Flow Measurement

What is a vortex flow meter and how is it constructed

What is a vortex flowmeter

A vortex flow meter can be used to measure the flow of gas and liquids, the flow measurement is done by using vortexes. This meter is used to measure the flow of liquid in a pipeline. In this meter, an obstruction or a barrier is used so the barrier will be placed perpendicular to the fluid flow in a pipeline. So when the flow comes in contact with the barrier vibrations will be created. The vibrating frequency of the vortexes is used to measure the flow rate. While the fluid flows through an obstruction the vortices are shed periodically and the shedding frequency is proportional to the average flow velocity.

How vortex flow meters are constructed and how does it work

The vortex flow meters are usually constructed by using stainless steel and Hastelloy. The flow meter consists of a bluff body, a vortex sensor, and an electronic transmitter. The bluff body that is used as obstruction can be in different shapes like it could be rectangular, square, etc. The width of the bluff body must be in the range that it can cover the pipe diameter. The pressure oscillation around the bluff body is detected by using piezoelectric or capacitive type sensors.

The working of the vortex meter is based on the bluff body or obstruction and this obstruction is placed perpendicular to the fluid flow. So when the fluid flows through the pipeline it would be in contact with the bluff body and at the time of the contact the flow will continue around the object but when the fluid is in contact with the obstruction, vortex swirls are created on both sides of the object. Vortices are formed alternately from one side to another and because of this pressure fluctuations are created and these are sensed by the sensor. Thus the flow rate is calculated by measuring the vortices.

How to install a vortex flowmeter

Mostly the vortex flow meters are installed in a straight line, this meter can be installed horizontally or vertically. The vortex meters must be kept flooded. While installing the vortex meter the bores of the meter, gaskets, and the adjacent piping should be carefully aligned. The piping on both sides of the meter must be supported so that the vibrations can be removed. The vortex meter must be placed in the part of the pipeline that has a good flow rate and the flow must be free from distortions or swirls.

What are the advantages of vortex flowmeter

  • It can be used to measure chemicals
  • Better response speed
  • There is no moving part
  • Its measurement  won’t be affected by the density, temperature, pressure, and viscosity
  • It can be used to measure the flow of gas steam and liquids
  • Accuracy and repeatability
  • Low maintenance cost
  • Good flow range
  • Installation cost is less

What are the disadvantages of vortex flowmeter

  • Highly-priced
  • Inline mounting is needed
  • Pressure loss is high
  • It cannot be used to measure for pulsating flow because of the pressure pulsation the measuring won’t be accurate
  • It can only be used to measure clean fluids
  • It must be installed in straight pipe runs
  • It can only be used for unidirectional measurement

What are the applications of vortex flowmeter

  • Steam measurement
  • It can be used for general water metering
  • Chemical industries
  • It is used for the transformation of the natural gas metering
  • It can be used in many process control applications
  • Pressurized gases

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