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Industry Information
Future development of flow meters
2012-1-30 10:32:57

Flow is an important parameter in the modern industrial measurement process. Humans have a long history of measuring fluids.


From the ancient Romans measuring the water flow of residents, the ancient Egyptians measuring the water flow of the river to the modern people's measurement of various industrial process flows, they have fully systemed human infinite wisdom.


In the 20th century, with the application of energy measurement, environmental protection, transportation and other applications to the demand for flow measurement, the flowmeter developed rapidly. Especially the rapid development of microelectronic technology is the manufacturing technology of flow meters

Providing a variety of new components further promotes the development of flowmeters from mechanical to intelligent and modular. The development and application of new technologies, new devices, new materials, new processes and new software make the measurement of flow meters accurate

The degree is getting higher and higher, and the measurement range of the flow is getting wider and wider.


At the same time, the requirements of flowmeters for measuring media are decreasing, the scope of application is becoming wider and wider, and the degree of intelligence and reliability have been greatly improved. Jiangsu Jinhu Dongxiang Instrument Co., Ltd. uses high-tech non-standard development instruments

High-tech enterprises of instrumentation have adopted microelectronic computing technology in large quantities.


Flowmeter classification and principle: There are many ways to classify the flowmeter. For example, it can be classified according to the measurement principle, or it can be classified according to the instrument function and structure type. This article explains the principles and characteristics of various flowmeters one by one.

Distribution of domestic flow meter market: In recent years, starting from the needs of China's industrial development, the use of domestic flow meters has grown rapidly with the development of the economy and industrial applications. The 2003 and 2005 statistics provided by industry associations

According to the analysis of statistical data, the market demand for various flowmeters has increased greatly in 2003 and 2005. Among them, differential pressure transmitters are the largest, followed by float flowmeters.


In recent years, the overall annual growth rate of flow meters has been more than 15%.


Development trend of flow meters: With the development of modern industry, it is necessary to gradually improve its performance, and technological progress has also made it possible to improve the flow meter. The development of flow meters will improve the reliability of flow meters and improve

The adaptability of flowmeters to media and the environment has developed. At the same time, with the application of new signal processing technology and new signal transmission technology, the flowmeter will develop in a highly intelligent direction.


Differential pressure flowmeter


Differential pressure flowmeter is a meter that calculates the flow based on the pressure difference generated by the flow detection element installed in the pipeline, the known fluid conditions, and the geometry of the detection element and the pipeline. The differential pressure flowmeter consists of a detection element (primary device) and

Composed of pressure difference conversion and flow display instrument (secondary device).


The advantages of the differential pressure flowmeter are: solid mechanism, stable and reliable performance, long service life; a wide range of applications, so far no other type of flowmeter can be compared with it; detection parts, transmitters, display instruments are different from plant

⎝⎛星力捕鱼⎞⎠ generation, easy scale generation.


The disadvantages of the differential pressure flowmeter are: the measurement accuracy is generally low; the range is narrow; the site installation conditions are high.


Differential flowmeter is the most widely used type of flowmeter, and its usage ranks first among various flow meters. In recent years, due to the advent of various new flowmeters, the percentage of its use has gradually decreased, but it is still the heaviest

A type of flowmeter required. Its use in various industrial sectors accounts for about 1 / 4-1 / 3 of the total use of the flow meter.


Float meter


Float flowmeter, also called rotor flowmeter, is a type of variable area flowmeter. In a vertical cone tube that is enlarged from bottom to top, the weight of the float with a circular cross section is borne by the liquid power, so that the float can

Freely rise or fall within the cone. Especially in small and micro flow, it plays a pivotal role.


The advantages of the float flowmeter are: the glass cone tube float flowmeter has a simple structure and is easy to use;


The disadvantages of the float flow meter are: low pressure resistance, fragile glass tube, etc.


Float flowmeter is suitable for small diameter and low flow velocity fluid measurement.

3. Positive Displacement Flowmeter


Positive displacement flowmeter is also called fixed displacement flowmeter with high measurement accuracy. It uses mechanical measuring elements to continuously divide the fluid connection into known volume parts, and repeatedly fills and discharges the volume parts according to the measurement chamber.

Divide the number of times to measure the total volume of fluid.
Volumetric flowmeters can be divided into elliptical gear flowmeters, scraper flowmeters, double-rotor flowmeters, rotary piston flowmeters, reciprocating piston flowmeters, original flowmeters, liquid-sealed drum-type flowmeters, and wet-type flowmeters according to their measuring elements. Gas volume

Take into account the membrane gas meter.


The advantages of volumetric flowmeters are: high measurement accuracy; installation pipeline conditions have no effect on measurement accuracy; can be used for measurement of high viscosity liquids; wide range; direct-reading meters can directly obtain the cumulative total without external energy

Clear and easy to operate.


Disadvantages of positive displacement flowmeters are: complex structure and large volume; the type, diameter, and working condition of the medium being tested are limited; they are not suitable for high and low temperature situations; most instruments are only suitable for clean single-phase fluids;

Noisy.


Differential pressure flowmeter


是根据安装于管道中流量检测件产生的压差、已知的流体条件和检测件与管道的几何尺寸来计算流量的仪表。 Differential pressure flowmeter is a meter that calculates the flow based on the pressure difference generated by the flow detection element installed in the pipeline, the known fluid conditions, and the geometry of the detection element and the pipeline. Differential pressure flowmeter consists of detection parts (primary device)

And pressure difference conversion, flow display instrument (secondary device).


The advantages of the differential pressure flowmeter are: solid mechanism, stable and reliable performance, long service life; a wide range of applications, so far no other type of flowmeter can be compared with it; detection parts, transmitters, display instruments are different from plant

⎝⎛星力捕鱼⎞⎠ generation, easy scale generation.


The disadvantages of the differential pressure flowmeter are: the measurement accuracy is generally low; the range is narrow; the site installation conditions are high.


Differential flowmeter is the most widely used type of flowmeter, and its usage ranks first among various flow meters. In recent years, due to the advent of various new flowmeters, the percentage of its use has gradually decreased, but it is still the heaviest

A type of flowmeter required. Its use in various industrial sectors accounts for about 1 / 4-1 / 3 of the total use of the flow meter.


Float meter


Float flowmeter, also called rotor flowmeter, is a type of variable area flowmeter. In a vertical cone tube that is enlarged from bottom to top, the weight of the float with a circular cross section is borne by the liquid power, so that the float can

Freely rise or fall within the cone. Especially in small and micro flow, it plays a pivotal role.


The advantages of the float flowmeter are: the glass cone tube float flowmeter has a simple structure and is easy to use;


The disadvantages of the float flow meter are: low pressure resistance, fragile glass tube, etc.


Float flowmeter is suitable for small diameter and low flow velocity fluid measurement.


3. Positive Displacement Flowmeter


Positive displacement flowmeter is also called fixed displacement flowmeter with high measurement accuracy. It uses mechanical measuring elements to continuously divide the fluid connection into known volume parts, and repeatedly fills and discharges the volume parts according to the measurement chamber.

Divide the number of times to measure the total volume of fluid.


Volumetric flowmeters can be divided into elliptical gear flowmeters, scraper flowmeters, double-rotor flowmeters, rotary piston flowmeters, reciprocating piston flowmeters, original flowmeters, liquid-sealed drum-type flowmeters, and wet-type flowmeters according to their measuring elements. Gas volume

Take into account the membrane gas meter.


The advantages of volumetric flowmeters are: high measurement accuracy; installation pipeline conditions have no effect on measurement accuracy; can be used for measurement of high-viscosity liquids; wide range; direct-reading meters can directly obtain the cumulative total without external energy

The amount is clear and easy to operate.


Disadvantages of positive displacement flowmeters are: complex structure and large volume; the type, diameter, and working condition of the medium to be measured are limited; they are not suitable for high and low temperature situations; most instruments are only suitable for clean single-phase fluids;

Vibration and noise are large.


4.Turbine flowmeter


The turbine flow meter uses a multi-blade turbine rotor to sense the average speed of the fluid, and derives the flow or total meter; it consists of two parts: a sensor and a display.


The advantages of turbine flowmeters are: accurate flow measurement, good renaturation, zero drift, strong interference ability, wide range and compact structure.


的缺点有:不能长期保持校准特性、体物性对流量特性有较大影响。 The disadvantages of the turbine flowmeter are that it cannot maintain calibration characteristics for a long time, and physical properties have a large impact on flow characteristics.


Turbine flowmeters are widely used in the measurement of organic liquids, petroleum, inorganic liquids, natural gasification gas, and low-temperature circulation.

5. Electromagnetic flowmeter


The electromagnetic flowmeter uses Faraday's law of electromagnetic induction to measure the flow velocity, and then uses some method to measure the liquid level of the cross section of the flow to obtain the flow area. Multiply the two to obtain the flow.


The electromagnetic flowmeter has a series of excellent characteristics, which can solve the problems that other flowmeters cannot easily solve, such as the measurement of dirty and corrosive flows.

The advantages of the electromagnetic flowmeter are: the measurement channel is a smooth straight tube and it will not be blocked. It is suitable for measuring liquid-solid two-phase fluids containing solid particles, such as pulp, mud, sewage, etc .; no pressure loss caused by flow detection,

The energy saving effect is good; the measured volume flow is actually not significantly affected by changes in fluid density, viscosity, temperature, pressure, and conductivity; the flow range is wide and the caliber range is wide; it can be applied to corrosive fluids.



的缺点:不能测量电导率很低的液体,如石油制品。 Disadvantages of electromagnetic flowmeters : cannot measure liquids with very low conductivity, such as petroleum products. Capable of measuring gases, vapors, and liquids with large bubbles; cannot be used at higher temperatures. The electromagnetic flowmeter has a wide range of applications, large mouth

Diameter instruments are mostly used in water supply and drainage projects; small and medium-caliber instruments are often used in high-demand or difficult-to-measure applications, such as cooling water control in the blast furnace tuyere of the iron and steel industry, pulp and black liquor in the paper industry, strong corrosive fluids in the chemical industry, non-ferrous

Metallurgical industry's pulp; small-caliber and micro-caliber instruments are often used in places with hygienic requirements such as the pharmaceutical industry, food industry, and biochemistry.


In the 1970s and 1980s, electromagnetic flowmeters made major breakthroughs in technology, making it a widely used type of flowmeter, and the usage rate has continued to rise.

6. Vortex flowmeter


A vortex flowmeter is a meter in which a non-streamline vortex generator is placed in a fluid, and the fluid alternately separates on both sides of the generator to release two series of regularly staggered vortex generators.


According to the frequency detection method, it can be divided into stress type, strain type, capacitive type, thermal type, vibrating body type, photoelectric type, and ultrasonic type. They are the youngest type of flowmeters, but they have developed rapidly and have become universal. A type of flow meter.


的缺点:不适用于低雷诺数测量、较长直管段、表系数较低(与涡轮流量计相比)、表在脉动流、多相流中尚缺乏应用经验 Disadvantages of vortex flowmeters : Not suitable for low Reynolds number measurement, long straight pipe sections, low table coefficient (compared to turbine flowmeters), and lack of application experience in pulsating flow and multiphase flow


The vortex flowmeter has the advantages of simple and firm structure, many types of fluids, high degree, wide range, and small loss.


7. Ultrasonic flowmeter


An ultrasonic flowmeter suitable for natural gas storage transfer measurement; low transmission efficiency of ultrasonic waves on the solid-gas interface; it is difficult to mount an ultrasonic transducer (probe) outside the channel to transmit sufficient sound energy from the pipe wall; this has not yet

There are externally clamped gas ultrasonic flowmeters.

Gas ultrasonic flowmeters began in the early 1980s. Most of them consisted of a measuring tube and a transducer inserted into the tube wall. Due to the low measurement accuracy, in the past, it was not possible to measure in the expensive natural gas trade settlement.

It has a place in the field, and in recent years, a variety of high-precision gas ultrasonic flowmeters have appeared.


The ultrasonic flowmeter uses the physical properties of ultrasonic waves with different propagation speed in different liquids to identify the type of liquid in the pipeline while measuring the flow rate.

For example, in Europe, an ultrasonic flowmeter is often used to measure the flow rate when the ship is unloaded into the warehouse, and at the same time, it is judged whether the liquid being transported is oil or the bottom water of the tanker.


An ultrasonic flow meter is a meter that measures the flow by detecting the effect of fluid flow on an ultrasonic beam (or ultrasonic pulse).


According to the principle of signal detection, ultrasonic flowmeters can be divided into the propagation velocity difference method (direct time difference method, time difference method, phase difference method, and frequency difference method); beam shift method; Pooler method; indirect filtering method and noise method, etc. .


Ultrasonic flowmeters are the same as electromagnetic flowmeters. Because the flow channel of the instrument is not provided with any obstructions, they are all unobstructed flowmeters. They are a type of flowmeter that is suitable for solving the difficult problem of flow measurement, especially for large-caliber flow measurement.

The more prominent advantage is one of a class of flowmeters that has developed rapidly in recent years.


的优点有:可做非接触式测量;无流动阻挠测量,无压力损失;可测量非导电性液体,对无阻挠测量的电磁流量计是一种补充。 The advantages of ultrasonic flowmeters are: non-contact measurement; no flow obstruction measurement and no pressure loss; non-conductive liquids can be measured, which is a complement to the electromagnetic flowmeter without obstruction measurement.


Disadvantages of ultrasonic flowmeters are: the time-of-flight ultrasonic flowmeter can only be used to clean liquids and gases; the Doppler ultrasonic flowmeter can only be used to measure liquids containing a certain amount of suspended particles and bubbles; the Doppler ultrasonography

The measurement accuracy of the acoustic flowmeter is not high.


8. Coriolis flowmeter


The Coriolis flowmeter uses the phase difference of the vibration frequency of the measuring tube to be proportional to the mass flow rate to measure the flow rate, and uses the function relationship between the resonance frequency of the measuring tube and the density of the medium in the tube to determine the density.


Coriolis flowmeter also derives volume flow rate qv from two basic parameters, mass flow rate qm and density ρ; if the measured liquid is two mixed liquids with a certain density difference, a liquid can also be obtained through density calculation Concentration in the mixture.


Due to the different measuring principles of different flowmeters, the uses of flowmeters are not the same, so far no one flowmeter is universal.


Each type of flowmeter is always limited in use due to the limitations of its measuring principle, its ability to adapt to the type of measurement medium, the characteristics of the measurement medium and the characteristics of flow changes, and the ability to adapt to environmental conditions.


Because of this, while new flowmeters continue to appear, some traditional flowmeters with a long application history are still widely used.