Blog: Another look at the Coriolis principle of operation

By Jesse Yoder

For many years, I’ve questioned why Coriolis flowmeters are called “Coriolis” meters. In 2011, I even wrote an article for Flow Control, The Coriolis Effect, arguing they should be called “inertial mass meters,” and discussing whether they embody the Coriolis principle.

I’ve discussed this with the top engineers and designers at the leading Coriolis companies in the US, UK, and Switzerland. I have even had discussions with colleagues from Germany who have spent 25 years designing these meters. These are the main points discussed.

1. It is believed that Coriolis meters employ a force that governs the behavior of bodies in a rotational frame of reference. This is sometimes called a Coriolis force.
2. Coriolis meters do not employ the “Coriolis effect,” which has to do with the observed deflection of a body moving over a rotating platform. This is what Gustave Coriolis was referring to when he wrote about storms being deflected as they move north from the equator.
3. Once you remove the Coriolis effect from the equation, there is no longer any reason to call the meters “Coriolis” meters. Perhaps “oscillating meters” would be more accurate.

This is something I’ve struggled with for over 10 years and now at last, I see a solution!

To clarify, Coriolis meters are the most accurate meter made and they solve a lot of flow problems that other meters don’t. I’m not saying we should change their name. I am saying that Coriolis meters don’t make use of the Coriolis effect.

This has been dubbed a “Coriolis force” by people like Yao Tzu Li who patented an early version of this meter in 1960 and by Anatole Sipin who has three patents in the 1960s. This terminology was picked up by dozens of later patents. The problem is that Gustave Coriolis was talking about a “fictitious” force that was described after his death (1843) as the Coriolis effect. It refers to the apparent effect on the motion of an object passing over a rotating frame of reference when viewed from the perspective pf the point of origin that moving object. The force exerted by the oscillating tubes of a Coriolis meter on the fluid is a real force, but it is due to the fluid movement along a small portion of a circle. It is unrelated to Gustave’s Coriolis effect.

For more information on Coriolis flowmeters, see New-Technology Flowmeters a new book from CRC press, available at New-Technology Flowmeters, Yoder, Jesse, eBook – Amazon.com.