Spare parts MANNFILTER C1337

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Magnetic circuit system: Its function is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented using magnets, which has the advantages of a relatively simple structure and less interference from AC magnetic fields. However, it can easily polarize the electrolyte liquid inside the measuring tube, causing the positive electrode to be surrounded by negative ions and the negative electrode to be surrounded by positive ions, resulting in electrode polarization and an increase in internal resistance between the two electrodes, which seriously affects the normal operation of the instrument. When the diameter of the pipeline is large, the magnet is also large, bulky, and uneconomical. Therefore, electromagnetic flow meters generally use alternating magnetic fields and are excited by a 50HZ power supply.

Measurement catheter: Its function is to allow the measured conductive liquid to pass through. In order to divert or short-circuit the magnetic flux when the magnetic field lines pass through the measuring conduit, the measuring conduit must be made of non-magnetic, low conductivity, low thermal conductivity, and materials with certain mechanical strength, such as non-magnetic stainless steel, fiberglass, high-strength plastic, aluminum, etc.

Electrode: Its function is to generate an induced potential signal proportional to the measured value. The electrode is generally made of non-magnetic stainless steel and is required to be flush with the lining so that fluid can pass through without obstruction. Its installation position should be in the vertical direction of the pipeline to prevent sediment from accumulating on it and affecting measurement accuracy.

Shell: Made of ferromagnetic material, it is the outer shell of the distribution system excitation coil and isolates the interference of external magnetic fields.

Spare parts MANNFILTER C1337

Spare parts MANNFILTER C1337

Lining: There is a complete layer of electrical insulation lining on the inner side of the measuring conduit and the flange sealing surface. It directly contacts the liquid being measured, and its function is to increase the corrosion resistance of the measuring conduit and prevent the induced potential from being short circuited by the metal measuring conduit wall. The lining materials are mostly corrosion-resistant, high-temperature resistant, wear-resistant polytetrafluoroethylene plastics, ceramics, etc.

Converter: The induced potential signal generated by liquid flow is very weak and greatly affected by various interference factors. The function of the converter is to amplify and convert the induced potential signal into a unified standard signal and suppress the main interference signal. Its task is to amplify and convert the induced potential signal Ex detected by the electrode into a unified standard DC signal.

characteristic

1. Measurement is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity;

2. Measure the flow components inside the tube, with no pressure loss and low requirements for straight pipe sections. Adaptability to slurry measurement;

3. Reasonably selecting sensor lining and electrode materials, which have good corrosion resistance and wear resistance;

4. The converter adopts a novel excitation method, with low power consumption, stable zero point, and high accuracy. The flow range can reach 150:1;

5. The converter can be integrated or separated from the sensor;

6. The converter adopts a 16 bit high-performance microprocessor, 2x16 LCD display, convenient parameter setting, and reliable programming;

7. The flowmeter is a bidirectional measurement system equipped with three integrators: forward total, reverse total, and differential total; It can display positive and negative flow rates and has multiple outputs: current, pulse, digital communication HART；

8. The converter adopts surface mount technology (SMT) and has self checking and self diagnostic functions;

9. The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity. The sensor's induced voltage signal is linearly related to the average flow rate, resulting in high measurement accuracy.

10. There is no obstruction in the measuring pipeline, so there is no additional pressure loss; There are no movable parts inside the measuring pipeline, so the sensor has an extremely long lifespan.

11. Due to the fact that the induced voltage signal is formed in the entire space filled with a magnetic field and is the average value on the surface of the pipeline, the sensor requires a shorter straight pipe section, with a length of 5 times the diameter of the pipeline.

12. The converter adopts the latest international microcontroller (MCU) and surface mount technology (SMT), with reliable performance, high accuracy, low power consumption, stable zero point, and convenient parameter setting. Click on the Chinese display LCD to show cumulative flow, instantaneous flow, flow rate, flow percentage, etc.

13. A bidirectional measurement system that can measure both forward and reverse flow rates. Using special production processes and high-quality materials to ensure the stability of product performance over a long period of time.

Classification

According to the different types of external magnetic fields, there are mainly two types of electromagnetic flow meters: DC type and induction type. The external constant lower magnetic field B of the DC electromagnetic flowmeter (Figure 2) is perpendicular to the tube axis, and two electrodes are installed at positions C and D to measure the electromotive force U induced by the fluid crossing the magnetic field. The flow rate Q can be calculated using the following formula:

Magnetic circuit system: Its function is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented using magnets, which has the advantages of a relatively simple structure and less interference from AC magnetic fields. However, it can easily polarize the electrolyte liquid inside the measuring tube, causing the positive electrode to be surrounded by negative ions and the negative electrode to be surrounded by positive ions, resulting in electrode polarization and an increase in internal resistance between the two electrodes, which seriously affects the normal operation of the instrument. When the diameter of the pipeline is large, the magnet is also large, bulky, and uneconomical. Therefore, electromagnetic flow meters generally use alternating magnetic fields and are excited by a 50HZ power supply.

Measurement catheter: Its function is to allow the measured conductive liquid to pass through. In order to divert or short-circuit the magnetic flux when the magnetic field lines pass through the measuring conduit, the measuring conduit must be made of non-magnetic, low conductivity, low thermal conductivity, and materials with certain mechanical strength, such as non-magnetic stainless steel, fiberglass, high-strength plastic, aluminum, etc.

Electrode: Its function is to generate an induced potential signal proportional to the measured value. The electrode is generally made of non-magnetic stainless steel and is required to be flush with the lining so that fluid can pass through without obstruction. Its installation position should be in the vertical direction of the pipeline to prevent sediment from accumulating on it and affecting measurement accuracy.

Shell: Made of ferromagnetic material, it is the outer shell of the distribution system excitation coil and isolates the interference of external magnetic fields.

Lining: There is a complete layer of electrical insulation lining on the inner side of the measuring conduit and the flange sealing surface. It directly contacts the measured liquid and its function is to increase the corrosion resistance of the measuring conduit, preventing the induced potential from being short circuited by the metal measuring conduit wall. The lining materials are mostly corrosion-resistant, high-temperature resistant, wear-resistant polytetrafluoroethylene plastics, ceramics, etc.

Converter: The induced potential signal generated by liquid flow is very weak and greatly affected by various interference factors. The function of the converter is to amplify and convert the induced potential signal into a unified standard signal and suppress the main interference signal. Its task is to amplify and convert the induced potential signal Ex detected by the electrode into a unified standard DC signal.

characteristic

1. Measurement is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity;

2. Measure the flow components inside the tube, with no pressure loss and low requirements for straight pipe sections. Adaptability to slurry measurement;

3. Reasonably selecting sensor lining and electrode materials, which have good corrosion resistance and wear resistance;

4. The converter adopts a novel excitation method, with low power consumption, stable zero point, and high accuracy. The flow range can reach 150:1;

5. The converter can be integrated or separated from the sensor;

6. The converter adopts a 16 bit high-performance microprocessor, 2x16 LCD display, convenient parameter setting, and reliable programming;

7. The flowmeter is a bidirectional measurement system equipped with three integrators: forward total, reverse total, and differential total; It can display positive and negative flow rates and has multiple outputs: current, pulse, digital communication HART；

8. The converter adopts surface mount technology (SMT) and has self checking and self diagnostic functions;

9. The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity. The sensor's induced voltage signal is linearly related to the average flow rate, resulting in high measurement accuracy.

10. There is no obstruction in the measuring pipeline, so there is no additional pressure loss; There are no movable parts inside the measuring pipeline, so the sensor has an extremely long lifespan.

11. Due to the fact that the induced voltage signal is formed in the entire space filled with a magnetic field and is the average value on the surface of the pipeline, the sensor requires a shorter straight pipe section, with a length of 5 times the diameter of the pipeline.

12. The converter adopts the latest international microcontroller (MCU) and surface mount technology (SMT), with reliable performance, high accuracy, low power consumption, stable zero point, and convenient parameter setting. Click on the Chinese display LCD to show cumulative flow, instantaneous flow, flow rate, flow percentage, etc.

13. A bidirectional measurement system that can measure both forward and reverse flow rates. Using special production processes and high-quality materials to ensure the stability of product performance over a long period of time.

Classification

2) Determine the electrode material based on the properties of the dielectric material learned

Attention The company generally provides four types of electrodes: stainless steel, Hastelloy, titanium, and tantalum. The selection of which electrode should be based on the properties of the medium and relevant information manuals

(2) Determine whether to use rubber or PTFE lining based on the temperature of the medium learned (to be determined by the marketer)

Attention: The temperature resistance of rubber should not exceed 80C;

PTFE can withstand a temperature of 150C and can instantly withstand 180C;

Urban sewage can generally be treated with rubber lining and stainless steel electrodes

(3) Based on the learned medium pressure, select the flange specification for the body (to be determined by the marketer)

Attention: The specification of electromagnetic flanges is usually that when the diameter ranges from DN10 to 250, the rated pressure of the flange is ≤ 1.6Mpa;

When the diameter ranges from DN250 to 1000, the rated pressure of the flange is ≤ 1.0Mpa;

When the actual pressure of the medium is higher than the corresponding range of pipe diameter pressure mentioned above, it is a special order, but the maximum pressure shall not exceed 6.4Mpa

(4) Determine the conductivity of the medium

Attention: (1) The conductivity of the electromagnetic flowmeter shall not be lower than 5uS/cm

(2) The conductivity of tap water is about tens to hundreds of uS/cm. Generally, boiler soft water (deionized water) is conductive, while pure water (highly distilled water) is non-conductive

(3) The conductivity of gases, oils, and the vast majority of organic liquids is much lower than 5uS/cm, making them non-conductive.

3. Understand user requirements

(1) Understand whether it is a combination type on-site display or a split type remote transmission display (provided by the user)

Attention: When displaying for split remote transmission, please be aware of the maximum distance. The maximum separation distance is 100 meters

(2) Understand if additional features are needed (provided by the user)

Attention: 1. The electromagnetic flowmeter itself has upper and lower limit flow alarm, frequency and current output functions, and does not require special ordering

2. The sealing protection level of the electromagnetic flowmeter housing is IP65 and IP68. When choosing the submersible IP68, it is a special order

3. When the electromagnetic flowmeter needs to be connected to a computer, an RS-485 communication port needs to be added, which is a special order

4. Selection: After the above steps, the model and specifications of the electromagnetic flowmeter can be finally determined.

Usage

The electromagnetic flowmeter has two operating states: automatic measurement state and parameter setting state.

When the instrument is powered on, it automatically enters the measurement state. In automatic measurement mode, the electromagnetic flowmeter automatically completes various measurement functions and displays corresponding measurement data. In the parameter setting state, the user uses four panel keys to complete the instrument parameter setting.

1. Key function

Key function in automatic measurement mode

Down key

Loop through the selection screen to display the content below

Up key

Cycle to select the content displayed on the screen

Composite key+confirm key

Enter parameter setting state

confirm button

Return to automatic measurement status

Adjustment of LCD display contrast in measurement state: The small LCD is adjusted by pressing the "composite key+up key" or "composite key+down key" for a few seconds; The large LCD is achieved by adjusting the potentiometer on the back of the large LCD.

Key function in parameter setting state

Down key

Subtract 1 from the number at the cursor

Up key

Add 1 to the number at the cursor

Composite key+down key

Move the cursor to the left

Composite key+up key

Move the cursor to the right

confirm button

Enter/Exit submenu

confirm button

Press continuously for two seconds in any state to return to automatic measurement mode

Note: When using the "composite key", you should first press the composite key and then simultaneously hold down the "up key" or "down key"

2. In the parameter setting state, if there is no button operation within 3 minutes, the instrument will automatically return to the measurement state.

3. The flow direction selection for zero point correction of flow can be switched by moving the cursor to the leftmost "+" or "-" and using the "up" or "down" keys to make it opposite to the actual flow direction.

4. To select the unit of flow, you can move the cursor to the original displayed flow unit in the "Flow Range Setting" menu, and then use the "Up" or "Down" keys to switch to meet your needs.

2. Parameter setting function key operation

To set or modify the parameters of an electromagnetic flowmeter, it is necessary to transition the flowmeter from the measurement state to the parameter setting state. In the measurement state, press the "composite key+confirm key" to display the state transition password (0000). According to the confidentiality level, modify the password provided by the manufacturer accordingly. After pressing the "composite key+confirm key" again, it will enter the desired parameter setting state.

Installation of Intelligent Electromagnetic Flow Meter Sensor on Process Pipeline

1. The intelligent electromagnetic flowmeter blockage tube must be filled with medium at any time and cannot work normally without filling or emptying the tube. When the medium is not fully filled in the pipe, the method of raising the height of the outlet pipe at the back of the flowmeter can be used to fill the pipe with the medium, avoiding the incomplete pipe and gas from adhering to the electrode.

2. Vacuum inside the pipeline can damage the lining of the flowmeter, so special attention should be paid.

3. The positive direction of flow should be consistent with the positive direction indicated by the arrow on the flowmeter.

4. The intelligent electromagnetic flowmeter can be installed on straight pipelines, as well as on horizontal or inclined pipelines, but it requires that the center line of the two electrodes be in a horizontal state.

5. For liquid and solid two-phase fluids, it is best to use vertical installation to allow the measured medium to flow from top to bottom, which can evenly wear the lining of the flowmeter and extend its service life.

6. Ensure that there is sufficient space near the pipeline flange for the installation and maintenance of the flowmeter.

If there is vibration in the measuring pipeline, there should be fixed supports on both sides of the flowmeter.

8. If the measuring medium is a heavily polluted liquid, a flowmeter body can be installed in the bypass pipeline without interrupting the process operation, which can be emptied and cleared.

9. When installing a flow meter with PTFE lining, the bolts connecting the flange should be tightened evenly, otherwise it is easy to crush the PTFE lining. It is best to use a torque wrench.

Instrument installation

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method

Simply put, an electromagnetic flowmeter is composed of a flow sensor transmitter. The installation requirement of electromagnetic flowmeter is to be installed at the point of the pipeline or the vertical section of the pipeline, but it must be installed when the pipeline is full. The requirement for the straight pipe section is the first 5D and then 3D, so as to ensure the use of electromagnetic flowmeter and the accuracy requirements.

The measurement principle of electromagnetic flowmeter does not depend on the characteristics of flow rate. If there is a certain amount of turbulence and vortex generated in the non measurement area of the pipeline (such as bends, tangential flow restrictions, or partially open shut-off valves upstream), it is irrelevant to the measurement. If there is a steady-state eddy current in the measurement area, it will affect the stability and accuracy of the measurement. In this case, some measures should be taken to stabilize the flow velocity distribution:

1. Increase the length of the front and rear straight pipe sections

2. Adopt a traffic stabilizer

3. Reduce the cross-section of measurement points.

1. Requirements for the external environment

1.1. Flow meters should be avoided from being installed in places with large temperature changes or high temperature radiation from equipment. If installation is necessary, insulation and ventilation measures must be taken.

1.2. It is best to install the flowmeter indoors. If it must be installed outdoors, it should be protected from rainwater, waterlogging, and direct sunlight. Moisture and sun protection measures should be taken.

1.3. Flow meters should be avoided from being installed in environments containing corrosive gases, and ventilation measures must be taken when installation is necessary.

1.4. For the convenience of installation, maintenance, and upkeep, there should be ample installation space around the flowmeter.

1.5. The installation site of the flowmeter should avoid magnetic fields and strong vibration sources. If the pipeline vibration is large, there should be fixed pipe supports on both sides of the flowmeter.

1. 2. Pipeline electromagnetic flowmeter

2.1. Requirements for straight sections

In order to improve the effects of eddy currents and flow field distortions, there are certain requirements for the length of the straight pipe sections before and after the installation of the flowmeter, otherwise it will affect the measurement accuracy (rectifiers can also be installed, avoiding installation near the regulating valve and half open valve as much as possible).

2.2. Requirements for process pipes

The flowmeter has certain requirements for the upstream and downstream process pipes of the installation point, otherwise it will affect the measurement accuracy.

a. The inner diameter of the upstream and downstream process pipes should be the same as that of the sensor, and should meet the requirement of 0.98DN ≤ D ≤ 1.05DN (where DN is the inner diameter of the sensor and D is the inner diameter of the process pipe)

b. The process pipe and sensor must be concentric, and the coaxial deviation should not exceed 0.05DN

2.3. Requirements for bypass pipes

For the convenience of repairing flow meters, it is best to install a bypass pipe for the flow meter. In addition, for heavily polluted fluids and flow meters that need to be cleaned but cannot be stopped, a bypass pipe must be installed.

a. Convenient maintenance of flow meters

b. Heavy pollution fluids must be installed

c. The fluid cannot stop and the flow meter needs to be cleaned

3. Installation requirements for plug-in electromagnetic flowmeter

3.1. Requirements for straight pipe sections

Inlet/outlet straight pipe section: The inlet should be ≥ 10 × DN; the outlet should be ≥ 5 × DN

3.2. Requirements for docking location

In order to ensure the reliable operation of the instrument, improve measurement accuracy, and avoid interference from external parasitic potentials, the sensor should have a good grounding resistance of less than 10. (If the metal pipeline is well grounded, there is no need to set up a dedicated grounding device.) 3.3 The installation position requirements are shown in the figure

The insertion of electromagnetic flow meters varies depending on the on-site pipeline conditions. Flow meters without ball valves should be installed on pipelines without pressure (i.e. flow meters without ball valves can be selected for installation without pressure). A hole with a diameter of 50 should be opened on the pipeline, and the connecting welded pipe should be welded to the opening of the pipeline; For situations that require continuous loading and unloading or do not allow medium overflow, ball valves must be installed, that is, plug-in electromagnetic flow meters with ball valve structures should be selected; Drill a hole with a diameter of 50 on the pipeline and prepare to weld the connecting welded pipe onto the opening of the pipeline.

Selection of plug-in electromagnetic flowmeter

measurement range

Recommended usage scope

Continuous adjustable from 0.5m/s to 10m/s

Maximum usage range

0.2m/s~15m/s continuously adjustable

signal output

The switch value can be set to

Pulse output (up to 1000Hz)

High/low traffic alarm

air traffic control alarm

Flow direction indication

Fault Alarm

current output

4-20mA output

Configuration method

On site configuration through three manual keys

On site configuration through remote control

On site configuration through a handheld device

memory

EEPROM is a memory that does not disappear and does not require battery storage

explanation

Electromagnetic flow meters are widely used in various fields such as sewage, fluorine chemical industry, production water, tap water industry, as well as pharmaceuticals, steel and many others. Due to its principle, it can only measure conductive liquids. Although it is much better in reliability and stability than other types of flow meters, customers still encounter some problems during actual use. Below, I will explain in detail the selection and installation of electromagnetic flow meters:

1、 Like other flow meters, although the measurement range ratio of electromagnetic flow meters is 30:1, which is higher than vortex flow meters and differential pressure flow meters, it is also limited. Many customers often compare it with water meters when ordering a meter, thinking that it can measure very low flow rates. Generally, it can only measure 0.1m/s. Below this flow rate, electromagnetic flow meters are difficult to measure correctly. So in the initial stage of ordering, it is necessary to clarify the flow range. When placing an order, it is not advisable to order according to the original pipe diameter. It is better to determine the instrument diameter based on your actual flow rate.

2、 Like other flow meters, electromagnetic flow meters also have requirements for straight pipelines before and after installation, although the requirements are lower than other types of flow meters. However, the most crucial point is to meet the requirement of full pipe and then full pipe. Insufficient flow can easily cause the flowmeter to jump:

3、 Like other flow meters, electromagnetic flow meters also have protection levels. Generally, the protection level for integrated flow meters is IP65, and for split type flow meters (for sensors) it is IP68. If customers have requirements for the installation environment of the instrument and the installation location is in underground manholes or other humid places, it is recommended that customers choose split type flow meters. To avoid selecting the wrong one and causing damage to the instrument.

4、 Electromagnetic flow meters can measure corrosive liquids, but in the initial stage of ordering, customers need to provide the correct properties of other measuring media to avoid errors in electrode selection during selection, which may result in the sensor being scrapped during later use, causing inconvenience and economic losses to customers.

5、 Although electromagnetic flow meters have good reliability and are generally not damaged, due to their principle, the sensor electrode surface is always in contact with the liquid, and over time, the electrode surface is more susceptible to contamination. Therefore, in general, for electromagnetic flowmeters, if customers have the conditions to disassemble them, it is recommended to remove and clean the electrodes once every one to one and a half years to ensure the measurement accuracy of the entire flowmeter. Any instrument requires maintenance, and electromagnetic flow meters are no exception.

6、 When the main pipeline is a vertical pipeline, it is generally required that the water flow should be from bottom to top, and should not be from top to bottom as much as possible. The latter can easily cause significant fluctuations in traffic. In addition to filling the pipes, this is also very important for installation, followed by the distance between the front and rear straight pipes.

Choose a place that is easy to maintain and has convenient activities. The flowmeter should be installed at the rear end of the water pump and must not be installed on the suction side; The valve should be installed on the downstream side of the flow.

working principle

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Electromagnetic flowmeter is a flowmeter that measures flow based on Faraday's law of electromagnetic induction. The advantages of electromagnetic flowmeter are minimal pressure loss and a wide range of measurable flow rates. The ratio of maximum flow rate to minimum flow rate is generally above 20:1, suitable for a wide range of industrial pipe diameters, up to 3m. The output signal is linear with the measured flow rate, with high accuracy. It can measure the fluid flow rate of acid, alkali, salt solutions, water, sewage, corrosive liquids, as well as mud, slurry, pulp, etc. with conductivity ≥ 5 μ s/cm. But it cannot measure the flow of gas, steam, and purified water.

When a conductor cuts magnetic field lines in a magnetic field, an induced potential is generated in the conductor, and the magnitude of the induced potential is proportional to the effective length of the conductor in the magnetic field and the speed at which the conductor moves perpendicular to the direction of the magnetic field. Similarly, when a conductive fluid flows vertically in a magnetic field and cuts magnetic induction lines, it will also generate induced potentials on the electrodes on both sides of the pipeline. The direction of induced potential is determined by the right-hand rule, and the magnitude of induced potential is determined by the following equation:

Ex=BDv ---------------- Equation (1)

In the formula, Ex represents the induced potential, V；

B - Magnetic induction intensity, T

D - Inner diameter of pipeline, m

V - average flow velocity of the liquid, m/s

However, the volumetric flow rate qv is equal to the product of the fluid velocity v and the pipeline cross-sectional area (π D ²)/4. Substituting equation (1) into this equation yields:

Qv=(πD/4B)* Ex --------- 式（2）

As can be seen from the above equation, when the diameter D of the pipeline is fixed and the magnetic induction intensity B remains constant, the measured volume flow rate is linearly related to the induced potential. If an electrode is inserted on each side of the pipeline, an induced potential Ex can be introduced, and the magnitude of this potential can be measured to obtain the volumetric flow rate.

According to Faraday's principle of electromagnetic induction, a pair of detection electrodes are installed on the tube wall perpendicular to the axis of the measuring tube and the magnetic field lines. When the conductive liquid moves along the axis of the measuring tube, it cuts the magnetic field lines and generates an induced potential. This induced potential is detected by the two detection electrodes, and its value is proportional to the flow rate. Its value is:

E=B·V·D·K

In the formula: E - induced potential;

K - coefficient related to magnetic field distribution and axial length;

B - Magnetic induction intensity;

V - average flow velocity of conductive liquid;

D - electrode spacing; (Measuring the inner diameter of the tube)

The sensor uses the induced potential E as a flow signal, which is transmitted to the converter. After signal processing such as amplification, transformation, and filtering, the instantaneous and cumulative flow rates are displayed on a backlit dot matrix liquid crystal display. The converter has 4-20mA output, alarm output and frequency output, and is equipped with communication interfaces such as RS-485, and supports HART and MODBUS protocols.

Note: The parameters of different electromagnetic flow meters may vary slightly. Please be sure to refer to the instruction manual when using them.

According to Faraday's law of electromagnetic induction, in a uniform magnetic field with a magnetic induction intensity of B, a non-magnetic pipeline with an inner diameter of D is placed perpendicular to the direction of the magnetic field. When a conductive liquid flows in the pipeline at a flow velocity v, the conductive fluid cuts the magnetic field lines If a pair of electrodes are installed at both ends perpendicular to the diameter of the magnetic field on the cross-section of the pipeline, it can be proven that as long as the flow velocity distribution inside the pipeline is axisymmetric, an induced electromotive force is generated between the two electrodes:

e=KBDv (3-36)

In the equation, v is the average flow velocity on the pipeline section, and k is the instrument constant. The volumetric flow rate of the pipeline can be obtained as follows:

qv= πeD/4KB (3-37)

As can be seen from the above equation, the volumetric flow rate qv is linearly related to the induced electromotive force e and the inner diameter D of the measuring tube, inversely proportional to the magnetic induction intensity B of the magnetic field, and independent of other physical parameters. This is the measurement principle of electromagnetic flowmeter.

It should be noted that in order for equation (3-37) to strictly hold, the measurement conditions of the electromagnetic flowmeter must satisfy the following assumptions:

① Magnetic field is a uniformly distributed constant magnetic field;

② The axisymmetric distribution of flow velocity of the measured fluid;

③ The tested liquid is non-magnetic;

④ The conductivity of the tested liquid is uniform and isotropic.

Technical Requirements

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accuracy class

The accuracy level and maximum allowable error of the flowmeter within the specified flow range shall comply with the provisions of Table 1. Flow meter error refers to the relative indication error.

Accuracy level and maximum allowable error

accuracy class

0.2

（0.25）

（0.3）

0.5

Maximum allowable error

±0.2%

（±0.25%）

（±0.3%）

±0.5%

accuracy class

1.0

1.5

2.5

/

Maximum allowable error

±1.0%

±1.5%

±2.5%

/

Note: Priority should be given to using grades without parentheses

reference error

For the error representation of flow meters used for instantaneous flow indication, reference error can also be used, and the maximum allowable error series should comply with the provisions of Table 1. The accuracy level is no longer given in the calibration results of the bid, but the maximum allowable error representation should be used, and FS should be marked after the maximum allowable error, such as ± 0.5% FS.

In the calibration of a flowmeter, the error representation method of the flowmeter should be given according to one of the accuracy level and reference error; For flow meters that use a combination of relative indication error and reference error to represent errors, a unified method should also be used to represent their errors during a single calibration.

repetitiveness

The repeatability of the flowmeter shall not exceed one-third of the maximum allowable absolute error specified for the corresponding accuracy level.

measurement range

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Electromagnetic flow meters have a wide measurement range, usually from 20:1 to 50:1, with a wide optional flow range; The aperture range of electromagnetic flow meters is wider than other types of flow meters, ranging from a few millimeters to 3 meters; It can measure both positive and negative flow rates, as well as pulsating flow rates, as long as the pulsating frequency is much lower than the excitation frequency; The instrument output is essentially linear; Easy to choose material varieties for fluid contact parts, and can be applied to corrosive fluids and other advantages. Due to the fact that electromagnetic flow meters have a much higher chance of measuring suspended solids or pollutants compared to other flow meters, the probability of failure caused by the adhesion layer on the inner wall is relatively high. If the conductivity of the adhesion layer is similar to that of the liquid, the instrument can still output signals normally, but only change the flow area, resulting in an implicit fault of measurement error; If there is a high conductivity adhesion layer, the electromotive force between the electrodes will be short circuited; If it is an insulating adhesive layer, the electrode surface will be insulated and the measurement circuit will be disconnected. Both of the latter two phenomena will cause the instrument to malfunction. [1]

Main products

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The intelligent electromagnetic flowmeter adopts a backlit wide temperature dot matrix LCD display, all displays are in Chinese, with multiple and practical functions, especially convenient for users to operate, reducing unnecessary trouble and errors.

Fast delivery, low cost, and easy maintenance.

How does an electromagnetic flowmeter resist interference?

When measuring large interference signals such as pulp/slurry, using the 8707 high signal flow tube can improve signal strength

The intelligent electromagnetic flowmeter AFLD is designed based on the principle of full intelligence, and there are significant differences in measurement accuracy, functionality, reliability, and service life compared to old-fashioned or fake intelligent electromagnetic flowmeters produced by some domestic enterprises.

The service life of electromagnetic flow meters should be over 10-20 years, so we fully consider this when designing. We are very careful in every detail from sensors to converters, from design, material selection, process, production, testing, etc. We pay great attention to every link and design customized production lines for specialized and electromagnetic flow meters in China to ensure the long-term quality of our products.

The plug-in electromagnetic flowmeter is composed of a plug-in electromagnetic flow sensor (referred to as the sensor) and an electromagnetic flow converter (referred to as the converter). It is an instrument used to measure the volumetric flow rate of various conductive liquids inside pipelines. Insertion type electromagnetic flowmeter is used to measure the flow rate of conductive fluids in sectors such as tap water, steel, petroleum, chemical, power, industry, and water conservancy. It can also measure corrosive conductive liquids such as acids, alkalis, and salts.

Precautions

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1. The accuracy level and function of the instrument are selected based on measurement requirements and usage scenarios to achieve cost-effectiveness. For example, in situations such as trade settlement, product handover, and energy measurement, higher accuracy levels such as 1.0, 0.5, or higher should be selected; For process control applications, choose different accuracy levels according to control requirements; In some cases where only the process flow rate needs to be detected without precise control and measurement, a slightly lower accuracy level, such as 1.5, 2.5, or even 4.0, can be selected. In this case, a low-cost plug-in electromagnetic flowmeter can be used.

2. When measuring medium flow rate, instrument range, and caliber, the full flow rate of an electromagnetic flowmeter can be selected within the range of 0.5-12m/s for measuring medium flow rate, which is relatively wide. The selection of instrument specifications (caliber) may not necessarily be the same as the process pipeline, and should be determined based on whether the measured flow range is within the flow rate range. That is, when the pipeline flow rate is too low to meet the requirements of the flow instrument or the measurement accuracy cannot be guaranteed at this flow rate, the instrument port diameter needs to be reduced to increase the flow rate inside the pipeline and obtain satisfactory measurement results.

3. Try to avoid ferromagnetic objects and equipment with strong electromagnetic fields as much as possible to prevent the magnetic field from affecting the working magnetic field and flow signal of the sensor.

4. It should be installed in a dry and ventilated place as much as possible, avoiding direct sunlight and rain. The ambient temperature should be between -20 and+60 ℃, and the relative humidity should be less than 85%.

5. There should be ample space around the flowmeter for easy detection and maintenance.

routine maintenance

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Just need to conduct periodic visual inspections of the instrument, check the surrounding environment of the instrument, remove dust and dirt, ensure that there is no water or other substances, check if the wiring is good, and check if there are any newly installed strong electromagnetic field devices or wires crossing the instrument near the instrument. If the measuring medium is prone to contaminating the electrode or settling or scaling inside the measuring tube wall, regular cleaning and cleaning should be carried out.

Fault finding

If the flowmeter is found to be malfunctioning after being put into operation or after a period of normal operation, the external condition of the flowmeter should be checked first, such as whether the power supply is good, whether the pipeline is leaking or in a non full state, whether there are bubbles in the pipeline, whether the signal cable is damaged, and whether the output signal of the converter (i.e. the input circuit of the rear instrument) is open circuit. Remember to blindly disassemble and repair the flowmeter.

Sensor inspection

Testing equipment: one 500M Ω insulation resistance tester and one multimeter.

Test steps:

(1) When the pipeline is filled with medium, use a multimeter to measure the resistance between terminals A, B, and C. The resistance between A-C and B-C should be equal. If the difference is more than 1 times, it may be due to electrode leakage, condensation on the outer wall of the measuring tube or inside the junction box.

(2) Measure the insulation resistance between A-C and B-C with an M Ω meter when the lining is dry (it should be greater than 200M Ω). Use a multimeter to measure the resistance between terminals A and B and the two electrodes inside the measuring tube (which should be in a short-circuit connected state). If the insulation resistance is very low, it indicates electrode leakage and the entire flowmeter should be returned to the factory for repair. If the insulation has decreased but still exceeds 50M Ω and the inspection result in step (1) is normal, it may be due to moisture on the outer wall of the measuring tube, and a hot air blower can be used to dry the inside of the shell.

(3) Measure the resistance between X and Y with a multimeter. If it exceeds 200 Ω, the excitation coil and its lead may have an open circuit or poor contact. Remove the terminal board for inspection.

(4) Check the insulation resistance between X, Y, and C, which should be above 200M Ω. If there is a decrease, dry the inside of the shell with hot air. During actual operation, the decrease in coil insulation will lead to increased measurement errors and unstable instrument output signals.

(5) If it is determined that the sensor has a fault, please contact the electromagnetic flowmeter manufacturer. Generally, it cannot be solved on site and needs to be repaired by the manufacturer.

Converter inspection

If it is determined to be a converter fault and there is no problem with the external cause after inspection, please contact the electromagnetic flowmeter manufacturer. The manufacturer usually solves the problem by replacing the circuit board.

Maintenance of electrodes

Before using an electromagnetic flowmeter, it is necessary to calibrate it with a standard pH solution. After calibration, before operation, everyone must pay attention to cleaning the electrodes of the electromagnetic flowmeter with distilled water first, and then cleaning the electrodes again with measuring solution.

If the electromagnetic flowmeter is not used, when removing the electrode of the electromagnetic flowmeter, everyone should be careful not to let the tactile sensor of the electrode collide with a hard object, otherwise any damage will affect the use of the electrode.

After using the electromagnetic flowmeter, everyone should put the electrode of the electromagnetic flowmeter on the sleeve and put less saturated solution inside. As long as the electrode bubbles are moist, it is enough, but remember not to soak them in distilled water.

4. It is important to keep the electrodes clean and avoid short circuits on both sides of the output, as this may result in inaccurate measurements and affect the use of the electromagnetic flowmeter.

In fact, there are many methods to maintain the electrodes of an electromagnetic flowmeter. Everyone should pay more attention during use and not let their small negligence cause the electromagnetic flowmeter to malfunction in the future.

Fault Analysis

1. Malfunctions during debugging period

During the debugging phase, faults usually occur during the installation and debugging of instruments. Once eliminated, they will not occur again under the same conditions in the future. Common debugging failures are usually caused by improper installation, environmental interference, and fluid characteristics.

1. Installation aspect

Usually, faults are caused by incorrect installation of electromagnetic flow sensors, such as installing the sensor at the highest point of a piping system that is prone to gas accumulation; Or installed on vertical pipes from top to bottom, which may result in emptying; Or there is no back pressure behind the sensor, and the fluid is directly discharged into the atmosphere, forming a non full tube inside the measuring tube.

1. Environmental aspect

Usually, it is mainly caused by stray current interference in pipelines, strong electromagnetic wave interference in space, and magnetic field interference in large motors. Good separate grounding protection can usually achieve satisfactory results for pipeline stray current interference, but if encountering * stray currents (such as electrolytic workshop pipelines, sometimes the peak AC potential Vpp induced on the two electrodes can be as high as 1V), additional measures need to be taken and the flow sensor needs to be insulated from the pipeline. Space electromagnetic wave interference is generally introduced through signal cables and is usually protected by single-layer or multi-layer shielding.

1. Fluid aspect

The presence of uniformly distributed small bubbles in the measured liquid usually does not affect the normal operation of the electromagnetic flowmeter, but as the bubbles increase

The output signal of the meter will fluctuate. If the bubble is large enough to cover the entire electrode surface, it will cause the electrode circuit to break instantly as the bubble flows through the electrode, resulting in greater fluctuations in the output signal.

When an electromagnetic flowmeter with low-frequency square wave excitation measures a slurry with excessive solid content, it will also generate slurry noise, causing fluctuations in the output signal.

When measuring mixed media, if it enters the flow sensor for measurement before the mixing is uniform, it will also cause fluctuations in the output signal.

Improper selection of electrode materials and the measured medium can also affect normal measurements due to chemical reactions or polarization phenomena. Electrode materials should be selected correctly according to the instrument selection or relevant manuals.

1. Malfunctions during operation

|Brand

series

model

|Product Name

by PROHUB

003020 D40 30/30

PROHUB

120557 D73 2-FACH

PROHUB

002973 LR 085 KL 90

PROHUB

16124-FL

PROHUB

002990 GE 040 KL 90

by PROHUB

| 002909 D60-300

PROHUB

002999 GE 060 KL 120

PROHUB

16123-FL

PROHUB

120557 D73 2- FACH

by PROHUB

003020 D40 30/30

PROHUB

090-060-012F

PROHUB

17213- FL

PROHUB

4035910

by PROHUB

17082B08

PROHUB

PH-Y12 -0002- 1

PROHUB

PH-Y120002-16

PROHUB

PH-Y12-0002- 16A

PROHUB

B0101 14022-3-7

PROHUB

20108-ST

bearing housing

PROHUB

20108CO2

drive shaft

PROHUB

PH-Y12-0002-17

PROHUB

090030007

by PROHUB

003028

PROHUB

20108- KA

|Universal shaft

PROHUB

090010045

Roller assembly

PROHUB

090060020

Bearing assembly

PROHUB

20107-FL

belt

PROHUB

090-060-004

PROHUB

090060021

Bearing assembly

SIBA2021113.20

COGSDILLSRMR-31-03

BRINKMANNBFS 232-KH

EUCHNERCES-A-AEA-04B 072000

WOERNERAB31-14/2-1A2A

ALLEN-BRADLEYVPL-B1303F-PJ12AA

BIJUE ELIMONPVB16A03AAAAAAAA00

JBW404.867.0010 DCK31

FHFFHF21225113

ETAEM12-T01-001-DC24V-4

ZF4152.062.018 PG 500/1

ServicesAG 750 50(￠19*118)

ServicesAFJ 50 038V1(￠50*150)

ServicesAFJ 70 015V1(￠19*72)

JOSTJ0EST-TK5230VAC-5A

SARTORIUSPR6211-11

ROLANDP42AGS P.N.S0002800

AVENTICS0821300856pressure regulating valve

MAIERDXSR 265 K-50rotary joint

AG.70HE652FV50A2R-AC230Vlimit switch

WIXROYD32810.W0001

KTRBOWEX-COUPLING 117038-24-8020

KTRBOWEX-COUPLING M-24

BAUERBF70Z-44/DPE09XB4C-S/ESX027A9/SP

SCHMERSALAZ17/170-B5

SCHMERSALAZ 17-11ZK

SCHUNKINK80/S 0301550

SCHUNKBBCK8758 ID:1328053

CHERRYG84-4400LPBUS-2

TAPPKEMER-MATRIXQWS-7000/4-30-L

RSF ELECTRONICBE4360731129

EWO423.294

EWO334.411

OPTRON3874460

ASC102850 BL25M-U-3-350-B-RF (executed according to nameplate 91236) quotation valid until August 10, 2022

WILDENP.025/PPPPP/WFS/TF/PWF

SCHMERSAL103013814 SLB240-R-1-ST

SCHMERSAL103013806 SLB240-E-1-ST

EATONFAK-S/KC11/I

PILZ777314

EUCHNER082122 NZ1VZ-3131E-M

REMECH17-4132-1122.47

SCHMERSAL1NO+1NC，ZFH232-22

IFMIFS244

IFMIFS240

DatasensorS15-PA-2-C10-PK

BUCHERSDRB-P-10-SM

PREVOSTPPS1 MM2534

MAXON118889+166943

MAXON283858+363974+301212

MAXON283858+144006

PATLITECLF10-24

TRIDH130-00002

GEA4443-0804-020

GEA4443-0804-021

GEA4443-0804-022

GEA4443-0804-023

AUMASA14.1 A101432

JUMO90/00559222

SCHUNK302316 SWK-011-000-000

SCHUNK302317 SWA-011-000-000

SCHUNK9935801 SWO-E10-011-K

SCHUNK9935802 SWO-E10-011-A

SCHUNK302223 A-SWK-011-ISO-A50

LUBRIPLATE LUBRICANTSSFGO ULTRA 32

Buschjost8497277.9668

OTT9560007392

OTT9560148392 ADAPTER PSC 80

D+PDP-K-003-000018 + DP-K-003-000054

BUHLERNT 63-KN-VA-M3/240

BUHLERNT 63-KN-VA-M3/500

BEMERS130-41-22.3

SPECKIVD-360-MK-400V replacement

BRINKMANNBFS238/40-61KBT5Z+415

BALTECP rne 181 HPP ang D 160772 a

BAUMERMDFK 08G2101/0500

Language14570692 MW-XXUS - 0...200 MBAR - 1/4 NPT-F - 1/2 -14 LT

VVCDSLbutterfly valve

ATOSA1Y-HA32B

ATOSSCLI-40317

ATOSSCLI-4033/1

ATOSLIDEW2-4-I10P12A

PROMINENTThe quotation for S1BA S1BAH10050PVTS000M000 is valid until August 13, 2022

CELSADSA12-NS40/P1R-01

GEMU88029346

DINSE62903N0004 1503406

COGSDILLSRMR-31-03

HMSAWB3000

SCHNEIDERATS448C41Q

ASCON TECHNOLOGICXP-3000/99

MAC1353G-611D-3 M0D:AL01solenoid valve

HOFMANN619161 75

HOFMANN656050 1600

HOFMANN647050 55

AVTRONHS40ZT6MG6W903S

STERLINGLPHX 45311 AB

HYDAC0280D005ONfilter element

HYDAC0240D005ONfilter element

HYDAC0030D025Wfilter element

MEISTER45XM1030XG20WH

LOVATOG48111auxiliary contact

KARL STORZTC-302-03G2H39425

GRUNERUL-721Q-R1A-BO32

PULSOTRONIC08430131055 CSK087A-LDR

SARTORIUSPR6211-11

RebsVEG8/7

RebsVEU8/3

RebsVEG6

JOSTJ0EST-TK5230VAC-5A

BOLZEN1259637 5333655

KRIWANSE-E1 347017-10

KRIWANOLC-D1 L=100

PILZ777301

PILZ774314

IFMSBG233

IFMIGT215

IFMOJ5031

E+L00352056-FR 6011

E+L00352034-OL 8221

AVTRONHS40ZT6MG6W903S+5M

TRIDH130-00002

PREVOSTMT RA1063

FORMAT92571015

SCHNEIDERThe quotation for ATV650C31N4F is valid until August 13, 2022

NUMATICSA51BA452CG60S61 24VDC

SCHNEIDERXS618B1MAL2 quotation is valid until August 1, 2022

KUEBLER8.5000.B352.2048

AUTONICSBEN5M-MFRphotoelectric switch

WENGLORCP24MHT80

OLIVER VALVESCHECK VALVE CV75S 316SS,6000PSIcheck valve

PILZ541011

PILZ541012

PILZ541009

RITTALSZ 4140.830

RITTALSZ 4315.800

STARSH736001A0727

SEWMC07B0008-5A3-4-00

RUWAC10003683

RUWAC968001F

RUWACFL-90870A134515D

RUWACFL-90870A234515E

RUWAC35211UL

SOLAHDSTV25K-24S

PREVOSTBAL 2040B

ROLANDNKAS-W DELIVERY LENGTH PER PIECE 10 M

ROLANDA100

ROLANDTN15S SENSOR-WITHOUT CABLE

SCHMALZ10.02.02.04521 SCPI-FS 25 NO RP M12-5 Replacement

GEMU610 12D 1 5 211/N 88015108

ATSSP179 266.70X304.80X17.45 L2M FKMskeleton oil seal

EMETAMA215-12-0060-40

RITTALSK 3214.100

PEWAG4031538 (A46118) RK 1623-1X15.875X9.65 DIN8187 21.15-meter quotation valid until July 29, 2022Roller chain

SCREENVP-3/1.0/P/112/130/1.0

HELUCKELMULTIFLEX 512-PUR 7G1.0，22527

HELUCKELMULTIFLEX 512-C-PUR 5G1.0，22596

RebsVEU 8/3

RebsVEG 8/7

RebsVEG 6

SAACKES060020002 F-OSA

NORDSON1056119 24VDC,5.4W,LED

KYTOLASLM13-F

MASTERWATT75030030D000004

BRONKHORSTM13V14I-AGD-33-K-S

WALTHER1-SP-006-2-WR017-11-2

LEGRIS7883 06 10

LABOMCE6110 A1060H1K1010 T420Pressure transmitter

ROSSEL0-0354-00095-11

ROSSEL0-0355-00079-11

ROSSEL2-7223-00302-11

ROSSEL2-4006-01891-11

ROSSEL2-6003-00142-11

RITTALSZ 4140.830

RITTALSZ 4315.800

IFMECV932

IFMECV933

VEMIE3-W41R 80 G 4 替代

MAYR8225258, up 5% on August 1st

BLACK BOXACU5050A-R2

JUMO8467343

SCHUNK39303313 PZN-PLUS 125-1-V

P+FENI58IL-H10BA5-1024UD1-RC1encoder

P+FENA58IL-S10CA5-1213B17-ABPencoder

P+FENA58IL-S10CA5-0013B17-ABPencoder

G. BEE0020005001020 + 0020005992015 10998916

G. BEE0020005003020 + 0020005992015

G. BEE0020005992015 11447861

PILZ541010

PILZ541060

UNIVERSAL HYDRAULIKSSPA-5/64-A-N-R-V0-01-AX

P+FENI58IL-H10BA5-1024UD1-RC1encoder

AWH390109000 DN40-65

AWH390112000 DN80-100

ANGELUS2257029

HILMA8-2280-8017 SLOT 28 MM -8-2280-801

HILMA8-2280-8017 SLOT 28 MM

8-2280-8017 SLOT 28 MM

PREVOSTCPI 127710E

BRONKHORSTM14V14I-AGD-33-K-S

CCDGLGE CMG80

SCHOENBUCH2997 OTFS162

STRINGRK 86A DN 200, PN 16, BODY 1.4404

GESINTCLS-A

TURCKBKV8240-0/9

EGELG 518 GSP P11237

VECTORVN1630A

VECTORCANCABLE 2Y

TURCKBI3U-EG12SK-AP6X

ASA HYDRAULIK19434 SAE3 2.1/2063 SDKSS063 quotation valid until August 18, 2022

ETASES582.1

HBMCLY41-350/6

ATLAS660-101401 8202-1350-22 quotation valid for 4 weeks

ATLAS660-100213 8202-1220-19

CYTECSTP-090-3

CYTECSTP-090-1

PREVOSTPPS1 BO25

PREVOSTTF 5

PREVOSTPPS1 RSI25

ETASES582

FISCHERDE49C50040BH00MW is technically compatible (inquiry model has been discontinued). The quotation is valid until August 18, 2022

REXROTHR901496443 4WREE 6 E16-3X/V/24F1

REXROTH4WRZ16W6-100-7X/6EG24N9ETK4/M

REXROTHR901071449 H-4WEH25E6X/6EG24N9ETSK4/B10D3

SOLARTRONDP/20/S 5M CABLE

SCHMALZ10.01.06.00891 SAOB 60X30 NBR-60 G1/4-IG

SCHMALZ10.01.06.00852 SAB 60 NBR-60 G1/4-IG

SCHMALZ10.01.06.00670 SAB 40 NBR-60 G1/4-IG

SCHMALZ10.01.03.00298 HTR-UNI 2N G2 80 （或者10.01.03.00299 HTR-UNI 2N G2 140）

SCHMALZSAB_60_NBR_60_G1/4

SCHMALZSAUGER_MIT_HALTER

TRCE65M110-02807

MARPOSS3415335200

MICROSONICMIC+340/IU/TC

VECTOR05075 CANCABLE 2Y

KNOLLSP50-550

VAHLESA-KUFU25/6/14HS1,0/4/6

VOITH7608458,SIZE 487

SIBANH-125A-GL/GG-GR.00-690V

CARLO GAVAZZIEASSM2310S

RESOLVEOPTICS200-001

RESOLVEOPTICS286-000

ACEML 3325 EUM+NM 33+PB 3325 quotation valid until July 26, 2022

ACEML3325-NM33-PB3325

MEGATRONHHI 1710M R5K W5% L0,1%

VAHLE0252490/00

KTRBOWEX KUPPLUNG M-32

KTRBOWEX KUPPLUNG M-24

END ARMATURESRE080303

KNFNB6KTE IP00-T 230V50HZ

FITOKCVSS-FRP8

ECKERLEEIPH2-011 RK03-1X

EISTEIN WORKHTS 600W 230V

VOITHM14*1.5 160C

VOITHM18*1.5 160C 0395/0260

NIVELCORCM-401-3 quotation is valid until July 25, 2022

WARNER5200-452-011

GACHOTV9 - 12 IN. PI T.GAZ TFM GGF

Electromobility torenwerk10102334 replacement

IFE1300779 MODUL 68

AUTOROTOR51502 T5510/270 ° color RAL 7016 (new standard color replaces RAL 6011)

GEMU723 32D 214O4 AE2015

SCHRACKK003418.03 B2FRSV003

SCHRACKVFE0120 HV064011.B01

SCHRACKK003399.06 L1FRSV004 V01235.B02

NIEDERHAUSERRHU-200

ARPLASAL-S.QCS. QC.02

ARPLAS1965

ARPLAS3521

ATBENBF Y 63/4C-11

ALRE-ITJSF-1E 0-300M3/H 250VAC IP65 -40-85℃

SATLEAKCHECKER

UFMFS-EB-6N-833SLPM-R-X5A

AMEPAPSS/HT-K

APEX15LF081-38

SCHNEIDERXKB-A34229

P+FUB2000-30GM-E5-V15

ABBM2QA132M6B (Installation Method: B5 Vertical)

GEMU88270889 1436000Z1SA010101S01

JUMO60/60002157

ATB100L/2A-11

ADAMCZEWSKIAD-TV810-GS

PHOENIX2700642

E+L00210897-AG 2591

WOERNERKUI-A/10

PENTAIRS060526G050

NORGREN0AC006.500030

RINGSPAN3021.011.001.019,95

ElectronHRD 2T FU-95/3.0

KEB19F5A0H-350F

JERGENS25754

HUBA CONTROL525.9220031911

WOERNERKFA-A/O/O/165/135

JERGENS25754

PARKERP7P3L1A9A2A00

KAESER7.7601.0

EMGDES 56G 2-771-35W46-SWZ replacement

PANASONICCY-122AP

WALTHEREC-006-0-WR017-13-2-P020

REXROTHH-4WEH32HD63/OF6EG24N9EK4/B10D3

REXROTHH-4WEH 16HD72/OF6EG24N9EK4/B10D3

GEMU88296934 534 25D 890 51 1

INNOVATEG3-10-80-R10

PREVOSTKTM SM1

PIAB3116063

ELOBAU153V62SHD

ELOBAUK04G003

ELOBAU30428112BS

IFMII0104

ROEMHELD1897238VMH38

KSBSEALINIG KIT FOR ACTUATOR LAP-OF D250.004.5/30 F10

REGINDTTH4-420

GEMU88724181 R690 25D33 1291EDN

GEMUR69020D7871141EDN

VECTORVN1630A

VECTORCANOE PRO

GEMU88779703 620125D 8175434AD+1211000ZA002033001201+1211S01Z600600AT

GEMU88821944 620125D 8175424AF+1211000ZA002033001201+1211S01Z600600AT

FTA1.003.484

TRCEH582M-00135

TRCev582m -10591

AIRPOWERAPS-140/090-10-F10/F12-V27-H

GEMU417 25D91140AAN2 99061373

GEMU9554 40Z1420AN90 99082606

BELLMER KUFFERATH1000512950

MICHAEL RIEDEL1739021-02

MICHAEL RIEDELThe carbon brush matched with the variable resistor

FESTOXX160149510 MS12-LFR-AGG-D6-E-U-V-LD-AS quotation is valid until July 27, 2022

GEMU88706149 R690 32D7871291FDN replacement

DITTMERENGD09/073085

PANASONICPANCY122AP CY-122A-P (2M cable)

SCHMERSAL103045791 AZM300Z-ST-1P2P-DU

SCHMERSAL101218025 AZ/AZM300-B1

SCHMERSAL103044800 AZM300Z-I2-ST-1P2P-DU

MAYR8200311, up 5% on August 1st

BAUMERITD 70 A 4 Y 7 1024 H NI H2SK12 S 60 11059642

BONFIGLIOLIACU 401-18 FA BG2

BONFIGLIOLIBMD 102 7.2 3000 400 100 19 K 65 PTC SEN P1N CUS

BONFIGLIOLIDS179675203

SCHMERSALAZM300Z-I2-ST-1P2P-DU

NodDSP7001-0-0 replacement

NodHB-140M-2

BUHLERNT 63-K4-MS-M3/520

LOESIFDR 6/6 S3A HK

COLMEXAE-33/4 V1 0,2KW

EUCHNERCET3-AR-CRA-CH-50X-SG-110906

EUCHNERMGB-L2H-ARA-R-113149

DUNKERMOTORS88851 01652 +88632 01410

BEDIA600425，04.00075.0035

MICHELLEA2-TX+(-100/+20C)+EA2-TX-HD

KNFN86KNE

VAHLE0168044/00

COAX538877

COAX538877

SARTORIUSAvailable models PR6211/31D1; PR6211/51D1； PR6211/12D1； PR6211/22D1； PR6211/32D1 has information available

ALLEN-BRADLEY836T-T253J

BALANCE SYSTEMS9MISTG20TLN030

GESSMANNV64-03Z+03Z-A110

WOERNERKFA-A/G/260 replacement

DOSATROND3RE10V

SCHUNK0300510 PZN 64/1 AS

SALMSONN0S32/200B-5.5-2-14.2-ABB

ELFIN050F11

ELFIN050S031

BUSSMANN170M3819D

ALLEN-BRADLEY700-HPSXZ24 (pack of 10 pieces)

ALLEN-BRADLEY700-HN119

ALLEN-BRADLEY700-HN123

ALLEN-BRADLEY700-ADL1R

SPMDoes SPM 42000 require accessories? SPM 16598 is not included in the quotation

SPMSPM TRV-20

SPEEDLINE6-0056-113-07-1

HALDEREH 2276.052

HERRBRG-2000 DEB

PA INDUSTRIES15783

PA INDUSTRIES14287-05

PA INDUSTRIES14287-06

PA INDUSTRIES15492

PA INDUSTRIES14316-02

PA INDUSTRIES15926

ALLEN-BRADLEY9300-RADKIT (9300-RADM1 is the part number for the 9300-RADKITS modem, but cannot be ordered separately.)

ALLEN-BRADLEY440P-MSLB22B

ALLEN-BRADLEY1756-CNB

PARKERD31FHE02C1NB004

VECTORVN1630A CAN/LIN NETWORK INTERFACE

REVORD5012005000000

PARKER3309111349

AB1734-IB8S

Operational failures refer to faults that occur in electromagnetic flow meters after being debugged and operating normally for a period of time. Common operational failures are mainly caused by factors such as the adhesion layer on the inner wall of the flow sensor, lightning strikes, and changes in environmental conditions.

1. Adhesive layer on the inner wall of the sensor

Due to the fact that electromagnetic flow meters are often used to measure dirty fluids, after running for a period of time, they often accumulate adhesion layers on the inner wall of the sensor and cause malfunctions. These faults are often caused by the conductivity of the adhesion layer being too high or too low. If the attachment is an insulation layer, the electrode circuit will break and the instrument will not work properly; If the conductivity of the adhesion layer is significantly higher than that of the fluid, a short circuit will occur in the electrode circuit,

The instrument is also not functioning properly. Therefore, it is necessary to promptly remove the attached scale layer inside the measuring tube of the electromagnetic flowmeter.

1. Lightning strike

Lightning strikes can easily induce high voltage and surge current in the instrument circuit, causing damage to the instrument. It is mainly introduced through power lines or excitation coils or flow signal lines between sensors and converters, especially from the control room power lines, which account for the vast majority.

1. Changes in environmental conditions

During the debugging period, due to good environmental conditions (such as no interference source), the flowmeter works normally, but it is often easy to overlook installation conditions (such as poor grounding). In this case, once the environmental conditions change and new interference sources appear during operation (such as welding on pipelines near the flowmeter, installing large transformers nearby, etc.), it will interfere with the normal operation of the instrument, and the output signal of the flowmeter will fluctuate.

Common Faults

Typical fault diagnosis and handling

1. No traffic output. Check if there are any faults in the power supply and test if the power supply voltage is normal; Test the continuity of the fuse; Check if the sensor arrow is consistent with the fluid flow direction. If not, change the installation direction of the sensor; Check if the sensor is filled with fluid. If not, replace the pipeline or install it vertically.

2. The signal becomes smaller or suddenly drops. Test whether the insulation between the two electrodes is damaged or short circuited, and the normal resistance value between the two electrodes is between (70-100) Ω; The inner wall of the measuring tube may accumulate dirt, and the electrode should be cleaned and wiped to avoid scratching the inner lining. Measure whether the lining of the measuring tube is damaged, and replace it if damaged.

3. If the zero point is unstable, check whether the measuring tube is filled with the medium and whether there are bubbles in the medium. If there are bubbles, install an air purifier upstream. If it is installed horizontally, it can be changed to a vertical installation; Check if the instrument grounding is intact. If it is not good, a three-level grounding should be carried out (grounding resistance ≤ 100 Ω); The conductivity of the medium should not be less than 5 μ s/cm; Check if the medium has accumulated in the measuring tube, and be careful not to scratch the inner lining when removing it.

4. The flow indication value does not match the actual value. Check if the fluid in the sensor is filled in the tube and if there are any bubbles. If there are bubbles, install an air purifier upstream; Check if all grounding conditions are in good condition; Check if there is a valve upstream of the flowmeter. If so, move it downstream or fully open it; Check if the range setting of the converter is correct. If not, reset the correct range.

5. The displayed value fluctuates within a certain range. Check whether the environmental conditions have changed. If new interference sources or other magnetic sources or vibrations that affect the normal operation of the instrument appear, the interference should be promptly removed or the flowmeter should be moved; Check and test the signal cable, and use insulation tape to treat the end so that the wire, inner shielding layer, outer shielding layer, and shell do not come into contact with each other.

The fluid used to measure flow rate with an electromagnetic flowmeter must be conductive, so non-conductive substances such as gases, vapors, oils, and copper cannot be measured with an electromagnetic flowmeter.

operational failure

The common causes of faults that occur during operation after initial debugging and normal operation for a period of time include: adhesion layer on the inner wall of the flow sensor, lightning strikes, and changes in environmental conditions.

1. Inner wall adhesion layer

Due to the fact that electromagnetic flow meters have a much higher chance of measuring suspended solids or pollutants compared to other flow meters, the probability of failure caused by the adhesion layer on the inner wall is relatively high. If the conductivity of the adhesion layer is similar to that of the liquid, the instrument can still output signals normally, but only change the flow area, resulting in an implicit fault of measurement error; If there is a high conductivity adhesion layer, the electromotive force between the electrodes will be short circuited; If it is an insulating adhesive layer, the electrode surface will be insulated and the measurement circuit will be disconnected. Both of the latter two phenomena will cause the instrument to malfunction.

2. Thunder shock

Lightning strikes induce instantaneous high voltage and surge current in the power line, which can damage the instrument when it enters. There are three ways to introduce lightning damage instruments: power lines, flow signal lines between sensors and converters, and excitation lines. However, based on the analysis of damaged components caused by lightning faults, most of the induced high voltage and surge current that caused the fault were introduced from the power supply lines in the control room, and the other two pathways were relatively few. It was also learned from the scene of the lightning strike accident that not only did the electromagnetic flowmeter malfunction, but other instruments in the control room often experienced lightning strikes at the same time. Therefore, the user unit should recognize the importance of setting up lightning protection facilities for instrument power lines in the control room. The current team of design units has identified and explored solutions to this problem, such as Qilu Petrochemical Design Institute.

3. Changes in environmental conditions

The main reason is related to the fault environment during the debugging period as mentioned above, but the interference source did not appear during the debugging period and intervened during the operation period. For example, an electromagnetic flowmeter with poor grounding protection may operate normally during the debugging period due to the absence of a factory interference source. However, during the operation period, a new interference source (such as a pipeline near the measurement point or pipeline welding at a distance) may interfere with the normal operation of the instrument, resulting in significant fluctuations in the output signal.

Maintenance case

Maintenance of electromagnetic flowmeter

1. Sensor inspection

Testing equipment: one 500M Ω insulation resistance tester and one multimeter.

2. Converter inspection

If the electromagnetic flowmeter is determined to be a converter fault and there is no problem with the external cause after inspection, please contact the manufacturer. Generally, the solution is to replace the circuit board.

Practice of measuring low conductivity media with electromagnetic flowmeter

Electromagnetic flowmeter is used to measure the volumetric flow rate of conductive liquid media with a conductivity greater than 5 μ s/cm. The measurement principle of electromagnetic flowmeter is mainly based on Faraday's law of electromagnetic induction, which means that when the fluid passes through the measuring tube, it induces an electromotive force by cutting the magnetic field lines. The electromotive force is proportional to the magnetic flux density. The product of the inner diameter of the measuring tube and the average flow velocity is measured. The electromotive force (flow signal) is detected by the electrode and sent to the converter through the cable. However, when measuring weak conductivity media, the electromotive force is difficult to be induced. Through on-site practical operation methods, we have summarized the following points for reference:

Firstly, it is necessary to determine whether the measured medium has conductivity;

Secondly, the installation of electromagnetic flow meters should strictly follow the product manual;

Once again, when debugging the electromagnetic flowmeter, the parameter of empty tube alarm in the electromagnetic flowmeter converter can be turned off to smoothly detect the electromotive force.

The calculation method for determining the diameter of electromagnetic flowmeter:

Electromagnetic flowmeter is mainly used to measure the volumetric flow rate of conductive liquids in closed pipelines. The minimum flow velocity of the fluid specified by electromagnetic flowmeter is not less than 0.5m/s, normally between 2-4m/s, and the highest is not higher than 8m/s. Therefore, when choosing the diameter of electromagnetic flowmeter, we need to fully consider selecting the appropriate pipeline size while ensuring the measurement accuracy of electromagnetic flowmeter. So, how to determine the diameter of electromagnetic flowmeter? Let me briefly introduce how to determine the diameter of an electromagnetic flowmeter?

I assume that there is a 500m ³ pool of water that needs to be drained with a water pump within 4 hours. How can I determine what diameter of pipeline to use? The flow range of the flowmeter can be determined based on the parameters required above: 500m ³ divided by 4 hours equals 125m ³/h. The approximate range of pipeline diameter can be calculated through flow rate, which is: π r ² × flow rate (0.5~8m/s)=125m ³/h. By calculation, it is known that to pump out 125m ³/h of water, the diameter range is between 0.075m~0.2975m, i.e. DN80~DN300. Considering the accuracy requirements of electromagnetic flow meters, the optimal flow rate is 2~4m/s. By calculating the diameter range from 0.105m~0.149m, i.e. DN100~DN150, taking into account various factors such as investment, I can determine that DN100 is more suitable.

Installation steps for plug-in electromagnetic flowmeter

1. The plug-in electromagnetic flowmeter requires that the user's pipeline should be set horizontally, with at least 5DN in front of the sensor and at least 3DN of straight pipe section behind it. The flow control valve should be located 3DN downstream of the sensor. The pipeline should vibrate significantly, and the inner wall of the pipeline should have no obvious unevenness.

2. First, open a hole with a diameter of 60-62mm directly above the pipeline measurement point. The edges around the circular hole should be smooth, without burrs or gas cutting scars.

3. Unscrew the installation component from the sensor and reliably weld it to the above-mentioned opening. The requirement is to make the lower end of the installation component flush with the inner surface of the pipeline and ensure that there is no leakage

4. Loosen the three locking screws of the sensor and pull out the detection rod and detection head as a whole for later installation. (Note: Users are not allowed to open the connection between the detection head and the insertion rod)

5. Wrap hemp thread lead oil or PTFE tape around the upper thread of the installation component, and then tighten the ball valve and sealant locking mechanism on top.

6. Slowly insert the detection rod from above, tighten the locking nut slightly, press down on the insertion rod, measure L2 and record L2 dimensions, and the installation is complete.

Influencing factors and selection considerations

1、 The influence of various media on measurement

The influence of flow velocity distribution is known from fluid mechanics. When liquid flows in a pipeline, the flow velocity at each point on the cross-section of the pipeline is not equal. However, whether it is laminar or turbulent, after passing through a certain distance of straight pipe section, the flow velocity can become an axisymmetric distribution. The flow velocity is maximum at the center of the pipe axis and zero at the pipe wall, with an average flow velocity of V. As long as the flow velocity distribution is symmetrical with respect to the central axis of the measuring pipe, the magnitude of the induced electromotive force generated on the electrode is independent of the flow velocity distribution at each point, but only proportional to the average flow velocity of the measured liquid. Therefore, axisymmetric flow velocity distribution is one of the working conditions that a uniform magnetic field electromagnetic flowmeter must meet. If the velocity distribution is asymmetric relative to the central axis of the tube, although the total flow rate is the same, the induced electromotive force near the electrode is large, so the measured signal is larger than the actual flow rate value. On the contrary, the signal obtained by inducing a small electromotive force at a 90 ° angle to the electrode is smaller than the actual flow rate value, causing measurement errors. Therefore, in order to make the flow velocity distribution axis symmetrical, it is necessary to add a straight pipe section in front of the flowmeter.

⑵ The influence of magnetic field edge effect on measurement. If it is assumed that the magnetic field is always uniform along the flow direction of the fluid, in fact, this means that the magnetic field along the pipe axis is infinitely long. However, the actual magnetic field of the flowmeter is finite in length, so the influence of edge effect generated by finite length magnetic field on measurement must be considered. Assuming the pipe wall is insulated, the magnetic field near the electrode is roughly uniform, and the two ends gradually weaken, forming uneven edges, and finally dropping to zero. In this way, the electric field E inside the liquid is also uneven, which will generate eddy currents. The secondary magnetic flux generated by eddy currents in turn changes the working magnetic flux at the edge of the magnetic field, further disrupting the uniformity of the magnetic field. At this point, the induced electromotive force measured on the electrode is different in magnitude from the induced electromotive force under an infinitely long magnetic field, resulting in an error. If the pipe wall is conductive, the magnetic field edge effect will be more pronounced due to the short-circuit effect of the conductive pipe wall. As the conductivity and wall thickness of the pipe wall change, this effect will also become more pronounced, resulting in an increase in the loss of induced electromotive force on the electrode. For electromagnetic flow meters, it is essential to measure the insulation of the pipe wall, so the pipe wall is usually coated with an insulation layer. If the tested medium contains magnetic substances, the magnetic field edge effect becomes more complex. Due to the presence of magnetic materials, the magnetic field undergoes severe distortion, resulting in measurement nonlinearity. So for liquids containing liquid metal, DC excitation is generally used to reduce magnetic field edge effects.

⑶ The influence of the conductivity of the measured medium. When the input impedance of the electromagnetic flowmeter converter has been increased to measure conductive liquids, it generally does not cause errors due to slight changes in the conductivity of the medium. However, for a certain input impedance of the converter, there is a lower limit value for the conductivity of the measured medium, which cannot be lower than this lower limit value. It is also not allowed for the conductivity of the measured medium to be too high. For example, when the conductivity exceeds about 10-1S/cm, the flow signal will be reduced and the indicated value will be changed, that is, the indicated flow value will be smaller than the actual flow value. When the conductivity of the measured medium is high, the resistance of the external circuit is small. At this time, regardless of how high the input impedance of the converter is, the parallel connection result will depend on this part of the liquid external circuit, thereby reducing the transmission accuracy between the transmitter and the converter. So, for an electromagnetic flowmeter, the measurement is not affected by the conductivity of the medium within a certain range, and the conductivity of the measured medium cannot be too high or too low. If the conductivity of the medium is high, a large eddy current will be generated in the magnetic field edge region, causing secondary magnetic flux and weakening and strengthening the magnetic fields on both sides of the working magnetic field edge region. Therefore, for media with high conductivity, AC excitation should not be used, and DC excitation should be used instead. With the development of electronic technology, the increase in input impedance of converters will inevitably lower the lower limit of the measured dielectric conductivity.

3、 The selection of electromagnetic flowmeter electrode materials for flow sensors. Improper selection of electrode materials and the measured medium may affect normal measurement due to chemical reactions or polarization phenomena. The electrode material should be selected based on the corrosiveness of the measured medium. Select the lining material for the electromagnetic flowmeter based on the corrosiveness, wear resistance, and temperature of the measured medium. Try to choose electromagnetic flow meters with lightning protection function.

4、 Installation of flow sensor

1. Requirements for installation site. 

1) When measuring mixed phase fluids, choose a location that will not cause phase separation. When measuring two-component liquids, avoid installing them downstream where mixing is not yet uniform. When measuring chemical reaction pipelines, they should be installed in the fully completed reaction section. 

2) Try to avoid negative pressure inside the measuring tube as much as possible. 

3) Choose a location with low vibration, especially for integrated instruments.

4) Avoid large motors, transformers, etc. nearby to prevent electromagnetic interference. 

5) A place that is easy to implement separate grounding for sensors. 

6) Try to avoid high concentrations of corrosive gases in the surrounding environment as much as possible. 

7) The ambient temperature should be within the range of -25-60 ℃, the relative humidity should be within the range of 10% -90%, and direct sunlight should be avoided as much as possible. 

8) The liquid should have the required conductivity for measurement, and the conductivity distribution should be generally uniform. Therefore, the installation of flow sensors should avoid areas that are prone to uneven conductivity, such as adding liquid near their upstream, and the liquid addition point should preferably be located downstream of the sensor.

2. The length requirement for the straight pipe section is relatively low for electromagnetic flow meters. For 90o bend pipes, T-shaped tees, concentric reducers, and fully opened gate valves, the straight pipe section that is not more than 5 times the diameter length of the sensor inlet connection surface usually only needs to be away from the electrode centerline. Valves with different opening degrees require 1OD, and downstream straight pipe sections are 3D. When measuring mixed liquids of different media, the distance between the mixing point and the flow meter should be at least greater than 30D

According to the different types of external magnetic fields, there are mainly two types of electromagnetic flow meters: DC type and induction type. The external constant lower magnetic field B of the DC electromagnetic flowmeter (Figure 2) is perpendicular to the tube axis, and two electrodes are installed at positions C and D to measure the electromotive force U induced by the fluid crossing the magnetic field. The flow rate Q can be calculated using the following formula:

‍

Magnetic circuit system: Its function is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented using magnets, which has the advantages of a relatively simple structure and less interference from AC magnetic fields. However, it can easily polarize the electrolyte liquid inside the measuring tube, causing the positive electrode to be surrounded by negative ions and the negative electrode to be surrounded by positive ions, resulting in electrode polarization and an increase in internal resistance between the two electrodes, which seriously affects the normal operation of the instrument. When the diameter of the pipeline is large, the magnet is also large, bulky, and uneconomical. Therefore, electromagnetic flow meters generally use alternating magnetic fields and are excited by a 50HZ power supply. Measurement catheter: Its function is to allow the measured conductive liquid to pass through. In order to divert or short-circuit the magnetic flux when the magnetic field lines pass through the measuring conduit, the measuring conduit must be made of non-magnetic, low conductivity, low thermal conductivity, and materials with certain mechanical strength, such as non-magnetic stainless steel, fiberglass, high-strength plastic, aluminum, etc. Electrode: Its function is to generate an induced potential signal proportional to the measured value. The electrode is generally made of non-magnetic stainless steel and is required to be flush with the lining so that fluid can pass through without obstruction. Its installation position should be in the vertical direction of the pipeline to prevent sediment from accumulating on it and affecting measurement accuracy. Shell: Made of ferromagnetic material, it is the outer shell of the distribution system excitation coil and isolates the interference of external magnetic fields. Lining: There is a complete layer of electrical insulation lining on the inner side of the measuring conduit and the flange sealing surface. It directly contacts the measured liquid and its function is to increase the corrosion resistance of the measuring conduit, preventing the induced potential from being short circuited by the metal measuring conduit wall. The lining materials are mostly corrosion-resistant, high-temperature resistant, wear-resistant polytetrafluoroethylene plastics, ceramics, etc. Converter: The induced potential signal generated by liquid flow is very weak and greatly affected by various interference factors. The function of the converter is to amplify and convert the induced potential signal into a unified standard signal and suppress the main interference signal. Its task is to amplify and convert the induced potential signal Ex detected by the electrode into a unified standard DC signal. Feature 1: The measurement is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity; 2. Measure the flow components inside the tube, with no pressure loss and low requirements for straight pipe sections. Adaptability to slurry measurement; 3. Reasonably selecting sensor lining and electrode materials, which have good corrosion resistance and wear resistance; 4. The converter adopts a novel excitation method, with low power consumption, stable zero point, and high accuracy. The flow range can reach 150:1; 5. The converter can be integrated or separated from the sensor; 6. The converter adopts a 16 bit high-performance microprocessor, 2x16 LCD display, convenient parameter setting, and reliable programming; 7. The flowmeter is a bidirectional measurement system equipped with three integrators: forward total, reverse total, and differential total; It can display positive and negative flow rates and has multiple outputs: current, pulse, digital communication HART； 8. The converter adopts surface mount technology (SMT) and has self checking and self diagnostic functions; 9. The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity. The sensor's induced voltage signal is linearly related to the average flow rate, resulting in high measurement accuracy. 10. There is no obstruction in the measuring pipeline, so there is no additional pressure loss; There are no movable parts inside the measuring pipeline, so the sensor has an extremely long lifespan. 11. Due to the fact that the induced voltage signal is formed in the entire space filled with a magnetic field and is the average value on the surface of the pipeline, the sensor requires a shorter straight pipe section, with a length of 5 times the diameter of the pipeline. 12. The converter adopts the latest international microcontroller (MCU) and surface mount technology (SMT), with reliable performance, high accuracy, low power consumption, stable zero point, and convenient parameter setting. Click on the Chinese display LCD to show cumulative flow, instantaneous flow, flow rate, flow percentage, etc. 13. A bidirectional measurement system that can measure both forward and reverse flow rates. Using special production processes and high-quality materials to ensure the stability of product performance over a long period of time. According to the different types of external magnetic fields, there are mainly two types of electromagnetic flow meters: DC type and induction type. The external constant lower magnetic field B of the DC electromagnetic flowmeter (Figure 2) is perpendicular to the tube axis, and two electrodes are installed at positions C and D to measure the electromotive force U induced by the fluid crossing the magnetic field. The flow rate Q can be calculated using the following equation: Magnetic circuit system: Its function is to generate a uniform DC or AC magnetic field. The DC magnetic circuit is implemented using magnets, which has the advantages of a relatively simple structure and less interference from AC magnetic fields. However, it can easily polarize the electrolyte liquid inside the measuring tube, causing the positive electrode to be surrounded by negative ions and the negative electrode to be surrounded by positive ions, resulting in electrode polarization and an increase in internal resistance between the two electrodes, which seriously affects the normal operation of the instrument. When the diameter of the pipeline is large, the magnet is also large, bulky, and uneconomical. Therefore, electromagnetic flow meters generally use alternating magnetic fields and are excited by a 50HZ power supply. Measurement catheter: Its function is to allow the measured conductive liquid to pass through. In order to divert or short-circuit the magnetic flux when the magnetic field lines pass through the measuring conduit, the measuring conduit must be made of non-magnetic, low conductivity, low thermal conductivity, and materials with certain mechanical strength, such as non-magnetic stainless steel, fiberglass, high-strength plastic, aluminum, etc. Electrode: Its function is to generate an induced potential signal proportional to the measured value. The electrode is generally made of non-magnetic stainless steel and is required to be flush with the lining so that fluid can pass through without obstruction. Its installation position should be in the vertical direction of the pipeline to prevent sediment from accumulating on it and affecting measurement accuracy. Shell: Made of ferromagnetic material, it is the outer shell of the distribution system excitation coil and isolates the interference of external magnetic fields. Lining: There is a complete layer of electrical insulation lining on the inner side of the measuring conduit and the flange sealing surface. It directly contacts the measured liquid and its function is to increase the corrosion resistance of the measuring conduit, preventing the induced potential from being short circuited by the metal measuring conduit wall. The lining materials are mostly corrosion-resistant, high-temperature resistant, wear-resistant polytetrafluoroethylene plastics, ceramics, etc. Converter: The induced potential signal generated by liquid flow is very weak and greatly affected by various interference factors. The function of the converter is to amplify and convert the induced potential signal into a unified standard signal and suppress the main interference signal. Its task is to amplify and convert the induced potential signal Ex detected by the electrode into a unified standard DC signal. Feature 1: The measurement is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity; 2. Measure the flow components inside the tube, with no pressure loss and low requirements for straight pipe sections. Adaptability to slurry measurement; 3. Reasonably selecting sensor lining and electrode materials, which have good corrosion resistance and wear resistance; 4. The converter adopts a novel excitation method, with low power consumption, stable zero point, and high accuracy. The flow range can reach 150:1; 5. The converter can be integrated or separated from the sensor; 6. The converter adopts a 16 bit high-performance microprocessor, 2x16 LCD display, convenient parameter setting, and reliable programming; 7. The flowmeter is a bidirectional measurement system equipped with three integrators: forward total, reverse total, and differential total; It can display positive and negative flow rates and has multiple outputs: current, pulse, digital communication HART； 8. The converter adopts surface mount technology (SMT) and has self checking and self diagnostic functions; 9. The measurement accuracy is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity. The sensor's induced voltage signal is linearly related to the average flow rate, resulting in high measurement accuracy. 10. There is no obstruction in the measuring pipeline, so there is no additional pressure loss; There are no movable parts inside the measuring pipeline, so the sensor has an extremely long lifespan. 11. Due to the fact that the induced voltage signal is formed in the entire space filled with a magnetic field and is the average value on the surface of the pipeline, the sensor requires a shorter straight pipe section, with a length of 5 times the diameter of the pipeline. 12. The converter adopts the latest international microcontroller (MCU) and surface mount technology (SMT), with reliable performance, high accuracy, low power consumption, stable zero point, and convenient parameter setting. Click on the Chinese display LCD to show cumulative flow, instantaneous flow, flow rate, flow percentage, etc. 13. A bidirectional measurement system that can measure both forward and reverse flow rates. Using special production processes and high-quality materials to ensure the stability of product performance over a long period of time. Classification 2) Determine the electrode material based on the learned properties of the dielectric; The company generally provides four types of electrodes: stainless steel, Hastelloy, titanium, and tantalum. The selection of which electrode should be based on the properties of the medium and relevant information manuals. (2) Determine whether to use rubber or PTFE lining based on the temperature of the medium learned (determined by the marketer). Note that the temperature resistance of rubber should not exceed 80C; PTFE should withstand 150C, and can withstand 180C instantly; urban sewage can generally use rubber lining and stainless steel electrodes. (3) Select the flange specification of the body according to the learned medium pressure (determined by the marketer). Note that the electromagnetic flange specification is usually ≤ 1.6Mpa when the diameter is from DN10-250; When the diameter ranges from DN250 to 1000, the rated pressure of the flange is ≤ 1.0Mpa; When the actual pressure of the medium is higher than the corresponding range of pipe diameter and pressure mentioned above, it is a special order, but the maximum pressure should not exceed 6.4Mpa. (4) Note the conductivity of the medium: (1) The conductivity of the electromagnetic flowmeter should not be lower than 5uS/cm. (2) The conductivity of tap water is about tens to hundreds of uS/cm. Generally, boiler soft water (deionized water) is conductive, while pure water (highly distilled water) is non-conductive. (3) The conductivity of gases, oils, and most organic liquids is much lower than 5uS/cm and non-conductive. 3. Understand user requirements: (1) Understand whether it is a combination type local display or a split type remote transmission display (provided by the user) Note: When it is a split type remote transmission display, please understand the maximum distance, and the maximum separation distance is 100 meters. (2) Understand whether other additional functions (provided by the user) are needed. Note: 1. The electromagnetic flowmeter itself has upper and lower limit flow alarm, frequency and current output functions, and no special ordering is required. 2. The sealing protection level of the electromagnetic flowmeter housing is IP65 and IP68, which are special orders when choosing the submersible IP68 type. 3. When the electromagnetic flowmeter needs to be connected to a computer, an RS-485 communication port needs to be added, which is a special order. 4. Selection: After the above steps, the model and specifications of the electromagnetic flowmeter can be finally determined. The electromagnetic flowmeter has two operating states: automatic measurement state and parameter setting state. When the instrument is powered on, it automatically enters the measurement state. In automatic measurement mode, the electromagnetic flowmeter automatically completes various measurement functions and displays corresponding measurement data. In the parameter setting state, the user uses four panel keys to complete the instrument parameter setting. 1. Key Function: Automatic Measurement State. Key Function: Loop Selection of Screen Down Display Content. Up Key Loop Selection of Screen Up Display Content. Composite Key+Confirm Key. Enter Parameter Setting State. Confirm Key. Return to Automatic Measurement State. In the measurement state, adjust the contrast of the LCD display: For the small LCD, press the "Composite Key+Up Key" or "Composite Key+Down Key" for a few seconds; The large LCD is achieved by adjusting the potentiometer on the back of the large LCD. In the parameter setting state, the key function is to subtract 1 from the number at the cursor position, add 1 to the number at the cursor position, use the composite key, move the cursor left with the composite key, and move the cursor right with the up key to enter/exit the submenu. In any state, press the confirmation key continuously for two seconds to return to the automatic measurement state. Note: 1. When using the "composite key", press the composite key first and then hold down the "up key" or "down key" at the same time. 2. In the parameter setting state, if there is no key operation within 3 minutes, the instrument will automatically return to the measurement state. 3. The flow direction selection for zero point correction of flow can be switched by moving the cursor to the leftmost "+" or "-" and using the "up" or "down" keys to make it opposite to the actual flow direction. 4. To select the unit of flow, you can move the cursor to the original displayed flow unit in the "Flow Range Setting" menu, and then use the "Up" or "Down" keys to switch to meet your needs. 2. To set or modify the parameters of an electromagnetic flowmeter using the parameter setting function key, the flowmeter must enter the parameter setting state from the measurement state. In the measurement state, press the "composite key+confirm key" to display the state transition password (0000). According to the confidentiality level, modify the password provided by the manufacturer accordingly. After pressing the "composite key+confirm key" again, it will enter the desired parameter setting state. Installation of Intelligent Electromagnetic Flow Meter Sensor on Process Pipeline 1. The measuring tube of the intelligent electromagnetic flow meter must be filled with medium at any time and cannot work normally without filling or emptying the tube. When the medium is not fully filled in the pipe, the method of raising the height of the outlet pipe at the back of the flowmeter can be used to fill the pipe with the medium, avoiding the incomplete pipe and gas from adhering to the electrode. 2. Vacuum inside the pipeline can damage the lining of the flowmeter, so special attention should be paid. 3. The positive direction of flow should be consistent with the positive direction indicated by the arrow on the flowmeter. 4. The intelligent electromagnetic flowmeter can be installed on straight pipelines, as well as on horizontal or inclined pipelines, but it requires that the center line of the two electrodes be in a horizontal state. 5. For liquid and solid two-phase fluids, it is best to use vertical installation to allow the measured medium to flow from top to bottom, which can evenly wear the lining of the flowmeter and extend its service life. 6. Ensure that there is sufficient space near the pipeline flange for the installation and maintenance of the flowmeter. If there is vibration in the measuring pipeline, there should be fixed supports on both sides of the flowmeter. 8. If the measuring medium is a heavily polluted liquid, a flowmeter body can be installed in the bypass pipeline without interrupting the process operation, which can be emptied and cleared. 9. When installing a flow meter with PTFE lining, the bolts connecting the flange should be tightened evenly, otherwise it is easy to crush the PTFE lining. It is best to use a torque wrench. The electromagnetic flowmeter is simply composed of a flow sensor and transmitter. The installation requirement of electromagnetic flowmeter is to be installed at the point of the pipeline or the vertical section of the pipeline, but it must be installed when the pipeline is full. The requirement for the straight pipe section is the first 5D and then 3D, so as to ensure the use of electromagnetic flowmeter and the accuracy requirements. The measurement principle of electromagnetic flowmeter does not depend on the characteristics of flow rate. If there is a certain amount of turbulence and vortex generated in the non measurement area of the pipeline (such as bends, tangential flow restrictions, or partially open shut-off valves upstream), it is irrelevant to the measurement. If there is a steady-state eddy current in the measurement area, it will affect the stability and accuracy of the measurement. In this case, some measures should be taken to stabilize the flow velocity distribution: 1 Increase the length of the front and rear straight pipe sections by 2 Adopting a traffic stabilizer 3 Reduce the cross-section of measurement points. 1. Requirements for external environment 1.1. Flow meters should be avoided from being installed in places with large temperature changes or high temperature radiation from equipment. If installation is necessary, insulation and ventilation measures must be taken. 1.2. It is best to install the flowmeter indoors. If it must be installed outdoors, it should be protected from rainwater, waterlogging, and direct sunlight. Moisture and sun protection measures should be taken. 1.3. Flow meters should be avoided from being installed in environments containing corrosive gases, and ventilation measures must be taken when installation is necessary. 1.4. For the convenience of installation, maintenance, and upkeep, there should be ample installation space around the flowmeter. 1.5. The installation site of the flowmeter should avoid magnetic fields and strong vibration sources. If the pipeline vibration is large, there should be fixed pipe supports on both sides of the flowmeter. 1. 2. 2.1. Requirements for straight section of pipeline electromagnetic flowmeter In order to improve the influence of eddy current and flow field distortion, there are certain requirements for the length of the straight pipe section before and after the installation of the flowmeter, otherwise it will affect the measurement accuracy (rectifier can also be installed, try to avoid installation near the regulating valve and half open valve). 2.2. Requirements for Process Pipes Flow meters have certain requirements for the upstream and downstream process pipes of the installation point, otherwise it will affect the measurement accuracy. a. The inner diameter of the upstream and downstream process pipes should be the same as that of the sensor, and should meet the following requirements: 0.98DN ≤ D ≤ 1.05DN (where DN is the inner diameter of the sensor and D is the inner diameter of the process pipe). b. The process pipe and the sensor must be concentric, and the coaxial deviation should not exceed 0.05DN2.3. Requirements for bypass pipes. In order to facilitate the maintenance of flow meters, it is best to install bypass pipes for flow meters. In addition, for heavily polluted fluids and flow meters that need to be cleaned but cannot be stopped, bypass pipes must be installed. a. Convenient maintenance of flow meters. b. Heavy polluted fluids must be installed. c. The fluid cannot be stopped and the flow meter needs to be cleaned. 3. Installation requirements for plug-in electromagnetic flow meters. 3.1. Requirements for straight pipe sections: inlet should be ≥ 10 × DN; outlet should be ≥ 5 × DN3.2 The docking point requirements are to ensure the reliable operation of the instrument, improve measurement accuracy, and avoid interference from external parasitic potentials. The sensor should have good grounding with a grounding resistance of less than 10. (If the metal pipeline is well grounded, there is no need to set up a dedicated grounding device.) 3.3 The installation position requirements are as shown in the figure. The electromagnetic flowmeter should be inserted according to the on-site pipeline situation. For flow meters without ball valves, they should be installed on pipelines without pressure (i.e. flow meters without ball valves can be selected for installation without pressure). The diameter of the hole on the pipeline should be 50, and the connecting welded pipe should be welded to the opening of the pipeline; For situations that require continuous loading and unloading or do not allow medium overflow, ball valves must be installed, that is, plug-in electromagnetic flow meters with ball valve structures should be selected; Drill a hole with a diameter of 50 on the pipeline and prepare to weld the connecting welded pipe onto the opening of the pipeline. The recommended measurement range for plug-in electromagnetic flowmeter selection is 0.5m/s to 10m/s, with continuous adjustable maximum range of 0.2m/s to 15m/s. The continuous adjustable signal output switch can be set to pulse output (up to 1000HZ), high/low flow alarm, air traffic alarm, flow direction indication, fault alarm, current output, 4-20mA output. The configuration can be done on-site through three manual keys, remote control, and on-site configuration. The EEPROM memory will not disappear and does not require battery storage. This indicates that electromagnetic flowmeters are widely used in various fields such as sewage, fluorine chemical industry, production water, tap water industry, medicine, steel, etc. Due to its principle, it can only measure conductive liquids. Although it is much better than other types of flow meters in terms of reliability and stability, customers still encounter some problems in actual use. Below, I will explain in detail the selection and installation of electromagnetic flow meters: First, like other flow meters, although the measurement range of electromagnetic flow meters is 30:1, which is higher than vortex flow meters and differential pressure flow meters, it is also limited. Many customers often compare it with water meters when ordering a meter, thinking that it can measure very low flow rates. Generally, it can only measure 0.1m/s. It is difficult for electromagnetic flow meters to measure flow rates lower than this. So in the initial stage of ordering, it is necessary to clarify the flow range. When placing an order, it is not advisable to order according to the original pipe diameter. It is better to determine the instrument diameter based on your actual flow rate. 2、 Like other flow meters, electromagnetic flow meters also have requirements for straight pipelines before and after installation, although the requirements are lower than other types of flow meters. However, the most crucial point is to meet the requirement of full pipe and then full pipe. In the case of insufficient pipeline, it is easy to cause the flow meter to jump: Thirdly, like other flow meters, electromagnetic flow meters also have protection levels. Generally, the protection level of integrated flow meters is IP65, and the protection level of split type flow meters is IP68 (for sensors). If customers have requirements for the installation environment of the instrument, and the installation location is in underground manholes or other damp places, it is recommended that customers choose split type flow meters. To avoid selecting the wrong one and causing damage to the instrument. 4、 Electromagnetic flow meters can measure corrosive liquids, but in the initial stage of ordering, customers need to provide the correct properties of other measuring media to avoid errors in electrode selection during selection, which may result in the sensor being scrapped during later use, causing inconvenience and economic losses to customers. 5、 Although electromagnetic flow meters have good reliability and are generally not damaged, due to their principle, the sensor electrode surface is always in contact with the liquid, and over time, the electrode surface is more susceptible to contamination. Therefore, in general, for electromagnetic flowmeters, if customers have the conditions to disassemble them, it is recommended to remove and clean the electrodes once every one to one and a half years to ensure the measurement accuracy of the entire flowmeter. Any instrument requires maintenance, and electromagnetic flow meters are no exception. 6、 When the main pipeline is a vertical pipeline, it is generally required that the water flow should be from bottom to top, and should not be from top to bottom as much as possible. The latter can easily cause significant fluctuations in traffic. In addition to filling the pipes, this is also very important for installation, followed by the distance between the front and rear straight pipes. Choose a place that is easy to maintain and has convenient activities. The flowmeter should be installed at the rear end of the water pump and must not be installed on the suction side; The valve should be installed on the downstream side of the flow. The electromagnetic flowmeter is a flowmeter that measures flow based on Faraday's law of electromagnetic induction. The advantages of electromagnetic flowmeter are minimal pressure loss and a wide range of measurable flow rates. The ratio of maximum flow rate to minimum flow rate is generally above 20:1, suitable for a wide range of industrial pipe diameters, up to 3m. The output signal is linear with the measured flow rate, with high accuracy. It can measure the fluid flow rate of acid, alkali, salt solutions, water, sewage, corrosive liquids, as well as mud, slurry, pulp, etc. with conductivity ≥ 5 μ s/cm. But it cannot measure the flow of gas, steam, and purified water. When a conductor cuts magnetic field lines in a magnetic field, an induced potential is generated in the conductor, and the magnitude of the induced potential is proportional to the effective length of the conductor in the magnetic field and the speed at which the conductor moves perpendicular to the direction of the magnetic field. Similarly, when a conductive fluid flows vertically in a magnetic field and cuts magnetic induction lines, it will also generate induced potentials on the electrodes on both sides of the pipeline. The direction of the induced potential is determined by the right-hand rule, and the magnitude of the induced potential is determined by the following equation: Ex=BDv ------------------------ Equation (1), where Ex - induced potential, V; B - magnetic induction intensity, TD - inner diameter of the pipeline, mv - average flow velocity of the liquid, m/s. However, the volumetric flow rate qv is equal to the product of the fluid flow velocity v and the pipeline cross-sectional area (π D ²)/4. Substituting Equation (1) into this equation, Qv=(π D/4B) * Ex -------------- Equation (2) shows that when the pipeline diameter D is fixed and the magnetic induction intensity B remains constant, the measured volumetric flow rate is linearly related to the induced potential. If an electrode is inserted on each side of the pipeline, an induced potential Ex can be introduced, and the magnitude of this potential can be measured to obtain the volumetric flow rate. According to Faraday's principle of electromagnetic induction, a pair of detection electrodes are installed on the tube wall perpendicular to the axis of the measuring tube and the magnetic field lines. When the conductive liquid moves along the axis of the measuring tube, it cuts the magnetic field lines and generates an induced potential. This induced potential is detected by the two detection electrodes, and its value is proportional to the flow rate. Its value is E=B · V · D · K, where E - induced potential; K - coefficient related to magnetic field distribution and axial length; B - Magnetic induction intensity; V - average flow velocity of conductive liquid; D - electrode spacing; The sensor (measuring the inner diameter of the tube) uses the induced potential E as the flow signal, which is transmitted to the converter. After signal processing such as amplification, transformation and filtering, the instantaneous flow and cumulative flow are displayed on a backlit dot matrix LCD. The converter has 4-20mA output, alarm output and frequency output, and is equipped with communication interfaces such as RS-485, and supports HART and MODBUS protocols. Note: The parameters of different electromagnetic flow meters may vary slightly. Please be sure to refer to the instruction manual when using them. According to Faraday's law of electromagnetic induction, in a uniform magnetic field with a magnetic induction intensity of B, a non-magnetic pipeline with an inner diameter of D is placed perpendicular to the direction of the magnetic field. When a conductive liquid flows in the pipeline at a flow velocity v, the conductive fluid cuts the magnetic field lines If a pair of electrodes are installed at both ends perpendicular to the diameter of the magnetic field on the pipeline section, it can be proven that as long as the flow velocity distribution inside the pipeline is axisymmetric, an induced electromotive force is generated between the two electrodes: e=KBDv (3-36), where v is the average flow velocity on the pipeline section and k is the instrument constant. From this, the volumetric flow rate of the pipeline can be obtained as follows: qv=π eD/4KB (3-37). As can be seen from the above equation, the volumetric flow rate qv is linearly related to the induced electromotive force e and the inner diameter D of the measuring tube, inversely proportional to the magnetic induction intensity B of the magnetic field, and independent of other physical parameters. This is the measurement principle of electromagnetic flowmeter. It should be noted that in order for equation (3-37) to strictly hold, the measurement conditions of the electromagnetic flowmeter must satisfy the following assumptions: ① The magnetic field is a uniformly distributed constant magnetic field; ② The axisymmetric distribution of flow velocity of the measured fluid; ③ The tested liquid is non-magnetic; ④ The conductivity of the tested liquid is uniform and isotropic. The accuracy level and maximum allowable error of the flow meter within the specified flow range should comply with the provisions of Table 1. Flow meter error refers to the relative indication error. Accuracy level and maximum allowable error Accuracy level 0.2 (0.25) (0.3) 0.5 Maximum allowable error ± 0.2% (± 0.25%) (± 0.3%) ± 0.5% Accuracy level 1.01.52.5/Maximum allowable error ± 1.0% ± 1.5% ± 2.5 Error representation method; For flow meters that use a combination of relative indication error and reference error to represent errors, a unified method should also be used to represent their errors during a single calibration. The repeatability of a repetitive flow meter shall not exceed one-third of the maximum allowable absolute error specified for the corresponding accuracy level. The electromagnetic flowmeter has a large measurement range, usually from 20:1 to 50:1, with a wide optional flow range; The aperture range of electromagnetic flow meters is wider than other types of flow meters, ranging from a few millimeters to 3 meters; It can measure both positive and negative flow rates, as well as pulsating flow rates, as long as the pulsating frequency is much lower than the excitation frequency; The instrument output is essentially linear; Easy to choose material varieties for fluid contact parts, and can be applied to corrosive fluids and other advantages. Due to the fact that electromagnetic flow meters have a much higher chance of measuring suspended solids or pollutants compared to other flow meters, the probability of failure caused by the adhesion layer on the inner wall is relatively high. If the conductivity of the adhesion layer is similar to that of the liquid, the instrument can still output signals normally, but only change the flow area, resulting in an implicit fault of measurement error; If there is a high conductivity adhesion layer, the electromotive force between the electrodes will be short circuited; If it is an insulating adhesive layer, the electrode surface will be insulated and the measurement circuit will be disconnected. Both of the latter two phenomena will cause the instrument to malfunction. [1] The main product of the intelligent electromagnetic flowmeter adopts a backlit wide temperature dot matrix LCD display, all displays are in Chinese, with multiple and practical functions, especially convenient for users to operate, reducing unnecessary trouble and errors. Fast delivery, low cost, and easy maintenance. How does an electromagnetic flowmeter resist interference? When measuring large interference signals such as pulp/slurry, the use of 8707 high signal flow tube can improve signal strength. The intelligent electromagnetic flowmeter AFLD is designed based on the principle of full intelligence and has significant differences in measurement accuracy, function, reliability, and service life compared to old-fashioned or fake intelligent electromagnetic flowmeters produced by some domestic enterprises. The service life of electromagnetic flow meters should be over 10-20 years, so we fully consider this when designing. We are very careful in every detail from sensors to converters, from design, material selection, process, production, testing, etc. We pay great attention to every link and design customized production lines for specialized and electromagnetic flow meters in China to ensure the long-term quality of our products. The plug-in electromagnetic flowmeter is composed of a plug-in electromagnetic flow sensor (referred to as the sensor) and an electromagnetic flow converter (referred to as the converter). It is an instrument used to measure the volumetric flow rate of various conductive liquids inside pipelines. Insertion type electromagnetic flowmeter is used to measure the flow rate of conductive fluids in sectors such as tap water, steel, petroleum, chemical, power, industry, and water conservancy. It can also measure corrosive conductive liquids such as acids, alkalis, and salts. Attention: 1. Accuracy level and function: Select the instrument accuracy level based on measurement requirements and usage scenarios to achieve cost-effectiveness. For example, in situations such as trade settlement, product handover, and energy measurement, higher accuracy levels such as 1.0, 0.5, or higher should be selected; For process control applications, choose different accuracy levels according to control requirements; In some cases where only the process flow rate needs to be detected without precise control and measurement, a slightly lower accuracy level, such as 1.5, 2.5, or even 4.0, can be selected. In this case, a low-cost plug-in electromagnetic flowmeter can be used. 2. When measuring medium flow rate, instrument range, and caliber, the full flow rate of an electromagnetic flowmeter can be selected within the range of 0.5-12m/s for measuring medium flow rate, which is relatively wide. The selection of instrument specifications (caliber) may not necessarily be the same as the process pipeline, and should be determined based on whether the measured flow range is within the flow rate range. That is, when the pipeline flow rate is too low to meet the requirements of the flow instrument or the measurement accuracy cannot be guaranteed at this flow rate, the instrument port diameter needs to be reduced to increase the flow rate inside the pipeline and obtain satisfactory measurement results. 3. Try to avoid ferromagnetic objects and equipment with strong electromagnetic fields as much as possible to prevent the magnetic field from affecting the working magnetic field and flow signal of the sensor. 4. It should be installed in a dry and ventilated place as much as possible, avoiding direct sunlight and rain. The ambient temperature should be between -20 and+60 ℃, and the relative humidity should be less than 85%. 5. There should be ample space around the flowmeter for easy detection and maintenance. Daily maintenance broadcast editors only need to conduct periodic visual inspections of the instrument, check the surrounding environment of the instrument, remove dust and dirt, ensure that there is no water or other substances, check whether the wiring is good, and check whether there are newly installed strong electromagnetic field devices or newly installed wires crossing the instrument near the instrument. If the measuring medium is prone to contaminating the electrode or settling or scaling inside the measuring tube wall, regular cleaning and cleaning should be carried out. After the flowmeter is put into operation or has been in normal operation for a period of time, if it is found that the instrument is not working properly, the external condition of the flowmeter should be checked first, such as whether the power supply is good, whether the pipeline is leaking or in a non full state, whether there are bubbles in the pipeline, whether the signal cable is damaged, and whether the output signal of the converter (i.e. the input circuit of the rear instrument) is open circuit. Remember to blindly disassemble and repair the flowmeter. Sensor inspection and testing equipment: one 500M Ω insulation resistance tester and one multimeter. Test steps: (1) With the pipeline filled with medium, use a multimeter to measure the resistance between terminals A, B, and C. The resistance between A-C and B-C should be equal. If the difference is more than 1 times, it may be due to electrode leakage, condensation on the outer wall of the measuring tube or inside the junction box. (2) Measure the insulation resistance between A-C and B-C with an M Ω meter when the lining is dry (it should be greater than 200M Ω). Use a multimeter to measure the resistance between terminals A and B and the two electrodes inside the measuring tube (which should be in a short-circuit connected state). If the insulation resistance is very low, it indicates electrode leakage and the entire flowmeter should be returned to the factory for repair. If the insulation has decreased but still exceeds 50M Ω and the inspection result in step (1) is normal, it may be due to moisture on the outer wall of the measuring tube, and a hot air blower can be used to dry the inside of the shell. (3) Measure the resistance between X and Y with a multimeter. If it exceeds 200 Ω, the excitation coil and its lead may have an open circuit or poor contact. Remove the terminal board for inspection. (4) Check the insulation resistance between X, Y, and C, which should be above 200M Ω. If there is a decrease, dry the inside of the shell with hot air. During actual operation, the decrease in coil insulation will lead to increased measurement errors and unstable instrument output signals. (5) If it is determined that the sensor has a fault, please contact the electromagnetic flowmeter manufacturer. Generally, it cannot be solved on site and needs to be repaired by the manufacturer. If it is determined that the converter is faulty during the converter inspection and there are no external issues, please contact the electromagnetic flowmeter manufacturer. The manufacturer usually solves the problem by replacing the circuit board. Before using an electromagnetic flowmeter, it is necessary to calibrate the flowmeter with a standard pH solution. After calibration, before operation, everyone must pay attention to cleaning the electrodes of the electromagnetic flowmeter with distilled water first, and then cleaning the electrodes again with measuring solution. If the electromagnetic flowmeter is not used, when removing the electrode of the electromagnetic flowmeter, everyone should be careful not to let the tactile sensor of the electrode collide with a hard object, otherwise any damage will affect the use of the electrode. After using the electromagnetic flowmeter, everyone should put the electrode of the electromagnetic flowmeter on the sleeve and put less saturated solution inside. As long as the electrode bubbles are moist, it is enough, but remember not to soak them in distilled water. 4. It is important to keep the electrodes clean and avoid short circuits on both sides of the output, as this may result in inaccurate measurements and affect the use of the electromagnetic flowmeter. In fact, there are many methods to maintain the electrodes of an electromagnetic flowmeter. Everyone should pay more attention during use and not let their small negligence cause the electromagnetic flowmeter to malfunction in the future. Fault analysis 1. Debugging period faults usually occur during the instrument installation and debugging stage. Once eliminated, they will not occur again under the same conditions in the future. Common debugging failures are usually caused by improper installation, environmental interference, and fluid characteristics. 1. In terms of installation, faults are usually caused by incorrect installation positions of electromagnetic flow sensors, such as installing the sensor at the highest point of a piping system that is prone to gas accumulation; Or installed on vertical pipes from top to bottom, which may result in emptying; Or there is no back pressure behind the sensor, and the fluid is directly discharged into the atmosphere, forming a non full tube inside the measuring tube. 1. In terms of environment, it is usually mainly caused by stray current interference in pipelines, strong electromagnetic wave interference in space, and magnetic field interference in large motors. Good separate grounding protection can usually achieve satisfactory results for pipeline stray current interference, but if encountering * stray currents (such as electrolytic workshop pipelines, sometimes the peak AC potential Vpp induced on the two electrodes can be as high as 1V), additional measures need to be taken and the flow sensor needs to be insulated from the pipeline. Space electromagnetic wave interference is generally introduced through signal cables and is usually protected by single-layer or multi-layer shielding. 1. In terms of fluid, the presence of uniformly distributed small bubbles in the measured liquid usually does not affect the normal operation of the electromagnetic flowmeter. However, as the bubbles increase, the output signal of the instrument will fluctuate. If the bubbles are large enough to cover the entire electrode surface, they will cause the electrode circuit to break instantly as they flow through the electrode, resulting in greater fluctuations in the output signal. When an electromagnetic flowmeter with low-frequency square wave excitation measures a slurry with excessive solid content, it will also generate slurry noise, causing fluctuations in the output signal. When measuring mixed media, if it enters the flow sensor for measurement before the mixing is uniform, it will also cause fluctuations in the output signal. Improper selection of electrode materials and the measured medium can also affect normal measurements due to chemical reactions or polarization phenomena. Electrode materials should be selected correctly according to the instrument selection or relevant manuals. 1. Malfunctions during operation | Brand

series

model

|Product Name

by PROHUB

003020 D40 30/30

PROHUB

120557 D73 2-FACH

PROHUB

002973 LR 085 KL 90

PROHUB

16124-FL

PROHUB

002990 GE 040 KL 90

by PROHUB

| 002909 D60-300

PROHUB

002999 GE 060 KL 120

PROHUB

16123-FL

PROHUB

120557 D73 2- FACH

by PROHUB

003020 D40 30/30

PROHUB

090-060-012F

PROHUB

17213- FL

PROHUB

4035910

by PROHUB

17082B08

PROHUB

PH-Y12 -0002- 1

PROHUB

PH-Y120002-16

PROHUB

PH-Y12-0002- 16A

PROHUB

B0101 14022-3-7

PROHUB

20108-ST

bearing housing

PROHUB

20108CO2

drive shaft

PROHUB

PH-Y12-0002-17

PROHUB

090030007

by PROHUB

003028

PROHUB

20108- KA

|Universal shaft

PROHUB

090010045

Roller assembly

PROHUB

090060020

Bearing assembly

PROHUB

20107-FL

belt

PROHUB

090-060-004

PROHUB

090060021

Bearing assembly

SIBA2021113.20

COGSDILLSRMR-31-03

BRINKMANNBFS 232-KH

EUCHNERCES-A-AEA-04B 072000

WOERNERAB31-14/2-1A2A

ALLEN-BRADLEYVPL-B1303F-PJ12AA

BIJUE ELIMONPVB16A03AAAAAAAA00

JBW404.867.0010 DCK31

FHFFHF21225113

ETAEM12-T01-001-DC24V-4

ZF4152.062.018 PG 500/1

ServicesAG 750 50(￠19*118)

ServicesAFJ 50 038V1(￠50*150)

ServicesAFJ 70 015V1(￠19*72)

JOSTJ0EST-TK5230VAC-5A

SARTORIUSPR6211-11

ROLANDP42AGS P.N.S0002800

AVENTICS0821300856pressure regulating valve

MAIERDXSR 265 K-50rotary joint

AG.70HE652FV50A2R-AC230Vlimit switch

WIXROYD32810.W0001

KTRBOWEX-COUPLING 117038-24-8020

KTRBOWEX-COUPLING M-24

BAUERBF70Z-44/DPE09XB4C-S/ESX027A9/SP

SCHMERSALAZ17/170-B5

SCHMERSALAZ 17-11ZK

SCHUNKINK80/S 0301550

SCHUNKBBCK8758 ID:1328053

CHERRYG84-4400LPBUS-2

TAPPKEMER-MATRIXQWS-7000/4-30-L

RSF ELECTRONICBE4360731129

EWO423.294

EWO334.411

OPTRON3874460

ASC102850 BL25M-U-3-350-B-RF (executed according to nameplate 91236) quotation valid until August 10, 2022

WILDENP.025/PPPPP/WFS/TF/PWF

SCHMERSAL103013814 SLB240-R-1-ST

SCHMERSAL103013806 SLB240-E-1-ST

EATONFAK-S/KC11/I

PILZ777314

EUCHNER082122 NZ1VZ-3131E-M

REMECH17-4132-1122.47

SCHMERSAL1NO+1NC，ZFH232-22

IFMIFS244

IFMIFS240

DatasensorS15-PA-2-C10-PK

BUCHERSDRB-P-10-SM

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MAXON118889+166943

MAXON283858+363974+301212

MAXON283858+144006

PATLITECLF10-24

TRIDH130-00002

GEA4443-0804-020

GEA4443-0804-021

GEA4443-0804-022

GEA4443-0804-023

AUMASA14.1 A101432

JUMO90/00559222

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SCHUNK302223 A-SWK-011-ISO-A50

LUBRIPLATE LUBRICANTSSFGO ULTRA 32

Buschjost8497277.9668

OTT9560007392

OTT9560148392 ADAPTER PSC 80

D+PDP-K-003-000018 + DP-K-003-000054

BUHLERNT 63-KN-VA-M3/240

BUHLERNT 63-KN-VA-M3/500

BEMERS130-41-22.3

SPECKIVD-360-MK-400V replacement

BRINKMANNBFS238/40-61KBT5Z+415

BALTECP rne 181 HPP ang D 160772 a

BAUMERMDFK 08G2101/0500

Language14570692 MW-XXUS - 0...200 MBAR - 1/4 NPT-F - 1/2 -14 LT

VVCDSLbutterfly valve

ATOSA1Y-HA32B

ATOSSCLI-40317

ATOSSCLI-4033/1

ATOSLIDEW2-4-I10P12A

PROMINENTThe quotation for S1BA S1BAH10050PVTS000M000 is valid until August 13, 2022

CELSADSA12-NS40/P1R-01

GEMU88029346

DINSE62903N0004 1503406

COGSDILLSRMR-31-03

HMSAWB3000

SCHNEIDERATS448C41Q

ASCON TECHNOLOGICXP-3000/99

MAC1353G-611D-3 M0D:AL01solenoid valve

HOFMANN619161 75

HOFMANN656050 1600

HOFMANN647050 55

AVTRONHS40ZT6MG6W903S

STERLINGLPHX 45311 AB

HYDAC0280D005ONfilter element

HYDAC0240D005ONfilter element

HYDAC0030D025Wfilter element

MEISTER45XM1030XG20WH

LOVATOG48111auxiliary contact

KARL STORZTC-302-03G2H39425

GRUNERUL-721Q-R1A-BO32

PULSOTRONIC08430131055 CSK087A-LDR

SARTORIUSPR6211-11

RebsVEG8/7

RebsVEU8/3

RebsVEG6

JOSTJ0EST-TK5230VAC-5A

BOLZEN1259637 5333655

KRIWANSE-E1 347017-10

KRIWANOLC-D1 L=100

PILZ777301

PILZ774314

IFMSBG233

IFMIGT215

IFMOJ5031

E+L00352056-FR 6011

E+L00352034-OL 8221

AVTRONHS40ZT6MG6W903S+5M

TRIDH130-00002

PREVOSTMT RA1063

FORMAT92571015

SCHNEIDERThe quotation for ATV650C31N4F is valid until August 13, 2022

NUMATICSA51BA452CG60S61 24VDC

SCHNEIDERXS618B1MAL2 quotation is valid until August 1, 2022

KUEBLER8.5000.B352.2048

AUTONICSBEN5M-MFRphotoelectric switch

WENGLORCP24MHT80

OLIVER VALVESCHECK VALVE CV75S 316SS,6000PSIcheck valve

PILZ541011

PILZ541012

PILZ541009

RITTALSZ 4140.830

RITTALSZ 4315.800

STARSH736001A0727

SEWMC07B0008-5A3-4-00

RUWAC10003683

RUWAC968001F

RUWACFL-90870A134515D

RUWACFL-90870A234515E

RUWAC35211UL

SOLAHDSTV25K-24S

PREVOSTBAL 2040B

ROLANDNKAS-W DELIVERY LENGTH PER PIECE 10 M

ROLANDA100

ROLANDTN15S SENSOR-WITHOUT CABLE

SCHMALZ10.02.02.04521 SCPI-FS 25 NO RP M12-5 Replacement

GEMU610 12D 1 5 211/N 88015108

ATSSP179 266.70X304.80X17.45 L2M FKMskeleton oil seal

EMETAMA215-12-0060-40

RITTALSK 3214.100

PEWAG4031538 (A46118) RK 1623-1X15.875X9.65 DIN8187 21.15-meter quotation valid until July 29, 2022Roller chain

SCREENVP-3/1.0/P/112/130/1.0

HELUCKELMULTIFLEX 512-PUR 7G1.0，22527

HELUCKELMULTIFLEX 512-C-PUR 5G1.0，22596

RebsVEU 8/3

RebsVEG 8/7

RebsVEG 6

SAACKES060020002 F-OSA

NORDSON1056119 24VDC,5.4W,LED

KYTOLASLM13-F

MASTERWATT75030030D000004

BRONKHORSTM13V14I-AGD-33-K-S

WALTHER1-SP-006-2-WR017-11-2

LEGRIS7883 06 10

LABOMCE6110 A1060H1K1010 T420Pressure transmitter

ROSSEL0-0354-00095-11

ROSSEL0-0355-00079-11

ROSSEL2-7223-00302-11

ROSSEL2-4006-01891-11

ROSSEL2-6003-00142-11

RITTALSZ 4140.830

RITTALSZ 4315.800

IFMECV932

IFMECV933

VEMIE3-W41R 80 G 4 替代

MAYR8225258, up 5% on August 1st

BLACK BOXACU5050A-R2

JUMO8467343

SCHUNK39303313 PZN-PLUS 125-1-V

P+FENI58IL-H10BA5-1024UD1-RC1encoder

P+FENA58IL-S10CA5-1213B17-ABPencoder

P+FENA58IL-S10CA5-0013B17-ABPencoder

G. BEE0020005001020 + 0020005992015 10998916

G. BEE0020005003020 + 0020005992015

G. BEE0020005992015 11447861

PILZ541010

PILZ541060

UNIVERSAL HYDRAULIKSSPA-5/64-A-N-R-V0-01-AX

P+FENI58IL-H10BA5-1024UD1-RC1encoder

AWH390109000 DN40-65

AWH390112000 DN80-100

ANGELUS2257029

HILMA8-2280-8017 SLOT 28 MM -8-2280-801

HILMA8-2280-8017 SLOT 28 MM

8-2280-8017 SLOT 28 MM

PREVOSTCPI 127710E

BRONKHORSTM14V14I-AGD-33-K-S

CCDGLGE CMG80

SCHOENBUCH2997 OTFS162

STRINGRK 86A DN 200, PN 16, BODY 1.4404

GESINTCLS-A

TURCKBKV8240-0/9

EGELG 518 GSP P11237

VECTORVN1630A

VECTORCANCABLE 2Y

TURCKBI3U-EG12SK-AP6X

ASA HYDRAULIK19434 SAE3 2.1/2063 SDKSS063 quotation valid until August 18, 2022

ETASES582.1

HBMCLY41-350/6

ATLAS660-101401 8202-1350-22 quotation valid for 4 weeks

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ETASES582

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TRCE65M110-02807

MARPOSS3415335200

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VOITH7608458,SIZE 487

SIBANH-125A-GL/GG-GR.00-690V

CARLO GAVAZZIEASSM2310S

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WARNER5200-452-011

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Electromobility torenwerk10102334 replacement

IFE1300779 MODUL 68

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GEMU723 32D 214O4 AE2015

SCHRACKK003418.03 B2FRSV003

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ARPLASAL-S.QCS. QC.02

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APEX15LF081-38

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ABBM2QA132M6B (Installation Method: B5 Vertical)

GEMU88270889 1436000Z1SA010101S01

JUMO60/60002157

ATB100L/2A-11

ADAMCZEWSKIAD-TV810-GS

PHOENIX2700642

E+L00210897-AG 2591

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RINGSPAN3021.011.001.019,95

ElectronHRD 2T FU-95/3.0

KEB19F5A0H-350F

JERGENS25754

HUBA CONTROL525.9220031911

WOERNERKFA-A/O/O/165/135

JERGENS25754

PARKERP7P3L1A9A2A00

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EMGDES 56G 2-771-35W46-SWZ replacement

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PIAB3116063

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TRCEH582M-00135

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AIRPOWERAPS-140/090-10-F10/F12-V27-H

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BELLMER KUFFERATH1000512950

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BAUMERITD 70 A 4 Y 7 1024 H NI H2SK12 S 60 11059642

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SALMSONN0S32/200B-5.5-2-14.2-ABB

ELFIN050F11

ELFIN050S031

BUSSMANN170M3819D

ALLEN-BRADLEY700-HPSXZ24 (pack of 10 pieces)

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ALLEN-BRADLEY440P-MSLB22B

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PARKERD31FHE02C1NB004

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REVORD5012005000000

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AB1734-IB8S

Operational failures refer to faults that occur in electromagnetic flow meters after being debugged and operating normally for a period of time. Common operational failures are mainly caused by factors such as the adhesion layer on the inner wall of the flow sensor, lightning strikes, and changes in environmental conditions. 1. The adhesion layer on the inner wall of the sensor often accumulates due to the use of electromagnetic flow meters to measure dirty fluids after a period of operation, leading to malfunctions. These faults are often caused by the conductivity of the adhesion layer being too high or too low. If the attachment is an insulation layer, the electrode circuit will break and the instrument will not work properly; If the conductivity of the adhesion layer is significantly higher than that of the fluid, the electrode circuit will experience a short circuit and the instrument will not function properly. Therefore, it is necessary to promptly remove the attached scale layer inside the measuring tube of the electromagnetic flowmeter. 1. Lightning strikes can easily induce high voltage and surge current in the instrument circuit, causing damage to the instrument. It is mainly introduced through power lines or excitation coils or flow signal lines between sensors and converters, especially from the control room power lines, which account for the vast majority. During the debugging period, if the environmental conditions are still good (such as no interference source) and the flowmeter works normally, it is often easy to overlook the installation conditions (such as poor grounding). In this case, once the environmental conditions change and new interference sources appear during operation (such as welding on pipelines near the flowmeter, installing large transformers nearby, etc.), it will interfere with the normal operation of the instrument, and the output signal of the flowmeter will fluctuate. Common faults and typical fault diagnosis and treatment 1 No traffic output. Check if there are any faults in the power supply and test if the power supply voltage is normal; Test the continuity of the fuse; Check if the sensor arrow is consistent with the fluid flow direction. If not, change the installation direction of the sensor; Check if the sensor is filled with fluid. If not, replace the pipeline or install it vertically. 2. The signal becomes smaller or suddenly drops. Test whether the insulation between the two electrodes is damaged or short circuited, and the normal resistance value between the two electrodes is between (70-100) Ω; The inner wall of the measuring tube may accumulate dirt, and the electrode should be cleaned and wiped to avoid scratching the inner lining. Measure whether the lining of the measuring tube is damaged, and replace it if damaged. 3. If the zero point is unstable, check whether the measuring tube is filled with the medium and whether there are bubbles in the medium. If there are bubbles, install an air purifier upstream. If it is installed horizontally, it can be changed to a vertical installation; Check if the instrument grounding is intact. If it is not good, a three-level grounding should be carried out (grounding resistance ≤ 100 Ω); The conductivity of the medium should not be less than 5 μ s/cm; Check if the medium has accumulated in the measuring tube, and be careful not to scratch the inner lining when removing it. 4. The flow indication value does not match the actual value. Check if the fluid in the sensor is filled in the tube and if there are any bubbles. If there are bubbles, install an air purifier upstream; Check if all grounding conditions are in good condition; Check if there is a valve upstream of the flowmeter. If so, move it downstream or fully open it; Check if the range setting of the converter is correct. If not, reset the correct range. 5. The displayed value fluctuates within a certain range. Check whether the environmental conditions have changed. If new interference sources or other magnetic sources or vibrations that affect the normal operation of the instrument appear, the interference should be promptly removed or the flowmeter should be moved; Check and test the signal cable, and use insulation tape to treat the end so that the wire, inner shielding layer, outer shielding layer, and shell do not come into contact with each other. The fluid used to measure flow rate with an electromagnetic flowmeter must be conductive, so non-conductive substances such as gases, vapors, oils, and copper cannot be measured with an electromagnetic flowmeter. Operation failure refers to a malfunction that occurs during operation after initial debugging and normal operation for a period of time. Common causes of the malfunction include the adhesion layer on the inner wall of the flow sensor, lightning strikes, and changes in environmental conditions. 1. Due to the fact that electromagnetic flow meters have a much higher chance of measuring suspended solids or pollutants in the inner wall adhesion layer compared to other flow meters, the probability of failure caused by the inner wall adhesion layer is relatively high. If the conductivity of the adhesion layer is similar to that of the liquid, the instrument can still output signals normally, but only change the flow area, resulting in an implicit fault of measurement error; If there is a high conductivity adhesion layer, the electromotive force between the electrodes will be short circuited; If it is an insulating adhesive layer, the electrode surface will be insulated and the measurement circuit will be disconnected. Both of the latter two phenomena will cause the instrument to malfunction. 2. Lightning strikes can induce instantaneous high voltage and surge current in the power line, which can damage the instrument if it enters. There are three ways to introduce lightning damage instruments: power lines, flow signal lines between sensors and converters, and excitation lines. However, based on the analysis of damaged components caused by lightning faults, most of the induced high voltage and surge current that caused the fault were introduced from the power supply lines in the control room, and the other two pathways were relatively few. It was also learned from the scene of the lightning strike accident that not only did the electromagnetic flowmeter malfunction, but other instruments in the control room often experienced lightning strikes at the same time. Therefore, the user unit should recognize the importance of setting up lightning protection facilities for instrument power lines in the control room. The current team of design units has identified and explored solutions to this problem, such as Qilu Petrochemical Design Institute. 3. The main reason for the change in environmental conditions is related to the fault environment during the debugging period mentioned above, but the interference source did not appear during the debugging period and intervened during the operation period. For example, an electromagnetic flowmeter with poor grounding protection may operate normally during the debugging period due to the absence of a factory interference source. However, during the operation period, a new interference source (such as a pipeline near the measurement point or pipeline welding at a distance) may interfere with the normal operation of the instrument, resulting in significant fluctuations in the output signal. Maintenance case of electromagnetic flowmeter: 1. Sensor inspection and testing equipment: one 500M Ω insulation resistance tester and one multimeter. 2. If it is determined that the electromagnetic flowmeter has a converter fault during the converter inspection, and there is no problem with the external cause after inspection, please contact the manufacturer. Generally, the solution will be to replace the circuit board. The practice of measuring low conductivity media with electromagnetic flowmeter. Electromagnetic flowmeter is used to measure the volumetric flow rate of conductive liquid media with conductivity greater than 5 μ s/cm. The measurement principle of electromagnetic flowmeter is mainly based on Faraday's law of electromagnetic induction, which means that when the fluid passes through the measuring tube, it induces electromotive force by cutting the magnetic field lines. The electromotive force is proportional to the magnetic flux density. The product of the inner diameter of the measuring tube and the average flow velocity is measured. The electromotive force (flow signal) is detected by the electrode and sent to the converter through the cable. However, when measuring weak conductivity media, the electromotive force is difficult to be induced. Through on-site practical operation methods, we have summarized the following points for reference: firstly, it is necessary to determine whether the measured medium has conductivity; Secondly, the installation of electromagnetic flow meters should strictly follow the product manual; Once again, when debugging the electromagnetic flowmeter, the parameter of empty tube alarm in the electromagnetic flowmeter converter can be turned off to smoothly detect the electromotive force. The calculation method for determining the diameter of electromagnetic flowmeter: Electromagnetic flowmeter is mainly used to measure the volumetric flow rate of conductive liquids in closed pipelines. The minimum flow velocity of the fluid specified by electromagnetic flowmeter is not less than 0.5m/s, normally between 2-4m/s, and the highest is not higher than 8m/s. Therefore, when choosing the diameter of electromagnetic flowmeter, we should fully consider selecting the appropriate pipeline size while ensuring the measurement accuracy of electromagnetic flowmeter. So how to determine the diameter of electromagnetic flowmeter? Let me briefly introduce how to determine the diameter of an electromagnetic flowmeter? I assume that there is a 500m ³ pool of water that needs to be drained with a water pump within 4 hours. How can I determine what diameter of pipeline to use? The flow range of the flowmeter can be determined based on the parameters required above: 500m ³ divided by 4 hours equals 125m ³/h. The approximate range of pipeline diameter can be calculated through flow rate, which is: π r ² × flow rate (0.5~8m/s)=125m ³/h. By calculation, it is known that to pump out 125m ³/h of water, the diameter range is between 0.075m~0.2975m, i.e. DN80~DN300. Considering the accuracy requirements of electromagnetic flow meters, the optimal flow rate is 2~4m/s. By calculating the diameter range from 0.105m~0.149m, i.e. DN100~DN150, taking into account various factors such as investment, I can determine that DN100 is more suitable. Installation steps for plug-in electromagnetic flowmeter 1 The plug-in electromagnetic flowmeter requires that the user's pipeline should be set horizontally, with at least 5DN in front of the sensor and at least 3DN of straight pipe section behind it. The flow control valve should be located 3DN downstream of the sensor. The pipeline should vibrate significantly, and the inner wall of the pipeline should have no obvious unevenness. 2. First, open a hole with a diameter of 60-62mm directly above the pipeline measurement point. The edges around the circular hole should be smooth, without burrs or gas cutting scars. 3. Unscrew the installation component from the sensor and reliably weld it to the above-mentioned opening. The requirement is to make the lower end of the installation component flush with the inner surface of the pipeline and ensure that there is no leakage Loosen the three locking screws of the sensor and pull out the detection rod and detection head as a whole for later installation. (Note: Users are not allowed to open the connection between the detection head and the insertion rod) 5 Wrap hemp thread lead oil or PTFE tape around the upper thread of the installation component, and then tighten the ball valve and sealant locking mechanism onto it. 6. Slowly insert the detection rod from above, tighten the locking nut slightly, press down on the insertion rod, measure L2 and record L2 dimensions, and the installation is complete. Influencing factors and selection considerations 1. The influence of various media on measurement ⑴ The influence of flow velocity distribution is known from fluid mechanics. When liquid flows in a pipeline, the flow velocity at each point on the cross-section of the pipeline is not equal. However, whether it is laminar or turbulent, after passing through a certain distance of straight pipe section, the flow velocity can become axisymmetric distribution. The flow velocity is maximum at the center of the pipe axis and zero at the pipe wall, with an average flow velocity of V. As long as the flow velocity distribution is symmetrical with respect to the central axis of the measuring pipe, the magnitude of the induced electromotive force generated on the electrode is independent of the flow velocity distribution at each point, but only proportional to the average flow velocity of the measured liquid. Therefore, axisymmetric flow velocity distribution is one of the working conditions that a uniform magnetic field electromagnetic flowmeter must meet. If the velocity distribution is asymmetric relative to the central axis of the tube, although the total flow rate is the same, the induced electromotive force near the electrode is large, so the measured signal is larger than the actual flow rate value. On the contrary, the signal obtained by inducing a small electromotive force at a 90 ° angle to the electrode is smaller than the actual flow rate value, causing measurement errors. Therefore, in order to make the flow velocity distribution axis symmetrical, it is necessary to add a straight pipe section in front of the flowmeter. ⑵ The influence of magnetic field edge effect on measurement. If it is assumed that the magnetic field is always uniform along the flow direction of the fluid, in fact, this means that the magnetic field along the pipe axis is infinitely long. However, the actual magnetic field of the flowmeter is finite in length, so the influence of edge effect generated by finite length magnetic field on measurement must be considered. Assuming the pipe wall is insulated, the magnetic field near the electrode is roughly uniform, and the two ends gradually weaken, forming uneven edges, and finally dropping to zero. In this way, the electric field E inside the liquid is also uneven, which will generate eddy currents. The secondary magnetic flux generated by eddy currents in turn changes the working magnetic flux at the edge of the magnetic field, further disrupting the uniformity of the magnetic field. At this point, the induced electromotive force measured on the electrode is different in magnitude from the induced electromotive force under an infinitely long magnetic field, resulting in an error. If the pipe wall is conductive, the magnetic field edge effect will be more pronounced due to the short-circuit effect of the conductive pipe wall. As the conductivity and wall thickness of the pipe wall change, this effect will also become more pronounced, resulting in an increase in the loss of induced electromotive force on the electrode. For electromagnetic flow meters, it is essential to measure the insulation of the pipe wall, so the pipe wall is usually coated with an insulation layer. If the tested medium contains magnetic substances, the magnetic field edge effect becomes more complex. Due to the presence of magnetic materials, the magnetic field undergoes severe distortion, resulting in measurement nonlinearity. So for liquids containing liquid metal, DC excitation is generally used to reduce magnetic field edge effects. ⑶ The influence of the conductivity of the measured medium. When the input impedance of the electromagnetic flowmeter converter has been increased to measure conductive liquids, it generally does not cause errors due to slight changes in the conductivity of the medium. However, for a certain input impedance of the converter, there is a lower limit value for the conductivity of the measured medium, which cannot be lower than this lower limit value. It is also not allowed for the conductivity of the measured medium to be too high. For example, when the conductivity exceeds about 10-1S/cm, the flow signal will be reduced and the indicated value will be changed, that is, the indicated flow value will be smaller than the actual flow value. When the conductivity of the measured medium is high, the resistance of the external circuit is small. At this time, regardless of how high the input impedance of the converter is, the parallel connection result will depend on this part of the liquid external circuit, thereby reducing the transmission accuracy between the transmitter and the converter. So, for an electromagnetic flowmeter, the measurement is not affected by the conductivity of the medium within a certain range, and the conductivity of the measured medium cannot be too high or too low. If the conductivity of the medium is high, a large eddy current will be generated in the magnetic field edge region, causing secondary magnetic flux and weakening and strengthening the magnetic fields on both sides of the working magnetic field edge region. Therefore, for media with high conductivity, AC excitation should not be used, and DC excitation should be used instead. With the development of electronic technology, the increase in input impedance of converters will inevitably lower the lower limit of the measured dielectric conductivity. 3、 The selection of electromagnetic flowmeter electrode materials for flow sensors. Improper selection of electrode materials and the measured medium may affect normal measurement due to chemical reactions or polarization phenomena. The electrode material should be selected based on the corrosiveness of the measured medium. Select the lining material for the electromagnetic flowmeter based on the corrosiveness, wear resistance, and temperature of the measured medium. Try to choose electromagnetic flow meters with lightning protection function. 4、 Installation of flow sensor 1. Requirements for installation site. When measuring mixed phase fluids, choose a location that will not cause phase separation. When measuring two-component liquids, avoid installing them downstream where mixing is not yet uniform. When measuring chemical reaction pipelines, they should be installed in the fully completed reaction section. 2) Try to avoid negative pressure inside the measuring tube as much as possible. 3) Choose a location with low vibration, especially for integrated instruments. 4) Avoid large motors, transformers, etc. nearby to prevent electromagnetic interference. 5) Places that are easy to implement separate grounding for sensors. 6) Try to avoid high concentration corrosive gases in the surrounding environment as much as possible. 7) The ambient temperature should be within the range of -25-60 ℃, the relative humidity should be within the range of 10% -90%, and direct sunlight should be avoided as much as possible. 8) The liquid should have the required conductivity for measurement, and the conductivity distribution should be generally uniform. Therefore, the installation of flow sensors should avoid areas that are prone to uneven conductivity, such as adding liquid near their upstream, and the liquid addition point should preferably be located downstream of the sensor. 2. The length requirement for the straight pipe section is relatively low for electromagnetic flow meters. For 90o bend pipes, T-shaped tees, concentric reducers, and fully open gate valves, they usually only need to be more than 5 times the diameter length of the straight pipe section from the electrode centerline, not from the sensor inlet connection surface. Valves with different opening degrees require 1OD, and downstream straight pipe sections are 3D. When measuring mixed liquids of different media, the distance between the mixing point and the flow meter should be at least greater than 30D. According to the type of external magnetic field, electromagnetic flow meters mainly have two types: DC and induction. The external constant lower magnetic field B of the DC electromagnetic flowmeter (Figure 2) is perpendicular to the tube axis, and two electrodes are installed at positions C and D to measure the electromotive force U induced by the fluid crossing the magnetic field. The flow rate Q can be calculated using the following formula: