A vortex flow meter measures flow by placing a strategic obstruction, called a bluff body, in the path of a flowing liquid, gas, or steam. Vortices form on either side of it and break away in an alternating pattern, and the frequency of the pressure pulsations they create is directly proportional to the flow rate.
Key Takeaways
- A sensing element behind the bluff body picks up the pressure shifts, amplifies the signal, and converts it to a 4-20 mA output.
- Insertion vortex flow meters are an ideal solution for larger pipes, where inline installations are not cost effective.
- Multivariable vortex flow meters add temperature and pressure measurement to deliver a mass flow rate for gases, liquids, or steam.
- With no moving parts to wear, vortex flow meters offer longevity of service and need minimal maintenance for clean media.
- Vortex flow meters are not suited to high viscosity media, slurries, media that coats or crystallizes, or pulsating flow.
How Do Vortex Flow Meters Work?
Vortex flow meters work by placing a strategic obstruction in the path of the flowing media. This obstruction is commonly called a bluff body. As the gas or liquid passes by, vortices are created. They form on either side and break away in an alternating pattern.
A good example of this type of behavior in everyday life is a flag that is attached to a flagpole. As the flowing wind contacts the flagpole, the flagpole itself creates the obstruction that causes the flag to billow in the wind in an alternating wave. Another example is a rock in the middle of a river. It is plain to see, via the eddy behind the rock and the subsequent flow, that vortices are being created by the rock.
In the formed vortices, pressure decreases when a vortex is formed and increases when it is shed. This is true on both sides of the bluff body and causes pressure pulsations. The frequency of the pressure pulsations is directly proportional to the flow rate. A sensing element picks up the shifts from side to side behind the bluff body, amplifies the signal, and converts it to a 4-20 mA signal.
Vortex Shedding Flow Meter
Vortex shedding flow meters come in a variety of line sizes, connections, material builds, and installation options. There are different models that are suitable for a wide variety of media including liquids, gases, and steam. Certain models also offer multi-variable capabilities. They all operate on the same principle of the bluff body obstruction into the flow stream.
KOBOLD's DVZ is one example of an inline vortex shedding flow meter.
What Are Insertion Vortex Flow Meters?
Insertion vortex flow meters are an ideal solution for vortex flow measurement in larger pipes, where inline installations are not cost effective. They reduce installation costs and are installed by creating a hole in the process pipe with a connection, then inserting the probe into the hole via the connection on the flow meter.
For insertion vortex flow meters, the probe should be inserted into the highest velocity part of the flow stream in the pipe. KOBOLD's DVE insertion meter works with liquids, gas, or steam, and is also a multi-variable flow meter.
What Are Multivariable Vortex Flow Meters?
Multi-variable vortex flow meters do not just measure the flow rate. They also employ temperature and pressure measurement to deliver a mass flow rate for gases, liquids, or steam. Because so many process parameters are being measured at one exact point in the process line, they can deliver a much more accurate measurement than straight flow meters.
Having three different types of measurement in one instrument saves money and decreases the complexity of installation and maintenance. KOBOLD carries the DVE Insertion Multi-Variable Vortex Flow Meter and the DVH Multi-Variable Flow Meter with inline installation capabilities through ANSI Flanged or Wafer-Types.
What are some Applications for Vortex Flow Meters?
Common applications for vortex flow meters include:
- Food & Beverage
- Chemical & Petrochemical
- Energy Industries
- Metallurgy
- Pharmaceuticals
- Oils & Fuels
- Steam Measurement
What Media Can Vortex Flow Meters Measure?
Vortex flow meters can measure a range of media, including:
- Water, Chilled or Hot
- Ultra-pure Water
- De-ionized Water
- Glycol Mixtures
- Solvents & Acids
What are the Advantages of Vortex Flow Meters?
Vortex flow meters are versatile, reliable, and accurate, with no moving parts to wear. Their advantages include:
- Versatile: for gas, liquids, or steam
- Low to medium initial set-up cost
- Minimal maintenance for clean media
- Reliable and accurate
- Longevity of service, no moving parts to wear
- Can be installed at any angle if the bluff body is submerged
- Do not require impulse line heat tracing like DP orifice meters do
- Low to medium pressure loss
What are the Disadvantages and Limitations of Vortex Flow Meters?
Vortex flow meters have these disadvantages and limitations:
- Not for high viscosity media or slurries
- Not for media that coats or crystallizes
- Strainers and filters may be necessary
- Not great accuracy for really high or really low velocity flow rates
- Not suitable for pulsating flow
- Straight pipe requirements can be high, especially for insertion models
- Does not work well with vibration
- Not generally suitable for applications requiring batching capabilities
Vortex Flow Meter Manufacturers
KOBOLD Instruments has been manufacturing vortex flow meters for decades. We offer both insertion and inline models as well as multi-variable vortex flow meters. We also offer a completely unique flow meter technology that is very similar to vortex flow meters. Model DOG is built especially for wet gas flow measurement and has a simple and reliable gravity-fed method to drain any liquid condensate.
To learn more about this unique technology, view our DOG Oscillation Flow Meter product page. To see all of our vortex flow meters, visit our vortex flow meter product page.
Learn more about why you should partner with KOBOLD for your application.
Frequently Asked Questions
The bluff body is the deliberate obstruction that sits directly in the flowing media's path. As gas or liquid moves around it, vortices build up on both sides and peel away one side at a time. Every vortex shedding model, inline or insertion, relies on this same obstruction in the flow stream.
A vortex flow meter provides a 4-20 mA signal. Its sensing element detects the side-to-side pressure shifts behind the bluff body, then amplifies and converts them. Because the pulsation frequency rises and falls in direct proportion to flow rate, the output follows the flow.
Yes. Vortex shedding meters come in models suited to liquids, gases, and steam, and steam measurement is one of their applications. Multivariable versions go further, adding temperature and pressure readings so they can report a mass flow rate for steam, gases, or liquids. KOBOLD's DVE and DVH are both multivariable models.
Yes, provided the bluff body stays fully submerged in the media. Orientation is otherwise flexible, but a few other installation points matter: straight pipe needs can run high, particularly with insertion models, and strainers or filters may be needed. For insertion meters, the probe goes where the flow stream moves fastest.
No. Vortex flow meters are not meant for slurries or high-viscosity media, and should not be used with media that coats or crystallizes. They are also unsuitable for pulsating flow, lose accuracy at very high or very low velocity flow rates, and are generally a poor fit for batching applications.
A multivariable meter measures flow, temperature, and pressure at a single exact point in the process, which lets it give a much more accurate reading than stand-alone flow meters. Combining three measurements in a single instrument also saves money and makes installation and maintenance simpler.
No. Vortex flow meters have no moving parts to wear out, which gives them a long service life. Maintenance stays minimal when the media is clean, their up-front set-up cost is low to medium, and so is their pressure loss. Unlike DP orifice meters, they also skip impulse line heat tracing.
Yes. KOBOLD's Model DOG uses a flow meter technology closely related to vortex measurement, and it was designed specifically for wet gas. A simple, reliable gravity-fed design drains any liquid condensate that collects. The DOG is an oscillation flow meter, offered alongside KOBOLD's insertion, inline, and multivariable vortex models.
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