Principles and features of Karman vortex flow meters
Various types of flow meters and flow sensors are available. This section summarizes the principles and features of Karman vortex flow meters.
Classified as a vortex flow meter, this device utilises a law that was theoretically proven by Theodore von Karman in 1912. When there is a column-shaped obstruction (vortex shedder) in flowing fluid, it will generate alternating vortices downstream. The flow velocity of the fluid and the vortex generation frequency are proportional to each other. Therefore, detecting the number or pulse of vortices makes it possible to measure flow. The main method of detection involves sensing the vortex vibration with a piezo element. However, a more robust method utilises ultrasonic waves to detect the vortex vibration.
PROS | ・No mechanical moving parts. ・Can detect liquids, gases, and vapors. ・Because there are no electrodes, it has specifications that offer excellent chemical resistance. ・Has large range ability and good accuracy. |
---|---|
CONS | ・Because it restricts the flow path, pressure loss will occur. ・Scale deposits and liquids that include solids become the cause of "clogging". ・Not suited for high-viscosity fluids. ・Sensitive to pipe vibrations. ・A section of straight pipe is required. |
CHAPTER 2
FLOW METER TYPES & PRINCIPLES
CHAPTER 2
FLOW METER TYPES & PRINCIPLES