Flow measurement is one of the four important process parameters (the others being temperature, pressure, and level).

Differential pressure flow meter （DP） This is the most common flow technology, including orifice plates, Venturi tubes, and sonic nozzles.DPFlow meters can be used to measure the flow rate of most liquids, gases, and vapors.DPThe flowmeter has no moving parts, is widely used, and easy to use. But after blockage, it will cause pressure loss, affecting accuracy. The accuracy of flow measurement depends on the precision of the pressure gauge.

Volumetric flowmeter（PD）PDFlow meters are used to measure the volumetric flow rate of liquids or gases, introducing the fluid into the measuring space and calculating the number of rotations. Impellers, gears, pistons, or orifice plates are used to divert fluid.PDFlow meters have high accuracy and are one of several methods for measuring viscous liquids. But it can also generate irreparable pressure errors and require the installation of moving parts.

turbine flow meter When the fluid flows through the turbine flowmeter, the fluid causes the rotor to rotate. The rotational speed of the rotor is related to the velocity of the fluid. Average fluid velocity perceived through the rotor,Derive traffic or total amount. Turbine flow meters can accurately measure clean liquids and gases. likePDFlow meters and turbine flow meters can also generate irreparable pressure errors and require moving parts.

Electromagnetic Flowmeter When a fluid with conductivity flows through an electromagnetic field, the velocity of the fluid can be obtained by measuring the voltage. Electromagnetic flow meters have no moving parts and are not affected by fluids. The accuracy of measuring conductive liquids is very high when the tube is full. Electromagnetic flow meters can be used to measure the flow velocity of slurry fluids.

ultrasonic flow meter The propagation time method and Doppler effect method are commonly used in ultrasonic flow meters to measure the average velocity of fluids. Like other speedometers, it is an instrument for measuring volumetric flow rate. It is a flow meter, and if the ultrasonic transmitter is installed outside the pipeline for measurement, it does not need to be inserted. It is suitable for almost all liquids, including slurries, with high precision. But the contamination of pipelines can affect accuracy.

vortex flow meter It is to place a non streamlined vortex generator in the fluid,The velocity of the vortex is proportional to the velocity of the fluid, thus calculating the volumetric flow rate. Vortex flowmeter is suitable for measuring liquids, gases, or vapors. It has no moving parts and no dirt issues. Vortex flow meters generate noise and require high fluid velocity to generate vortices.

Thermal mass flowmeter Measure fluid velocity by measuring the increase in fluid temperature or the decrease in thermal sensor. Thermal mass flow meters have no moving parts or holes and can accurately measure the flow rate of gases. Thermal mass flowmeter is one of the few technologies that can measure mass flow rate and is also one of the few technologies used to measure large-diameter gas flow rate.

Coriolis flowmeter This flowmeter uses a vibrating fluid tube to produce a deflection corresponding to the mass flow rate for measurement. Coriolis flowmeter can be used for measuring the mass flow rate of liquids, slurries, gases, or vapors. High precision. But regular maintenance should be carried out on the pipeline wall to prevent corrosion.

Principles for selecting flow meters

In summary A flowmeter is a type of measuring product that conforms to the general law of value. The higher the accuracy, the higher the price, the heavier the weight, the higher the price, and the more functions there are, the higher the price. Imported products are more expensive than domestically produced ones.
Since we are talking about selection principles, we must consider factors such as functionality and price. For example, if a user only needs to measure the instantaneous flow rate of water in a four inch pipeline, most flow meters can meet the measurement requirements, which is relatively lowThe price of a grid may be several hundred yuan, while the price of a grid may be several hundred thousand yuan. It all depends on how the user chooses.

Measuring liquids measure gas There are different flow meters available.
Can you briefly explain the applicable situations Arrange according to the same caliber price from low to high
Measuring liquids Glass rotor flowmeter orifice plate Elliptical gear flowmeter turbine flow meter Metal rotor flowmeter Electromagnetic Flowmeter vortex flow meter ultrasonic flowmeter mass flow meter
measure gas Glass rotor flowmeter orifice plate Metal rotor flowmeter turbine flow meter vortex flow meter

Principles and selection methods of various flow meters

Analysis of Turbine Flow Meter
1 The working principle of a turbine transmitter is that a turbine flowmeter consists of a turbine, bearings, a preamplifier, and a display instrument.
The tested fluid impacts the turbine blades, causing the turbine to rotate. The rotational speed of the turbine changes with the flow rate, that is, as the flow rate increases, the rotational speed of the turbine also increases. The rotational speed of the turbine is then converted into electrical pulses of the corresponding frequency by a magneto electric conversion device, amplified by a preamplifier, and sent to a display instrument for counting and display. The instantaneous and cumulative flow rates can be calculated based on the number of pulses per unit time and the cumulative number of pulses.
The working principle of a turbine transmitter is that when the fluid flows along the axis of the pipeline and impacts the turbine blades, there is an increase in flow rateqvFlow rateVAnd fluid densityρA force proportional to the product acts on the blades, driving the turbine to rotate. While the turbine rotates, the blades periodically cut the magnetic field lines generated by the electromagnet, changing the magnetic flux of the coil. According to the principle of electromagnetic induction, a pulsating electric potential signal will be induced in the coil, and the frequency of this pulsating signal is proportional to the flow rate of the measured fluid.
The pulse signal output by the turbine transmitter can be amplified by an amplifier before being sent to the display instrument for flow measurement.
2 Selection of Turbine Flow Meter
（1）The flowmeter body is best selected for use316Stainless steel material is used for corrosion prevention, and in explosion-proof areas, it must also have explosion-proof results.
（2）Bearings generally come in three specifications: tungsten carbide, polytetrafluoroethylene, and carbon graphite. Tungsten carbide has the highest precision and is used as a standard component for industrial control; Polytetrafluoroethylene and carbon graphite have anti-corrosion properties and are generally preferred in chemical facilities. The lifespan of a bearing is inversely proportional to the square of the flow rate, so the flow rate is goodAt the maximum flow rate1/3The speed is relatively good.
（3）Induction probe detects the motion of a rotating body and converts it into a pulse digital electrical signal. Its electromagnetic coil voltage output value is close to a sine curve, and the frequency range of the pulse signal varies linearly with the measured flow rate. The typical range is10:1，25:1and100:1Three specifications. The resistance of an electromagnetic coil is generally less than2000ΩExceeding this value may result in damage.
3Installation of turbine flowmeter
（1）The power cord of the transmitter adopts metal shielded wire, and the grounding should be good and reliable. The power supply is DC24V，650ΩImpedance.
（2）The transmitter should be installed horizontally, avoiding vertical installation, and ensuring that there are suitable straight pipe sections before and after it. Generally, the front10D, behind5D.
（3）Ensure that the flow direction of the fluid is consistent with the arrow direction on the instrument casing, and do not install it in reverse.
（4）The tested medium should not corrode the turbine, especially at the bearings, otherwise measures should be taken.
（5）Be careful not to collide with the magnetic induction part.
4Configuration and calibration of turbine flowmeter
The standard calibration method is the ten point water calibration method, but the calibration values vary depending on the viscosity, so a viscosity calibration curve is usually required.
5Display instrument for turbine flowmeter
The task of the display instrument is to convert the number of output pulses per unit time and the total number of output pulses into instantaneous flow rate and total flow rate, and display them.
The pulse signal output by the preamplifier has irregular amplitude and waveform. After entering the display instrument, it needs to be shaped by a shaping circuit into a regular rectangular electrical pulse signal with a certain amplitude, and then passed through a frequency/Current conversion circuit, which converts frequency signals into corresponding current signals（4～20mA）The instantaneous flow rate value can be converted again, and the total amount is obtained by the conversion and integration circuit. Some display instruments display on site, while others sendDCSDisplay.
6Precautions
（1）Before installing the turbine flowmeter, the pipeline should be cleaned. When the tested medium is unclean, a filter should be added. Otherwise, the turbine and bearings are prone to getting stuck and the flow rate cannot be measured.
（2）Disassemble the flowmeter without colliding with the magnetic induction part.
（3）Set the instrument coefficient before putting it into operation. Carefully check and ensure that the instrument wiring is correct and well grounded before power can be transmitted.
（4）When installing a turbine flowmeter, the flanges of the front and rear pipelines should be level, otherwise the pipeline stress will have a significant impact on the flowmeter.
7development prospects
With the continuous development of science, today's turbine transmitters have evolved into miniaturized and highly integrated modules, designed with powerful functional software and equipped withRS232The standard computer communication interface provides convenience for maintenance and repair. can be paired withDCSConnect communication,DCSReplaced the display instrument, such asHOFFERFlow meters are more convenient and practical in industrial production processes.
In summary, turbine flowmeter is a type of velocity flow instrument that is widely used in chemical production due to its high measurement accuracy, fast reaction speed, wide measurement range, low cost, and easy installation.

Basic knowledge of several flow meters

Flow measurement is one of the four important process parameters(The others are temperature, pressure, and level)The closed pipeline flow meters are classified according to the technology they use as follows:

1： Differential pressure flowmeter(DP)

This is the most common flow technology, including orifice plates, Venturi tubes, and sonic nozzles. Flow meters can be used to measure the flow rate of most liquids, gases, and vapors.DPThe flowmeter has no moving parts, is widely used, and easy to use. But after blockage, it will cause pressure loss, affecting accuracy. The accuracy of flow measurement depends on the precision of the pressure gauge.

2： Turbine flowmeter

When the fluid flows through the turbine flowmeter, the fluid causes the rotor to rotate. The rotational speed of the rotor is related to the velocity of the fluid. Derive the flow rate or total amount based on the average fluid velocity sensed by the rotor. Turbine flow meters can accurately measure clean liquids and gases. likePDFlow meters and turbine flow meters can also generate irreparable pressure errors and require moving parts.

3： Electromagnetic flowmeter

When a fluid with conductivity flows through an electromagnetic field, the velocity of the fluid can be obtained by measuring the voltage. Electromagnetic flow meters have no moving parts and are not affected by fluids. The accuracy of measuring conductive liquids is very high when the tube is full. Electromagnetic flow meters can be used to measure the flow velocity of slurry fluids.

Measurement principle: Faraday's law of electromagnetic induction proves that a conductor moving in a magnetic field will induce an electric potential. Using the principle of electromagnetic measurement, fluid is a conductor in motion. The induced potential is proportional to the flow rate and is detected by two measuring electrodes. Then, the transmitter amplifies it and calculates the flow rate based on the cross-sectional area of the pipeline.

A constant magnetic field is generated by switching DC currents with alternating polarity.

The measurement system consists of a transmitter and a sensor.

It has two models: integrated type, where the transmitter and sensor form an integrated mechanical unit; Separate type, the transmitter and sensor are installed separately.

Transmitter:Promag50(Operated with buttons, displayed in two lines)Sensor:PromagW(DN25……2000)

Technical Specifications

Measurement variable: flow velocity.

Input variable measurement range: Typicalv=0.1……10m/sOperable flow range with measurement accuracy: exceeding1000：1Input signal status input(Auxiliary input)：U=3…30vDC，Ri=5kΩElectrical isolation. Configurable: Cumulative measurement(S)Reset, suppress measurement values, and reset error messages.

current input(Only whenPromag53): Active/Passive optional, electrical isolation resolution:2μAActive:4...20mA，Ri≤150Ω，Uout=24VDC, anti current short circuit

Passive:0/4...20mA，Ri≤150Ω，Umax=30VDC.

output variable

Output signal current output:active/Passive optional, electrically isolated, time constant optional(0.05...100s), full-scale value optional, temperature coefficient:typical0.005%o.r./℃;resolution:0.5μA

Active:0/4...20mA，RL<700Ω(HART:RL≥250Ω)

Passive:4...20mA，max.30VDC，Ri≤150Ω

pulse/frequency output:Passive, open collector30VDC，250mAElectrical isolation.frequency output:Full range frequency2...1000Hz(fmax=1250Hz)Open it/Closing ratio1:1

pulse width:maximum10s.pulse output:Pulse value and polarity are optional, and the maximum pulse width can be set(0.05...2s)The maximum pulse frequency can be selected from the transmitter housing, which is an integrated housing made of powder coated cast aluminum; Wall mounted casing: cast aluminum sensor casing,DN25...300Powder coated cast aluminum;DN350...2000Specification Description of Coated Steel Model:50W9H-UD0A1AK2C4AW(DN900)，50Wexactly.50Series;9HThe caliber is900mm(DN900)；UIndicating that the substrate material is polyurethane;DRepresenting process connections/The material isPN10DIN250l，ST37-2flange(Applicable toDN200-DN2000)；0Representing electrode materials(All electrodes)for1.4435/316Lstainless steel;AIndicating calibration as0.5%.3Point calibration;1Indicating that certification does not require special certification; the secondAIndicates no riot control requirement;KIndicating shell protection, etcIP68Separate type, wall mounted type;2Indicating that the separation type comes with its own10mCable;

Environmental conditions: ambient temperature-20...+60℃(Sensors, transmitters)Install in a dark place, avoiding direct sunlight, especially in warm climate areas.

Reference conditions for measurement accuracy: Compliant withDIN19200andVDI/VDE264l, medium temperature:+28℃±kEnvironmental temperature:+22℃±kPreheating time:30minute

During installation, it should be noted that accurate measurements can only be obtained when the pipe is full, avoiding the following installation positions: installation at the highest point of the pipe(Easy to accumulate bubbles)Directly installed in front of the open outlet of a downward pipeline.

Be careful not to install a flow pipe on the inlet side of the pump to avoid damage to the flow pipe lining caused by pumping. When using reciprocating, diaphragm or plunger pumps, it is necessary to install a pulse throttle valve.

When the length of the downward pipeline exceeds5mInstall a siphon or a vent valve behind the sensor. To avoid potential damage to the lining of the measuring tube caused by low pressure. Ensure full tube and reduce gas content.

Installation orientation: The most suitable orientation can help avoid gas accumulation and residue accumulation inside the measuring tube.

Vertical installation; This orientation is ideal for self emptying pipeline systems and does not require the use of empty tube detection electrodes.

Horizontal installation: The measuring electrode plane must be horizontal to prevent short-term insulation of the electrode caused by entrained bubbles. Attention: The air traffic control detection function can only work correctly when the measuring device is installed horizontally and the transmitter housing is facing upwards. If the vibration is very severe, the sensor and transmitter should be installed separately.

Base, support: if the nominal diameter isDN≥350Install the transmitter on a base that can withstand sufficient load. Please note that it is not allowed to use the outer frame to support the weight of the sensor. This will cause deformation of the outer frame and damage to the internal excitation coil. If possible, it is best to avoid components such as valves, tees, elbows, etc. when installing sensors.

Ensure the following required inlet and outlet straight pipe sections to ensure measurement accuracy: inlet length>10×DNExport length>5×DNSensors and transmitters with grounding sensors located at the center of the pipeline

Grounding: The sensor and medium must have the same potential to ensure measurement accuracy and avoid electrode corrosion damage. The equipotential is ensured by installing a ground reference electrode inside the sensor. If the medium flows in an unlined and grounded metal tube, it can meet the grounding requirements by connecting to the transmitter housing. For separated grounding, the same applies as above.

Attention: If it is uncertain whether the medium is correctly grounded, a grounding ring should be installed.

Fault diagnosis: If the electromagnetic flowmeter malfunctions after startup or during operation, it is usually diagnosed according to the following checklist to directly find the cause of the problem and corresponding solutions.

Check for no display and no output signal:1Check the power terminals1，2；2Check the fuse.

No display but signal output:1Check if the cable connection of the display module is correctly inserted into the amplification board;2The display module is damaged;3The measuring electrode is damaged.

Display text in foreign language: Turn off the power while holding down+/-Press the key and power on the measuring instrument, and the displayed text will be in English(default)And it is at the maximum display contrast.

The measured value is displayed, but there is no current or pulse output signal: the measuring electrode is damaged.

Display fault: During debugging or measurement, faults will be immediately displayed. The fault information will include some symbols, which have the following meanings:S=Fault informationP=Process malfunction=Fault information!=Warning messageEMPTYPIPE=Fault type, i.e. partially full or empty measuring tube03：00：05=Fault occurrence time, hours/minute/second#401=Fault code current output: minimum current,4-20mA(25mA) →2mAThe output signal corresponds to zero flow; Maximum current,4-20mA(25mA) →25mA.

Note: Defined as“Warning message“System or process failures have no impact on input/output.

4： The propagation time method and Doppler effect method are commonly used in ultrasonic flow meters to measure the average velocity of fluids. Like other speedometers, it is an instrument for measuring volumetric flow rate. It is a flow meter, and if the ultrasonic transmitter is installed outside the pipeline for measurement, it does not need to be inserted. It is suitable for almost all liquids, including slurries, with high precision. But the contamination of pipelines can affect accuracy. Ultrasonic flow meters are becoming increasingly widely used in the industrial sector because they can effectively measure natural gas flow rates. This measurement is non intrusive and will not cause pressure loss. Ultrasonic flow meters require relatively clean fluids.

5： Vortex flowmeter is a device that places a non streamlined vortex generator in a fluid, and the velocity of the vortex is proportional to the velocity of the fluid, in order to calculate the volumetric flow rate. Vortex flowmeter is suitable for measuring liquids, gases, or vapors. It has no moving parts and no dirt issues. Vortex flow meters generate noise and require high fluid velocity to generate vortices.

Vortex flowmeter is mainly used for flow measurement of industrial pipeline medium fluid,Various media such as gases, liquids, vapors, etc. Its characteristic is low pressure loss,Large measuring range,high precision,When measuring the volumetric flow rate under working conditions, it is almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc. There are certain differences between turbine flow meters and electromagnetic flow meters.No movable mechanical parts, therefore high reliability,The maintenance volume is small. The instrument parameters can remain stable for a long time. This instrument adopts piezoelectric stress sensor,high reliability,can be-20℃～+250Working within the temperature range of ℃. There are analog standard signals available,There are also digital pulse signal outputs,Easy to use in conjunction with digital systems such as computers,It is a relatively advanced and ideal flow meter.

The principle is to set up a triangular cylindrical vortex generator in the fluid, which alternately generates regular vortices from both sides of the vortex generator. This type of vortex is called a Karman vortex, as shown in the figure on the right. The vortex columns are asymmetrically arranged downstream of the vortex generator.

　　 Let the frequency of vortex occurrence befThe average flow velocity of the measured medium is, and the width of the upstream face of the vortex generator isdThe diameter of the body isD, the following relationship can be obtained:f=SrU1/d=SrU/md　　　　　　　　　　　　　　　　　　　　(1)

In the formulaU1--The average flow velocity on both sides of the vortex generator,m/s；

　　　　Sr--Strouhal number;

　　　　m--The ratio of the bow shaped area on both sides of the vortex generator to the cross-sectional area of the pipeline

　　　　　　　　 Volume flow rate inside the pipelineqvfor

　　　　　　　　　　　　qv=πD2U/4=πD2mdf/4Sr　　　　　　　　　　　　　　　　(2)

　　　　　　　　　　　　K=f/qv=[πD2md/4Sr]-1　　　　　　　　　　　　　　　　(3)in the formulaK--Instrument coefficient and pulse count of flowmeter/m3(P/m3).

　　KIn addition to the geometric dimensions of the vortex generator and pipeline, it is also related to the Strouhal number. The Strouhal number is a dimensionless parameter that is related to the shape of the vortex generator and the Reynolds number2The diagram shows the relationship between the Strouhal number of a cylindrical vortex generator and the Reynolds number of a pipeline. As can be seen from the figure, inReD=2×104～7×106Within the scope,SrRegarded as a constant, this is the normal operating range of the instrument. When measuring gas flow rate,VSFThe flow calculation formula is

In the relationship curve between Strouhal number and Reynolds numberqVn，qV--Under standard conditions(0oCor20oC，101.325kPa)And the volumetric flow rate under operating conditions,m3/h；

　　Pn，P--The absolute pressure under standard conditions and operating conditions, respectively,Pa；

　　Tn，T--The thermodynamic temperatures under standard conditions and operating conditions, respectively,K；

　　Zn，Z--They are the gas compression coefficients under standard conditions and operating conditions, respectively.

　　 As can be seen from the above equation,VSFThe output pulse frequency signal is not affected by fluid properties and composition changes, that is, the instrument coefficient is only related to the shape and size of the vortex generator and pipeline within a certain Reynolds number range. However, as a flowmeter in material balance and energy measurement, it is necessary to detect mass flow rate. At this time, the output signal of the flowmeter should simultaneously monitor volume flow rate and fluid density. Fluid properties and components still have a direct impact on flow measurement. The vortex flowmeter is a new type of flowmeter that measures fluid flow in closed pipelines based on the Karman vortex principle. Due to its excellent medium adaptability, it can directly measure the volumetric flow rate of steam, air, gas, water, and liquid without temperature and pressure compensation. Equipped with temperature and pressure sensors, it can measure standard volumetric flow rate and mass flow rate, making it an ideal alternative to throttling flow meters.

　　 To improve the high temperature resistance and vibration resistance of vortex flowmeters, our company has recently developedHLUGImproved vortex flow sensor, due to its * structure and material selection, can withstand high temperatures(350℃)Strong vibration(≤1g)Used under harsh working conditions.

　　 In practical applications, the maximum flow rate is often much lower than the upper limit value of the instrument, and with changes in load, the minimum flow rate is often lower than the lower limit value of the instrument. The instrument is not working in its optimal working range. To solve this problem, it is usually necessary to reduce the diameter at the measuring point to increase the flow velocity at the measuring point, and select a smaller diameter instrument to facilitate the measurement of the instrument. However, this variable diameter method must have a length of between the variable diameter pipe and the instrument15DThe above straight pipe sections are rectified, making processing and installation inconvenient. The longitudinal section shape developed by our company is a circular arcLGZVariable diameter rectifier has multiple functions of rectification, increasing flow velocity, and changing flow velocity distribution. Its structural size is small, only about the inner diameter of the process tube1/3Integrated with the vortex flowmeter, it not only eliminates the need for an additional straight pipe section, but also reduces the requirements for the straight pipe section of the process pipe, making installation very convenient. For the convenience of use, the battery powered local display vortex flowmeter adopts low-power high-tech. It can operate continuously for more than a year with lithium battery power supply, saving the procurement and installation costs of cables and display instruments. It can display instantaneous flow, cumulative flow, etc. on site. The temperature compensated integrated vortex flowmeter also comes with a temperature sensor, temperature transmitter, pressure transmitter, and pressure transmitter. It can directly measure the temperature of saturated steam and calculate the pressure, thereby displaying the mass flow rate of saturated steam. The integrated temperature and pressure compensation system is equipped with temperature and pressure sensors, which can directly measure the temperature and pressure of the gas medium for gas flow measurement, thereby displaying the standard volumetric flow rate of the gas.

6： Vortex flowmeter 1: Principle: When the fluid flowing along the axial direction enters the inlet of the flow sensor, the vortex generator forces the fluid to undergo rotational motion, thus generating a vortex flow at the center of the vortex generator. The vortex flow spirals in the Venturi tube and reaches the contraction section, where it suddenly throttles and accelerates. When the vortex enters the diffusion section, it is forced to undergo a second spiral rotation due to the backflow effect. At this point, the rotational frequency of the vortex flow is proportional to the velocity of the medium and is linear. The weak charge signals detected by two piezoelectric sensors are differentially amplified, filtered, and shaped by a preamplifier to become two pulse signals with frequencies proportional to the flow rate. At the same time, the processing circuit compares and distinguishes the phase of the two pulse signals to eliminate interference signals,And count and process normal traffic signals.

2： Purpose: Mainly used to replace differential pressure flow meters. This type of flowmeter can be used to measure the flow rate of clean, low viscosity, medium to high speed fluids. In recent years, new types of measuring instruments suitable for different media and working conditions have emerged one after another, and the intelligent vortex flowmeter is one of them. It is a speed flow instrument developed and put on the market in recent years, which can be used for flow measurement of various media such as oil, steam, natural gas, water, etc., and realizes online automatic compensation of dynamic parameters such as pressure, temperature, and compression coefficient.

　　① In certain specific situations, orifice flow meters can no longer meet the most basic measurement requirements. At the natural gas flow measurement site, there are often some special users, mainly manifested as small instantaneous flow or large flow fluctuation amplitude. If traditional orifice flow meters are still used for flow measurement in this situation, it is likely to violate the relevant technical standards. For example, requirements'The flow rate inside the pipeline should not change over time, or in fact, only have small and slow changes over time'For orifice flow meters that use flange pressure measurement, once these basic usage conditions are exceeded, the measurement accuracy of orifice flow meters cannot be discussed; In addition, in this special situation, the selection of display instruments is also a complicated task. If the matching is not appropriate, it is inevitable that the indication or recorded value will exceed the tolerance.

　　② Strict control of production management costs is an urgent requirement for the survival and development of modern enterprises. Nowadays, various enterprises are undergoing severe market baptism, and production costs are crucial to the survival of enterprises. Therefore, on the premise of meeting the basic requirements of flow meters, the selection of new measuring instruments that can save static investment and reduce dynamic costs has been put on the agenda of relevant decision-makers.

3： Compared with traditional orifice flowmeters, the intelligent vortex flowmeter has the following main characteristics:

　　① Implemented mechatronics integration, eliminating the need for manual monitoring in daily measurement processes;

　　② The installation conditions for the process are not strict, and the straight pipe sections upstream and downstream of the instrument can be greatly shortened compared to orifice flow meters;

　　③ The measurement accuracy of the system can meet the current requirements of trade measurement(≤2%)'>；

　　④ Wide flow measurement range(qmax/qmin=15～20'>)It can effectively work in small flow areas that cannot be reached by orifice flow meters;

　　⑤ Small size, light weight, and convenient offline calibration;

　　⑥ The measurement signal can be displayed locally or transmitted remotely as needed;

　　⑦ There are no movable parts, so there is no mechanical wear of the instrument for general measurements;

　　⑧ Instrument management personnel do not require professional training. Measurement parameters such as flow rate, pressure, and temperature can be directly read from the meter head without the need for conversion;

　　⑨ Just need to replace the battery regularly(Micro power consumption)'>And the parameters of the tested medium.

Introduction to Flow Meter Knowledge

Flow meters are instruments whose performance strongly depends on changes in usage conditions. In the actual measurement environment on site, the accuracy of the instrument can be affected by various factors such as the stability of the measuring medium, pressure, and bubble content. Therefore, the diversity of measuring media also determines the diversity of flow meters.

However, overall, from the perspective of measurement principles, it can be divided into three types: area equation (velocity equation), volume equation, and mass equation. In terms of product form, the main flow products currently include differential pressure, electromagnetic, vortex street, mass, ultrasonic, volume, rotor, etc10Multiple ways.

2Market growth of flow meters:

according toMIRThe research, although2008The economic environment in the fourth quarter of the year was sluggish, but08For the whole year, the flow meter industry remains stable8.4%The growth. Order amount from2007year31Billion RMB Growth to2008Annual agreement34Billions of RMB.

The growth rate of traditional instruments (throttling, volumetric, turbine, rotor flowmeter, etc.) has significantly slowed down,2008The annual growth rate is4.8%And new instruments (electromagnetic, ultrasonic, vortex street, Coriolis mass flowmeter)2008Annual average growth rate of10%Especially the growth rate of Coriolis mass flow meters and electromagnetic flow meters10%The above.

From the current market development, the growth rate of traditional instruments has significantly slowed down, such as low-end throttling devices with low technical barriers. There are many domestic manufacturers that can produce them, and price competition is fierce, resulting in weak sales growth.

The ultrasonic flowmeter market has grown rapidly in recent years; Compared with throttling devices, the range ratio of turbines can reach up to10：1Moreover, it is relatively accurate and still favored by small and medium-sized customers in trade settlement; Electromagnetic flowmeter is the fastest developing instrument, which has a wide range of applications due to the lack of intermediate components and ease of maintenance.

With the development of flow meter technology, new instruments are replacing traditional instruments in many fields, which is a general development trend, but the process will be long.

（1）.Electromagnetic flowmeter: From the perspective of electromagnetic flowmeter products themselves, electromagnetic flowmeter is a mature product. With the development of technology in recent years, on the one hand, the intelligence of electromagnetic flowmeter transmitters has been enhanced, and converters have added functions such as self diagnosis and self calibration. Thus achieving some online self diagnostic functions, reducing the maintenance workload of electromagnetic flow meters, and replacing traditional offline inspection methods with online inspection.

（2）.Vortex flowmeter: The biggest challenge in the development of vortex flowmeter technology is how to resist the noise and vibration issues encountered in practical production. The vortex flowmeter is still a developing flowmeter, and its theoretical foundation and practical experience are still relatively poor. In the coming years, with the continuous maturity of vortex flowmeter technology and the gradual improvement of user acceptance and technical level, vortex flowmeters will gradually be maturely applied.

（3）.Mass flow meter: Unlike electromagnetic and vortex flow meters, mass flow meters have a higher technical threshold. The biggest obstacle to expanding the application of quality flow meters is the issue of price. In the decades since the development of quality flow meters, local suppliers have never had a specific grasp of the production technology of quality flow meters. Therefore, the price of quality flow meters remains high, except for their widespread application in the petroleum and petrochemical industry, they are less commonly used in other industries due to price restrictions. At present, mainstream quality flow meter suppliers abroad have also seen such market demand and begun to promote low-end quality flow meter products in the market. From the perspective of mass flow meter technology, the diameter of mass flow meters is also increasing, and they can be used on various large-diameter pipelines

How to convert glass rotor flowmeter when measuring different gases?

;A glass rotor flowmeter with air as the measuring medium is introduced with nitrogen and ammonia decomposition gases, respectively,Is the actual traffic the same as the displayed traffic?How to convert different words?

The actual traffic is different from the displayed traffic. There is a conversion formula, I will copy it to you tomorrow.

Q1=Q2×SQR((p2×T1)/(p1×T2))×SQR(B1/B2)

Q1Convert the actual flow rate under working conditions to the flow rate under standard conditionsNm3/h

Q2Convert the actual flow rate in the inspection state to the flow rate in the standard stateNm3/h

p1Absolute pressure under inspection statusmmH2O(Usually at one atmosphere pressure10333mmH2O)

p2Absolute pressure under working conditionsmmH2O

T1Absolute temperature in inspection stateK(Usually)293K）

T2Absolute temperature under working conditionsK

B1Test the density of the medium under standard conditionskg/Nm3(usually air density)

B2Density of the tested medium in standard statekg/Nm3

SQR stands for root sign