technologies visit Thompson Equipment (TECO) at  http://www.teco-inc.com or call 800-528-8997.