Flowmeter types and applications Posted by : admin / Posted on : Aug 30， 2019

Classified by flowmeter structure
  1. Impulse flowmeter: The flowmeter weighing impulse flowmeter that measures the flow using the impulse theorem is used to measure the flow rate of granular solid medium, and is also used to measure the flow rate of mud, crystalline liquid and abrasive. Flow measurement ranges from a few kilograms per hour to nearly 10,000 tons. The typical instrument is a horizontal force-separated impulse flowmeter. The measurement principle is that when the measured medium falls freely from a certain height h to a detection plate with a tilt angle, an impulse is generated, and the horizontal force component of the impulse is proportional to the mass flow rate. Measuring this horizontal component can reflect the mass flow. According to the detection method of signal (9), this type of flowmeter is divided into displacement detection type and direct force measurement type.
  2. Electromagnetic flowmeter: The electromagnetic flowmeter is made by applying the electric conductor to generate an induced electromotive force in a magnetic field, and the induced electromotive force is proportional to the flow rate, and is measured by measuring the electromotive force to reflect the principle of the pipeline flow. Its measurement accuracy and sensitivity are high. Industrially used to measure the flow of water, slurry and other media. The maximum diameter can be measured up to 2m, and the pressure loss is extremely small. However, media with low conductivity, such as gas and steam, cannot be used. The electromagnetic flowmeter has a high cost, and the signal is susceptible to external magnetic field interference, which affects the wide application in industrial tube flow measurement. To this end, the product is constantly improving and updating, and it is developing into a computer.
  3. Ultrasonic flowmeter: Ultrasonic flowmeter is designed based on the geometrical principle that the velocity of ultrasonic waves propagating in the flowing medium is equal to the average flow velocity of the measured medium and the velocity of the acoustic wave itself. It is also measured by the flow rate to reflect the flow rate. Although the ultrasonic flowmeter appeared only in the 1970s, it is very popular because it can be made into a non-contact type and can be connected to the ultrasonic water level gauge for opening flow measurement without disturbing or resisting the fluid. There are promising flow meters. Ultrasonic Doppler flowmeters fabricated using the Doppler effect have received widespread attention in recent years and are considered to be ideal gauges for non-contact measurement of two-phase flow.
  4. Fluid oscillating flowmeter: The fluid oscillating flowmeter is designed based on the principle that the fluid will oscillate when flowing under specific flow conditions, and the frequency of the oscillation is proportional to the flow velocity. When the flow cross section is constant, the flow rate is proportional to the flow volume of the pilot volume. Therefore, the flow rate can be measured by measuring the oscillation frequency. This flowmeter was developed and developed in the 1970s. Because it combines the advantages of non-rotating components and pulsed digital output, it has a promising future. Typical
The products include vortex flowmeters and spiral vortex flowmeters.
  5. Mass flow meter: Since the volume of the fluid is affected by parameters such as temperature and pressure, it is necessary to give the parameters of the medium when the flow rate is expressed by the volume flow. In the case of changing media parameters, it is often difficult to achieve this requirement, resulting in distortion of the meter display value. Therefore, mass flow meters have been widely used and valued. Mass flow meters are available in both direct and indirect versions. Direct mass flow meters are measured using principles directly related to mass flow. Currently used mass flow meters such as calorimetric, angular momentum, vibratory gyro, Magnus effect and Coriolis force. The indirect mass flow meter is obtained by directly multiplying the density meter by the volumetric flow rate to obtain the mass flow rate. In modern industrial production, the operating parameters such as temperature and pressure of the flowing working fluid are continuously improved. In the case of high temperature and high pressure, due to the material and structure, the application of the direct mass flowmeter is difficult, and the indirect quality is encountered. Flowmeters are often not suitable for practical applications because they are limited by the range of humidity and pressure. Therefore, a temperature-pressure-compensated mass flowmeter is widely used in industrial production. It can be regarded as an indirect mass flow meter. Instead of using a density meter, it uses the relationship between temperature, pressure and density. It uses a temperature and pressure signal to calculate the density signal by function, and multiplies it by the volume flow. Mass Flow. At present, temperature and pressure-compensated mass flowmeters have been put into practical use. However, when the measured medium parameters vary widely or rapidly, it will be difficult or impossible to correctly compensate, so further study the mass flow rate applicable in actual production. Meters and densitometers are still a topic.
  In addition to the flowmeters of the above-mentioned common structural principles, there are many flowmeters of various structures, such as various helium flowmeters and trough flowmeters suitable for open channel flow measurement; and plug-in flowmeters suitable for large-caliber flow measurement; A laminar flowmeter for measuring laminar flow; a related flowmeter suitable for two-phase flow measurement; and a laser method, a nuclear magnetic resonance flowmeter, a plurality of tracer methods, a dilution flow measurement, and the like. With the development of technology and practical application needs, the new flowmeter will continue to emerge more types of flowmeters.
turbine flowmeter