Vortex Flow Meter Principles of Operation

In yesterday’s post, we looked at three different flow measurement technologies used in fiscal metering applications—differential pressure (DP), Coriolis, and Ultrasonic.

Today let’s look at flow measurement with vortex flow meters. There is a new, very educational video on the Rosemount YouTube channel, Introduction to Vortex Flow Meter Technology. This 4:49 video explains the basic principles of operation behind vortex flow meters and how they are used to accurately measure liquids, gasses and steam using a principle known as the von Kármán effect.

The video opens noting some of the advantages of vortex flow measurement technology including easy installation without impulse lines, no moving parts to maintain our repair, less leak potential, and a wide flow turndown range.

The video shows the key parts of a vortex flowmeter—meter body connected into the piping, a sensor to sense the vortices coming off the internal obstruction or shedder bar, and the transmitter to bring the volumetric flow information back to the control system. The shedder bar causes process fluid to separate and form areas of alternating differential pressure known as vortices around the backside of the shedder bar.

These vortices then cause a small sensing element to oscillate back and forth at a specific frequency. The velocity of the fluid is directly proportional to the frequency of the vortices. Using the known cross-sectional area of the pipe, volumetric flow is calculated.

The transmitter picks up the signals from the vortex sensors and applies the calculations to turn these signals into a flow rate which can be displayed locally at the transmitter and back at the control system. Applications include liquids, gases and steam. They are suitable for high process temperatures and pressures.

Rosemount multivariable vortex flow meters combines temperature and flow devices into a single instrument and automatically adjusts for changes in density, making it easy to accurately measure mass and corrected volume in steam and liquid applications. They are especially effective in saturated and superheated steam applications as well as liquids approaching saturation point.

Watch the video for more on how vortex technology addresses low flow cutoffs and minimum measurable flows as well as how dual and quad vortex flowmeter arrangements can be used in safety instrumented system loops. The Flow Solutions Technology Advisor site is excellent for helping you find the right flow measurement technology for your application.

You can also connect and interact with flow measurement experts across many technologies in the Flow group of the Emerson Exchange 365 community.

Posted Friday, January 20th, 2017 under Education, Flow.