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The "K-factor" of Coriolis Flow Meters
Micro Motion Chief Blogger
Total posts: 13
Joined: 5 year(s) ago
Posted 1:48 PM 2/3/2011
4.7/5 stars (3 votes)

Hi Community, I received the following question in a email from a person who found the Emerson Process Experts blog:



I'm doing some research on data acquisition of flow meters and am interested in the K-factor of turbine and PD type meters. In particular, I'm doing a comparative analysis of the response times of varying flow meter brands and technologies. There are certainly a wide range of K-factors depending on the brand and technology of the flow meter! As my research brought me to Coriolis meters, I seemed to run into a snag since the K-factor is tied to pulses per unit volume, which makes sense for moving parts, but is not the same for flow meter technologies with no moving parts, like Coriolis meters. Subsequently, a K-factor equivalent does not seem to be clearly highlighted in the many technical specifications of Coriolis meters I have reviewed, unless of course, I am looking in the wrong area.


I was curious, since I have not used Coriolis flow meters before, what would be the equivalent to the K-factor on Coriolis flow meters?


Does anyone have guidance they can share? Thanks!


Micro Motion Employee
Total posts: 76
Joined: 5 year(s) ago
Posted 11:00 AM 2/9/2011
3.7/5 stars (3 votes)

As the original emailer mentions, Coriolis flow meters do not have a K factor in the same sense that Turbine and other PD type meters do. But if you look at the K factor as a general concept, it can be described as a conversion factor. It converts the raw sensing data from the meter into a "useable" flow value. A Coriolis meter does have a factor that meets this decription. For Micro Motion it is called a Flow Calibration Factor or FCF.


The turbine meter K factor converts rotation of the turbine (and thus a fixed amount of volume). A Micro Motion FCF converts twisting of the flow path. The units for a Micro Motion FCF are grams/second/microsecond of phase shift. For example, an FCF of 10.000 means that for every 1 microsecond of phase shift in the Coriolis flow tubes, the mass flow rate is 10.00 grams/second.


Micro Motion has a very detailed tutorial on the operating principle of Coriolis mass flowmeters including a discussion on this Flow Calibration Factor. http://www.emersonprocess.com/micromotion/tutor/index.html

Micro Motion Chief Blogger
Total posts: 13
Joined: 5 year(s) ago
Posted 12:04 PM 2/9/2011
5/5 stars (1 vote)
Nathan, Thanks! I forwarded your answer and a link to this thread to the person who asked me the question.
Total posts: 10
Joined: 4 year(s) ago
Posted 11:22 PM 5/7/2011
4/5 stars (1 vote)
Hi I am working for Pemex Exploration in Mexico, the k-factor or the meter like displacement, turbine, ultrasonic or coriolis is used as explain API MPMS 4.8 for proving and calibrating meters, un custody transfer applications you have to controll the k-factor of your meter, and you need to prove-calibrate meter at 6 months o 1 year period, when the meters are used to load Tankers some times you need to prove-calibrate meters in each load.
Total posts: 2
Joined: 2 week(s) ago
Posted 4:28 AM 10/9/2014
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Does that mean you cannot change the K-factor on Custody Transfer Coriolis Meter on site? If I changed the K factor on site then will that void my calibration certificates and hence Custody Transfer NMI approval..

Moderator
Micro Motion OEM Technical / Sales Support Engineer
Total posts: 202
Joined: 4 year(s) ago
Posted 12:20 AM 10/13/2014
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Hi,
If the Custody Transfer Mode is enabled, you are not able to chance the configuration. In case the device is sealed, you can’t disable the “Custody Transfer Mode” without breaking the seal. In other words: Any change of the configuration needs to be approved by the service which is allowed to reseal the device.
Cheers Oliver