A vortex flow meter is a flow measurement machine that introduces moving parts to present conditions. They come in a variety of materials, including industrial-grade, brass, and all-plastic.
Vortex flow works under the vortex shedding principle, where an oscillating vortex will occur the time the fluid-like water flows past a bluff body. The tendency that the vortexes are shed relies on the size and shape of the body. It is best for applications where low maintenance costs are essential. Industrial vortex meters are well-designed and require suitable sizing for certain applications. Continue reading this article and know several ways how the vortex flowmeter operates.
Vortex-Shedding History
Theodore von Karman was the first to explain the effect where a non-streamlined object placed in the path of a fast-flowing stream. This causes the fluid to differentiate the object on its two downstream sides appropriately. And, as the boundary layer becomes detached and turns back on itself, forming vortices. He also discovered that the distance within the vortices was constant and depended solely on the size of the rock which made it.
The fluid velocity is higher on the side of the streamline body that the vortex is made, but the pressure is lower. When the vortex moves downstream, it gains strength and size, then suddenly detaches or sheds itself. This is then followed by a vortex being made on the other side of the streamlined body. The alternating vortices are spaced at the exact distances.
Vortex Flow Meter Styles
Smart vortex meters give a digital output signal that has more information compared to the flow rate. The microprocessor in the flowmeter may automatically correct for straight pipe conditions. But for the differences between the bore diameter with that of the mating pipe. And also, for thermal expansion of the bluff body, the K-factor differs when the Reynolds number drops below 10,000.
The intelligent transmitters are also provided with diagnostic subroutines which signal components or other problems. Smart transmitters use to initiate testing routines to detect the problems with the meter and the application. These on-demand tests may also be helpful in ISO 9000 verification.
Other vortex flowmeters use to detect mass flow. One such design determines the vortex frequency and the vortex pulse strength accordingly. From these readings, the density of the method liquid can be determined with the mass flow evaluated within 2% of span.
Installation Recommendations
If you are installing a vortex flow in an existing method where the flow range is unknown, create some measurements using a portable pitot or a clamp-on ultrasonic machine. Although, there is no guarantee which shows that a line-size vortex meter will function at all.
The vortex meter needs a well-developed flow velocity profile, free from any distortions or swirls. This makes use of straight-up and downstream piping to design the flow. The straight length of the pipe should be the same size as the meter, and its length has to be the same as needed for an orifice installation with a beta ratio of 0.7.
Several vortex flowmeter manufacturers need a minimum of 30 pipe diameters downstream of control valves. And 3 to 4 pipe diameters within the meter with the downstream pressure taps. The temperature product has to be small and located 5 to 6 diameters downstream.
This meter can install vertically, horizontally, or at any angle, as long as they are kept flooded. The meter can be kept flooded by installing it in a vertical upward flow line. The downstream piping has to be kept elevated when you install the flowmeter in a downward or horizontal flow.
Check valves also can be useful to keep the piping full of fluid if there is no flow. Block and bypass valves will be needed when the replacement of the sensor in a certain shape needs the stopping of the flow with the opening up of the process.
Vortex Meter Advantages
- Vortex meters use for liquids, gases, and steam.
- It is relative to turbine flow meters.
- The vortex flowmeter has a minimal installation and maintenance cost.
- It is less sensitive to variations in process conditions.
- Stable long-term accuracy with repeatability.
- Useful for a wide range of process temperatures.
- It finds in a wide variety of pipe sizes.
Vortex Flow Meter Limitations
- Not useful for very low flow rates
- The minimum length of straight pipe needs upstream and downstream of the vortex meter.
Vortex Flow Meter Applications
Vortex flow meters are helpful for several applications and industries though they function best with clean, low-viscosity, medium to high-speed liquids. Other of the primary uses include:
- Used in the transfer of natural gas metering
- Steam measurement
- The flow of fluid suspensions
- In water applications
- Liquid chemicals & pharmaceuticals
Conclusion
From the shedding principle of the vortex flow, the main advantage of meters is that they have low sensitivity in the process conditions. Also, it is low wear relative to orifices or turbine meters. The actual maintenance costs are generally low. This makes them gain wider acceptance to a large number of people using it.