What is a Vortex Flow Meter?
What is a Vortex Flow Meter?
Measuring moving parts can be tricky, and you may end up with the wrong results if you don’t have the right tool used in this process. That is where a vortex flowmeter comes in. A vortex flow meter is a measuring device used to measure the flow of movement. You can get a vortex flow meter in brass, industrial grade, or plastic construction. When you compare a vortex flowmeter to other types of flow meters, you will see that the measuring process has low sensitivity variations.
The vortex shedding principle is used in the vortex flowmeter. This occurs when fluid such as water flows past a bluff body, creating vortexes. This means that the body is not streamlined. The size and the shape of the body will tell the frequency in which the vortexes are shed. It is a great tool to use when you want to reduce the cost of maintenance. In industrial-grade vortex meters, to get the proper sizing for different meters, vortex flowmeters are custom built.
The History of Vortex-Shedding
The first person to come up with the vortex shedding theory was a Hungarian-American physicist called Theodore von Karman. This is the effect created when a bluff body or a non-streamlined object is placed in the path of a fast-flowing stream. This forms eddies, which are vortices caused when the fluid separates from the bluff body. The action makes the boundary layer to detach and curl back while the fluid separates on its two downstream sides.
The fluid pressure goes down while the velocity goes up as the vortex is formed on the bluff body. The vortex strengthens and grows in size while it moves downstream. This causes it to shed or detach itself. Vortexes forming on the other side of the non-streamlined object is what follows. Vortices that alternate are placed at the same distances.
Key Elements to Observe When Picking a Vortex Flow Meter
- The type of fluid you want to measure
- The min and max pressure
- The range of the flow rate
- The temperature of the fluid
- The density ranges of the fluid
- The range of the velocity
- The size of the pipe
- The max drop of pressure that is acceptable
- The thickness of the wall or pipe schedule
- The material used to make the pipe
- The closest obstruction upstream
Vortex Flow Meter Styles
When using a smart vortex flowmeter, you will get more than the flow rate info from the digital output signal. That’s because smart vortex flowmeters have microprocessors in the flow meter, which correct errors in the straight pipes. When the Reynolds number drops below 10,000, the K-factor and the thermal expansion of the bluff body changes. This is the difference between the mating pipe and the bore diameter.
Diagnostic subroutines give smart transmitters that signal failure in the system. In case of any problem, testing routines are started by smart transmitters to find it. This applies to both the application and the vortex flowmeter. In ISO 9000 verification, these tests also come in handy.
There are other styles of vortex flowmeters capable of detecting mass flow. Vortex flow meters that are made this way can measure both the vortex pulse strength and vortex frequency at the same time. The readings that come from these meters can establish the density of the process fluid, and with a span of 2%, one can get the mass flow results.
Other vortex flow meters come with many sensors that are used to show the pressure of the process fluid, the vortex frequency, and the temperature of the fluid as well. This type of design reveals both the mass flow rate and density, based on the data given. For gasses and steam, the accuracy rate is 2%, while the mass flow in liquids the rate of accuracy is 1.25%. This vortex flow meter offers a cheaper option when you want to know the pressure and temp of the fluid. It means that you won’t need to install other transmitters.
Accuracy & Rangeability
The rangeability of the vortex flowmeter is affected when the velocity rises. This is due to the drop in the Reynolds number. The allowable accuracy and rangeability are between 8 and 30 centipoises of the max viscosity limit. For low-viscosity liquid applications, one can have a rangeability of over 10:1 and 20:1 for gas if the size of the vortex flowmeter is done properly for the application.
When Reynolds numbers go beyond 30,000, the inaccuracy rate of most vortex flow meters reaches 0.5-1%. The metering error increases as the Reynolds number drops. The actual flow error can go up to 10% when the Reynolds number is less than 10,000.
Vortex Flow Meter for Corrosive Liquids
When using corrosive liquids in a bluff body, a corrosion-resistant enclosure is used to house all electronics. Contaminated or corrosive fluids work well with plastic vortex flow meters than meters that have metal or moving parts. Applications range from highly corrosive slurries to ultra-pure water.
Industrial Grade Vortex Flow Meters
These types of vortex flow meters are used to measure gas, low-velocity liquids, and steam. Flowing fluids that create vortices stress the shedder bar in pulses. The shedder bar then transmits the pulses to the sensor.
Wedge Flow Meters
These types of vortex flowmeters give limits that are simple and reliable. The sensing flow is related to the pressure differential. Users can install these meters in full pipes orientation, including vertical, horizontal, or inverted. These meters are also built to support a process in a water application due to its compact and rugged design, that offers a range of calibration.
Vortex Shedding Flow Meters
These kinds of vortex flowmeters use the vortex shedding measuring principle. They are used with brass, FKM, and PVDF to measure clean, viscous, and dirty water-like fluids. Most processing industries use these applications, including power, rubber, steel, food, paper, and chemical. Flammable liquids or gasses like air won’t work well with these vortex flow meters.
As you can see, vortex flow meters are tools used in various sectors that use fluids and gases. They are perfect for measuring flow in bluff bodies or objects that are non-streamlined. That concludes our article about the obsession people has over vortex flow meters. We trust that you have found our article informative.
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