Instrument Mesurement Knowledge

Four Different Types of Water Flow Meter

Views: 16     Author: Site Editor     Publish Time: 2021-10-29      Origin: Site

          In the market, there are four main types of water flow meters: mechanical water flow meters, ultrasonic flow meters, vortex street volume flow meters or magnetic flow meters. Today, we will introduce the four flowmeters from the aspects of working principle, advantages and disadvantages, etc.


Mechanical water flowmeter



  • Working principle


          This type of water flowmeter uses splitter, propeller or paddle wheel technology to measure water flow through the rotation of turbine. When water flows through the pipeline, the turbine of the mechanical water flowmeter will rotate. The volume flow of water is proportional to the rotating speed of the blade.


  • Advantages of mechanical water flowmeter

      The most economical type


  • Disadvantages of mechanical water flowmeter

           If there are large particles in the measured water, it is easy to block the mechanical water flowmeter. This will increase the maintenance cost. In addition, the mechanical water flowmeter has poor performance at low flow rate.


Vortex flow meter 



  • Working principle


      Vortex flowmeter uses the principle of fluid oscillation to measure flow. When the fluid passes through the eddy current transmitter in the pipeline, two rows of eddy currents proportional to the flow rate are alternately generated up and down after the triangular cylinder eddy current generator. The release frequency of eddy current is proportional to the flow rate.


  • Advantages of vortex flow meter

       Its characteristics are small pressure loss, large measuring range and high precision. When measuring the volume flow under working condition, it is hardly affected by the parameters such as fluid density, pressure, temperature and viscosity. No movable mechanical parts, high reliability and little maintenance. The instrument parameters can be stable for a long time.


  • Disadvantages of vortex flow meter

       This kind of flowmeter is relatively expensive, and is mainly used for measuring gas and steam media.


Ultrasonic flowmeter


  • Working principle

     Ultrasonic open channel flowmeter is a non-contact instrument, which uses the principle of acoustic reflection to detect the liquid level in the weir groove, and obtains the water flow through the weir groove through conversion.


  • Advantages of ultrasonic flow meter

      The application range of liquid ultrasonic flowmeter is very wide (the pipe diameter is from 12mm to 5m or even larger), and the pipe diameter is from DN80 to DN1000. The selected instrument adopts acoustic waveguide technology and can withstand various extreme process conditions (temperature range:-200 ~ 600℃; Pressure range: it can be at the same level as the process flange).


  • Disadvantages of vortex flow meter

      Due to the inherent weaknesses of ultrasonic and electronic measuring instruments, such as being susceptible to temperature and radiation, improper installation and use will seriously affect their measuring accuracy and service life.


       Electromagnetic flowmeter

  •  Working principle

      Electromagnetic flowmeter is a flowmeter that measures the flow according to Faraday's electromagnetic induction law. When the conductive fluid flows through the magnetic field perpendicular to the flow direction, the conductive fluid induces an induced voltage E proportional to the average flow rate. The induced voltage is detected by two electrodes in direct contact with the fluid, and then amplified, filtered and shaped by the converter. Send it to the transmitter to complete the display and output control of instantaneous flow and cumulative flow.


  • Advantages of electromagnetic flow meter

      Compared with other flowmeters, the electromagnetic flowmeter has no choke parts in the measuring tube, which is not easy to block and has low maintenance cost. The requirements for straight pipe sections at the front end are relatively low.

      The sensor of electromagnetic flowmeter is simple in structure, and there is no or no throttling component that hinders the flow of fluid in the measuring pipe. Therefore, when the fluid passes through the flowmeter, it will not cause any extra pressure loss. It is one of the flowmeters with low energy consumption.

      Electromagnetic flowmeter has no mechanical inertia, and its response is more sensitive. It can measure the instantaneous flow, and it can also measure the flow in both positive and negative directions.

     Widely used, choose different electrodes and linings to measure dirty and corrosive medium.

     Electromagnetic flowmeter is a kind of volume flow measuring instrument. In the process of measurement, it is not affected by the temperature, viscosity and density of the measured medium, and the measurement accuracy is high.


  • Disadvantages of electromagnetic flow meter

      Magnetic flow meter cannot measure medium with low conductivity, such as pure water


      Above on,electromagnetic flow meter is the most appropriate type flow meter for water fluid measurement.