A vortex flow meter is an instrument that measures and controls the flow of liquids, steam, and gas where there is a problem with moving parts. These devices come in industrial grade, and the material can be brass or plastic.
How does Vortex Meter work?
These flow meters operate under the vortex shedding principle. An oscillating vortex or a whirlpool of fluid occurs when water flows past a bluff body. This frequency of vortex shedding depends on the size and shape of the body. Vortex meters for industrial use are custom built and must have correct sizing for specific applications.
Let’s see how a vortex flowmeter works and why it’s perfect for industrial flow applications such as gas, liquid, and steam.
Vortex meters use a shedder bar to generate a repeating pattern of swirling vortex, a phenomenon known as von Kármán vortex street. It might use various sensor technologies to convert these oscillating vortices into a digital signal. And the processing happens in the meter’s electronics for flow calculation.
Vortex Flow Meters Styles
Some vortex meters provide an output signal with more information than flow rate. And because of the microprocessor inside the flowmeter, this automatically corrects insufficient straight pipe conditions. That includes the differences between the bore diameter and the mating pipe. A thermal expansion of the bluff body and K-factor immediately changes the Reynolds number below 10,000.
Vortex Flow Meter (Corrosive Liquids)
The plastic vortex meter is ideal for aggressive fluids. And place the electronics with no moving parts in a corrosion-resistant enclosure. So, these use applications with ultra-pure water, slurries, and highly corrosive chemicals.
Industrial Vortex Flow Meter
These measure various liquids with low viscosity, steam, and gas. After the flowing fluid sheds the vortices, this stresses the shedder bar in pulses, and then it transmits the stressed pulses to the encapsulated piezoelectric sensor.
Vortex Shedding Flow Meter
This style of vortex flowmeter operates on the same principle of the vortex shedding measurement. And it’s suitable for clean, viscous, and dirty liquids or particles. But they have to be compatible with PVDF, brass, or FKM. Most of these applications are in process industries, manufacturing, paper, rubber, steel, refining, fabrication, chemical, food, and petrochemical. However, they are not suitable for flammable liquids or air gases.
Some vortex flowmeters can simultaneously measure mass flow, pulse strength, and frequency. And from these readings, you can determine the density of the process fluid and calculate the mass flow within 2 percent of the span.
The meter provides a less costly alternative to separate transmitter installations and is convenient. Also, other designs have multiple sensors that detect the process fluid’s vortex frequency, temperature, and pressure. The data provided then determines the density and the mass flow rate. These flow meters give a 1.25 percent rate accuracy when measuring the liquid flow mass. And when measuring gasses and steam, it provides a 2 percent rate accuracy.
Installation Recommendations
Vortex Meter Installation
The vortex meter installation must be free from swirls or distortions. So, it should have a well-done symmetrical flow velocity profile. And to condition the flow, it necessitates the use of straight up-and downstream piping.
You can install the meters vertically, horizontally, or at any other angle, ensuring that you have kept them flooded. Ensure the straight length of the pipe and the meter are the exact sizes required for a beta ratio of 0.7 orifice installation. Most manufacturers recommend 30 pipe-diameters as a minimum downstream of control valves. And between the meter and downstream pressure taps, 3 to 4 pipe diameters. These must be small and placed 5 to 6 diameters downstream for temperature elements.
In Conclusion
This is how vortex flow meters work using the von Kármán effect. It states that; there will be a repeating pattern of swirling vortices as the flow passes by a bluff body.
These devices work best for applications requiring low maintenance costs. And they are also ideal for extensive facilities where the measurement of saturated and supersaturated steam is required to improve allocation and steam production efficiency.
