Magnetic Flowmeter Technology

Best Technology Guide to Magnetic Flow Meters

A Magnetic flow meter, also called electromagnetic flow meter, mag flow meter, or magmeters. A magnetic flow meter is a volumetric flow meter that works with principle of magnetic technology. Magnetic flow meters do not have any moving parts. An electromagnetic flowmeter consists of two parts: Electrode (sensor) and Transmitter. Installation types of magmeters could be: Compact, remote, insertion.

Magnetic flow meter is ideal for wastewater applications or any dirty liquid which is conductive or water based. Magnetic flow meters are also ideal for applications where low-pressure drop and low maintenance required. A range of liner materials, electrode options, and line sizes accommodate a wide variety of process application.

What are Electromagnetic Flow Meters?

An electromagnetic flowmeter is an instrument that uses the principle of electromagnetic induction. Magmeters measure the flow of conductive fluid. The electromotive force induced when the conductive fluid passes through external magnetic field.

The structure of the electromagnetic flowmeter is:

magnetic circuit system, measurement conduit, electrode, housing, lining, and converter.

During the measurement, the excitation coil in the sensor is energized to generate a magnetic field. Conductive fluid passes through the magnetic field. Due to the force of the cutting magnetic field lines, tiny induced electromotive forces are generated.

These tiny induced electromotive forces are collected by the electrodes and sent to the converter part of the instrument. Amplify and correct the signal, and then convert it into the corresponding flow data through the formula. Finally display it to the meter or output to the host computer system.

Features of an Electromagnetic Flow Meter

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

2. No obstructing flow parts in the measuring tube. No pressure loss, and the requirements for straight pipe sections are low. Unique adaptability to slurry measurement;

3. Reasonable selection of sensor lining and electrode material. So magmeter has good corrosion resistance and wear resistance;

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

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

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

7. The flow meter is a two-way measurement system. With three totalizers built in: forward total, reverse total, and difference total. It can display positive and reverse flow and has multiple outputs: current, pulse, digital communication , HART;

8. The converter uses surface mount technology (SMT), with self-checking and self-diagnostic functions;

9. Accuracy not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity.

10. No obstruction in the measuring pipe. No additional pressure loss. No moving parts in the measuring pipe. Life of the sensor is long.

11. The induced voltage signal is formed in the entire magnetic field-filled space. And the voltage signal is the average value on the pipe loading surface. The straight pipe section required by the sensor is shorter and the pipe diameter is 5 times the length.

12. Adopts the most advanced single-chip microcomputer (MCU) and surface mount technology (SMT). Reliable performance. High accuracy. Low power consumption, Stable zero point, and convenient parameter setting. Display the accumulated flow, instantaneous flow, flow rate, flow percentage, etc.

13. Two-way measurement system can measure forward flow and reverse flow.

Advantages and Disadvantages

Advantages of electromagnetic flowmeter

1. The range of the electromagnetic flowmeter is extremely wide. The output is only proportional to the average flow velocity of the measured medium. And the flow state (laminar or turbulent) in a symmetrical distribution has no no effect. So, and its measurement range is up to 100: 1, and some even reach the operational flow range of 1000: 1.

2. No obstructing flow parts in the measuring tube of the electromagnetic flowmeter. And the straight straight pipe section requirements are relatively low.

3. The structure of the sensor of the electromagnetic flowmeter is simple. There are no or any throttling parts in the measuring tube that hinder fluid flow. So, it will not cause any extra pressure loss when the fluid passes through the flow meter. And it is one of the flow meters with low energy consumption.

4. The electromagnetic flowmeter has no mechanical inertia and has a more sensitive response. It can measure the instantaneous pulsating flow, and the flow in both directions.

5. The electromagnetic flowmeter is a volume flow measuring instrument. During the measurement process, it is not affected by the temperature, viscosity, conductivity (within a certain range) and density of the measured medium. So, the electromagnetic flowmeter can measure the flow rate of other conductive liquids with ease only after water calibration.

6. The caliber of electromagnetic flowmeters is wide, from a few millimeters to several meters. And China already has real-flow calibration equipment with a caliber of 3m. Laying the foundation for the use and development of electromagnetic flowmeters.

7. It can measure the flow of dirty media, corrosive media and suspended liquid-solid two-way flow. There are no moving parts inside the measuring tube. And only the measuring tube lining and electrodes that touch the measured fluid. Materials of lining and electrodes can be selected according to the properties of the measured fluid. For example, using polytrifluoroethylene or polytetrafluoroethylene as the inner lining can measure various corrosive media. Such as acids, alkalis, and salts. Using abrasion-resistant rubber as the inner lining. Suitable for measuring solid particles with large abrasion Liquid-solid two-way flow of mineral pulp, cement slurry and various suspended liquids. Such as fiber-containing liquid and pulp.

Disadvantages of electromagnetic flowmeter

1. Do not measure gases, vapors, and liquids containing large amounts of gas.

2. It cannot be used to measure liquids with low conductivity or non-conductivity. Such as petroleum products or organic solvents. At present, electromagnetic flowmeters are powerless.

3. Will be affected by the surrounding strong magnetic field.

4. Cannot be used to measure high temperature media. Limited by the lining material and materials of the measuring tube of the electromagnetic flowmeter.

How does a magnetic flow meter work?

Magnetic flow meters use the principle of Faraday’s Law of Electromagnetic Induction to measure the flow rate of liquid in a pipe. In the magnetic flowmeter pipe parts, a magnetic field is generated, and channeled into the liquid flowing through the pipe. Faraday’s Law states that the voltage generated is proportional to the movement of the flowing liquid. A conductor moving through a magnetic field produces an electric signal within the conductor. And the singal is proportional to the velocity of the water moving through the field. As fluid flows through the magnetic field, conductive particles in the fluid create changes. This variation is used to measure and calculate the velocity of water flow through the pipe. When the fluid moves faster, more voltage is generated. The electronic transmitter processes the voltage signal to determine liquid flow.

Magnetic Flow Meter Construction

The structure of the electromagnetic flowmeter is:

A magnetic circuit system,

a measurement conduit,

an electrode,

a housing,

a lining,

and a converter(transmitter).

Magnetic circuit system: To generate a uniform DC or AC magnetic field.

Measuring catheter: To allow the measured conductive liquid to pass through.

Electrode: To lead out an induced potential signal that is proportional to the measurement.

Housing: Made of ferromagnetic material. It is the outer cover of the excitation coil of the distribution system, and isolates the interference of external magnetic field.

Lining: On the inside of the measuring tube and the sealing surface of the flange. There is a complete layer of electrically insulating lining. It contacts the liquid to be measured. And To increase the corrosion resistance of the measuring tube and prevent the induced potential from being short-circuited by the metal measuring tube wall. Mostly are polytetrafluoroethylene plastics, ceramics. That are resistant to corrosion, high temperature and wear.

Converter: Also called a transmitter. To convert the induced potential signal detected by the electrode into a unified standard DC signal, like 4-20mA.

Electrical Conductivity

Conductivity is the ability of a substance to carry a current, and is the inverse of resistivity. In liquids, the conductivity is often measured by the inverse of electrical resistance-conductance. The electromagnetic flowmeter is used to measure conductive liquids. It has a range of electrical conductivity. Only the medium within the range can use the electromagnetic flowmeter.

The premise of using an electromagnetic flowmeter is that the measured liquid must be conductive. The conductivity cannot be lower than the threshold (ie the lower limit). If the conductivity is lower than the threshold value, it will cause measurement error or even cannot be used. Even if it exceeds the threshold value, it can be measured. The threshold value of the general-purpose electromagnetic flowmeter is between 10-4 to (5 × 10-6) S / cm, which varies depending on the model. It also depends on the length of the flow signal line between the sensor and the converter and its distributed capacitance. The manufacturer’s manual usually specifies the length of the signal line, corresponding to the conductivity. Non-contact capacitively coupled large-area electrodes can measure liquids with a conductivity lower than 5 × 10-8S / cm.

The conductivity of industrial water and its aqueous solution is greater than 10-4S / cm. The conductivity of acid, alkali and salt solution is between 10-4 ~ 10-1S / cm. Low-level distilled water is 10-5S / cm, and an electromagnetic flowmeter can also be used. Petroleum products and organic solvents are too low to be used. From the data, we found that some pure liquids or aqueous solutions have high or low conductivity and are considered unusable. Yet, in actual work, they may be used because they contain impurities, which increase the conductivity of the medium.

Induced Voltage

A magmeter utilizes a set of coils and a pair of electrodes for flow measurement. The meter’s coils are driven by the transmitter with an applied current. Once powered, a magnetic field is formed between both coils. When the pipe is full and the fluid begins to flow, the force of the magnetic field causes the negatively and positively charged particles of the fluid to separate as they pass through the magnetic field. This separation causes an induced voltage between the electrodes and sensor.

What is the principle of magnetic flow meter?

The operation principle of a magnetic flow meter or mag meter is based upon Faraday’s Law. Faraday’s Law states the voltage generated is proportional to the movement of the flowing liquid. The transmitter processes the voltage signal to determine liquid flow.

Rosemount explained it to us very well. Let’s take a look

Faraday's Formula

Faraday’s Formula
E is proportional to V x B x D where:

E = The voltage generated in a conductor
V = The velocity of the conductor
B = The magnetic field strength
D = The length of the conductor

To apply this principle to flow measurement with a magnetic flow meter. First is to state that the fluid being measured must be electrically conductive for the Faraday principle to apply.

As applied to the design of magnetic flow meters, Faraday’s Law indicates that:

the signal voltage (E) is dependent on V, B, D.

V is the average liquid velocity ;

B is the magnetic field strength ;

D is the length of the conductor ( which in this instance is the distance between the electrodes).

Electromagnetic Flow Meter Design

Detailed research on the design of electromagnetic flowmeters. Interested users can refer to this article. Electromagnetic Flow Meters: Design Considerations and Solutions. Focuses on the design considerations of implementing an electromagnetic flowmeter architecture as a solution. That simplifies system design, improves performance, and lowers cost and power.

What is a mag meter used for?

The construction of magnetic flow meters is that the only wetted parts are liner and electrodes. Both the wetted parts can be made from materials that can withstand corrosion. So, magnetic flow meters can measure many corrosive liquids and abrasive slurries.

Magnetic flow meter liners and electrodes can be constructed of materials that do not contaminate the liquid. So Magnetic flow meters can be applied in sanitary applications.

Dirty liquids

Applications for dirty liquids are found in:

the water, wastewater, mining, mineral processing, power, pulp and paper, and chemical industries.

Highly corrosive liquids

With proper attention to materials of construction,

the flow of highly corrosive liquids (such as acid and caustic) and abrasive slurries can be measured.

Corrosive liquid applications are commonly found in the chemical industry processes,

and in chemical feed systems used in most industries.

Slurry

Slurry applications are commonly found in the mining, mineral processing, and wastewater industries.

For slurry service, be sure to size magnetic flow meters to operate above the velocity,

at which solids settle (typically 1.5 – 2 ft/sec),

in order to avoid filling the pipe with solids that can affect the measurement and potentially stop the flow

Liquid is feed using gravity

Magnetic flowmeters are often used where the liquid is fed using gravity. Be sure that the orientation of the flowmeter is such that the flowmeter is completely filled with liquid. Failure to ensure the flowmeter is completely filled with liquid can affect the flow measurement.

Vacuum service

Be especially careful when operating magnetic flowmeters in vacuum service. Because some magnetic flowmeter liners can collapse and be sucked into the pipeline in vacuum service. Note that vacuum conditions can occur in pipes that seemingly are not exposed to vacuum service. Such as pipes in which a gas can condense (often under abnormal conditions). Similarly, excessive temperature in magnetic flowmeters

(even briefly under abnormal conditions) can result in permanent flowmeter damage.

How to Use Magnetic Flow meters

The electromagnetic flowmeter consists of two parts: a sensor and a converter.

Magnetic flow meters work Based on Faraday’s law of electromagnetic induction. Magnetic flow meters measure the velocity of conductive.

Magnetic flow meters measure the volumetric flow of conductive liquid with conductivity greater than 5μS/cm.

It is an inductive meter for measuring the volumetric flow of conductive media.

Measuring the volume flow of general conductive liquids,

it can also be used to measure the volumetric flow rate of strong corrosive liquids. Such as strong acid and alkali, and uniform liquid-solid two-phase suspension liquids such as mud, slurry and pulp. Widely used in liquids in pipes, such as water, acids, caustic, and slurries .

Magnetic flow meters do not require much upstream and downstream straight runs. Magnetic flow meters can be installed in relatively short meter runs. Magnetic flow meters typically require:

5-10 diameters of upstream straight run and 5-2 diameters of downstream straight run,

measured from the plane of the magnetic flow meter electrodes.

Industries that Use Magnetic Flow meters

Magnetic flow meters are well suited for a variety of applications across a range of industries including:

Pulp and paper;

Metals and mining;

Water and wastewater;

Food and beverage;

Chemical;

Petrochemical;

Oil and gas.

Typical Applications

The only wetted parts of the magnetic flow meter are the liner and electrodes. Both the liner and electrodes can be made from materials that can withstand corrosion. The straight-through (obstruction less) nature reduces the pressure drop. And the potential for abrasion from the flowing liquid. So, magnetic flow meters can measure many corrosive liquids and abrasive slurries. Magnetic flow meter liners and electrodes can be constructed of materials that do not contaminate the liquid. So, these mag flow meters can be applied when liquid contamination is an issue, such as in sanitary applications.

To avoid filling the pipe with solids that can affect the measurement and stop the flow.

For slurry, be sure to size magnetic flow meters to operate above the velocity at which solids settle (1.5 – 2 ft/sec).

For abrasive service, Magnetic flow meters are usually sized to operate at low velocity (below 5 – 6 ft/sec) to reduce wear. And he flow meter should be operated above the velocity at which solids will settle, despite increased wear.

These issues may change the range of the flow meter, so its size may be different than the size for an equivalent flow of clean water.

Water Flow Meter Types

Water Flow Meters are flow meters measure and show the flow rate of water flow. Water flow measurement is important for inductrial applications, like the wastewater treatment. In principle, water flow meter types are: Electromagnetic (magnetic), Turbine, Ultrasonic, and DP. Coriolis and Oval Gear flow meters can also work for water flow measurement. These water flow meters, optional with digital display, battery, analog or pulse output. Material can be 316 stainless steel or special material.

Wastewater flow meter

Wastewater Flow meters are flowmeters for water and wastewater treatment. Electromagnetic flow meters are suitable for open channel and underground industrial water pipes. Magnetic flow meters can be Remote type, compact type, insertion type. And ultrasonic flow meters are another choice, if you can not change your pipes. Both ultrasonic flow meters and magmeters are inline flow meters.

Sino-Inst offers ultrasonic and magnetic flow meters,

which offer the highest flow meter accuracy and reliability,

as well as long-term stability and a low cost-of-ownership.

Sanitary Flow Meter

Sanitary Flow Meter, also called the tri-clamp flow meter. Sanitary Flow Meters have stainless steel bodies and come standard with Tri-Clover fittings. Sanitary flow meter meets the requirements of the food, and beverage company industries. Sino-Inst’s magnetic flowmeter and turbine flow meters is available in a sanitary version. And allows for use with Output Modules, Sensors and Remote Transmitters.

Application Cautions for Magnetic Flow meters

1. Do not operate a magnetic flowmeter near its electrical conductivity limit. Because the flowmeter can turn off.

2. Provide an allowance for changing composition and operating conditions. This can change the electrical conductivity of the liquid.

3. In typical applications, magnetic flowmeters are sized. So that the velocity at maximum flow is approximately 2-3 meters per second.

4. Gravity fed pipes may require a larger magnetic flowmeter to reduce the pressure drop. So as to allow the required amount of liquid to pass through the magnetic flowmeter without backing up the piping system. Operating at the same flow rate in the larger flowmeter will result in a lower liquid velocity as compared to the smaller flowmeter.

5. For slurry service, be sure to size magnetic flowmeters to operate above the velocity at which solids settle (typically 1 ft/sec). To avoid filling the pipe with solids that can affect the measurement and potentially stop flow.

6. Magnetic flowmeters for abrasive service are usually sized to operate at low velocity (typically below 3 ft/sec) to reduce wear.

Magnetic Flow Mmeter Troubleshooting

After the flowmeter put into operation or after a period of normal operation, it is found that the instrument is not working properly. You should first check the external conditions of the flowmeter. Such as whether the power supply is good. Whether the pipeline is leaking or is not full. Whether there are air bubbles in the pipeline. Aand whether the signal cable Damage. Whether the output signal of the converter (that is, the input circuit of the rear instrument) is open. Do not repair the flowmeter blindly.

No flow output

Check whether the power supply part is faulty.

Test whether the power supply voltage is normal.

Test whether the fuse is on or off.

Check whether the arrow of the sensor is consistent with the fluid flow direction. Such as inconsistently changing the sensor installation direction.

Check whether the sensor is full of fluid, if not full of fluid, replace the pipe or install vertically .

The signal is getting smaller or abrupt

Test whether the insulation between the two electrodes is damaged or shorted.

The resistance between the two electrodes is normally between (70 ~ 100) Ω; dirt may be deposited on the inner wall of the measuring tube.

The electrodes should be cleaned and wiped, and the inner lining should not be scratched.

Measure the pipe lining for damage and replace it if damaged.

The zero point is unstable

Check whether the medium is full of measuring tubes and whether there are air bubbles in the medium.

If there are air bubbles, install a deaerator upstream. If the installation is horizontal, change to a vertical installation.

Check whether the grounding of the instrument is intact. Perform three-level grounding (grounding resistance ≤100Ω).

Check that the dielectric conductivity is not less than 5 μs / cm.

Check whether the medium is deposited in the measuring tube, and be careful not to scratch the inner lining when removing it.

The flow indication value does not match the actual value

Check whether the fluid in the sensor is full of tubes and whether there are air bubbles. If there are air bubbles, install a deaerator upstream.

Check whether the grounding is good.

Check whether there is a valve upstream of the flow meter.

Check the converter range setting is correct, if not, set the correct range again.

The displayed value fluctuates in a certain interval

Check whether the environmental conditions have changed.

If there are new interference sources and other magnetic sources or vibrations that affect the normal operation of the instrument, the interference should be removed in time or the flow meter should be removed.

Test signal cables should be treated with insulating tape for end treatment.

The wires, the inner shield, the outer shield, and the shell do not touch each other.

Magnetic Flow Mmeter Accuracy

The performance of general-purpose electromagnetic flowmeters on the market is quite different. Some have high accuracy and many functions, and some have low accuracy and simple functions. The basic error of the high-precision electromagnetic flowmeter is (± 0.5% to ± 1%) R, and the low accuracy is (± 1.5% to ± 2.5%) FS.

Some models claim higher accuracy, and the basic error is only (± 0.2% ～ ± 0.3%) R. But, there are strict installation requirements and reference conditions. For example, the temperature is 20-22°C. The length of the straight pipe sections before and after is required to be greater than 10D, 3D (usually 5D, 2D). It has even been proposed that the flow sensor should be integrated with the straight straight tubes on the front and back. To perform flow calibration on a flow standard device to reduce the impact of improper clamping. So, when selecting and comparing many models, do not simply look at high precision. Read the manufacturer’s samples or instructions for comprehensive analysis.

How do you install a magnetic flow meter?

The electromagnetic flowmeter is simply composed of a flow sensor transmitter. The electromagnetic flowmeter must be installed at the lowest point of the pipeline or the vertical section of the pipeline. But it must be in the case of full pipe, and the straight pipe section is required to be 5D before 3D to ensure the electromagnetic flowmeter.

This can ensure the use of electromagnetic flowmeters and the requirements for accuracy. The measurement principle of magnetic flowmeter does not depend on the flow characteristics. If there is a certain amount of turbulence and vortex in the pipeline in the non-measurement area

(such as: elbow, tangential flow restriction or a half-open stop valve upstream). It has nothing to do with the measurement. If there is a steady state eddy current in the measurement area, it will affect the measurement stability and measurement accuracy. At this time, some measures should be taken to stabilize the velocity distribution:

1. Increase the length of the straight pipe section before and after

2. Use a flow stabilizer

3. Reduce the cross section of the measurement point.

Installation Considerations

1. Requirements for the external environment

1.1. The flowmeter should not be installed in the place where the temperature changes greatly or the equipment is exposed to high temperature radiation. If it must be installed, it must be insulated and ventilated.

1.2. The flowmeter is best installed indoors. If it must be installed outdoors, it should avoid rainwater pouring, flooded water and sun exposure. Moisture and sun protection measures must be taken.

1.3. The flow meter should be installed in an environment containing no corrosive gas. Ventilation measures must be taken when it must be installed.

1.4. To facilitate the installation, and maintenance. Ample installation space is required around the flowmeter.

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

2. Requirements for straight sections

To improve the effect of eddy current and flow field distortion. The length of the front and rear straight pipe sections of the flow meter is required to be fixed. Otherwise it will affect the measurement accuracy.

3. Requirements for process tubes

The flowmeter has certain requirements on 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 tubes is the same as the inner diameter of the sensor. Aand should satisfy: 0.98DN≤D≤1.05DN (where DN: sensor inner diameter, D: process tube inner diameter)

b. Process tube and sensor must be concentric, coaxial deviation should not be greater than 0.05DN

4. Requirements for the bypass

To facilitate the maintenance of the flowmeter, it is better to install a bypass pipe for the flowmeter. Besides, if the heavily polluted fluid and the flowmeter need to be cleaned and the fluid cannot be stopped, a bypass pipe must be installed.

a. Convenient flowmeter maintenance

b. Must be installed for heavily polluted fluids

c. Fluid cannot be stopped and the flowmeter needs to be cleaned

5. Installation requirements for Insertion Magnetic Flow Meters

3.1. Requirements for straight pipe sections

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

3.2. Requirements for grounding points

To make the instrument work reliably and improve the measurement accuracy. It should not be affected by the external parasitic potential. The sensor should have a good grounding, and the grounding resistance is less than 10. Location requirements as shown.

Electromagnetic flowmeter installation specification requirements precautions:

1. Where there is no vibration or strong electromagnetic field (such as large motor and inverter);

2. As far as possible vertical installation. Horizontal installation needs to be installed in a low place. Can not install the pipe apex. Ensure full pipe. Prevent air bubbles;

3. Straight pipe requirements, it is best to ensure 5 times the diameter of the first 10;

4. When welding, please pay attention not to connect the instrument to prevent damage to the flowmeter;

5. The shell should be grounded as far as possible. The shielded wire should be grounded at one end, and the point can not be shared with the strong electricity;

6. If it is convenient for maintenance, the installation location needs to be selected to meet the maintenance requirements. At the same time, the side pipe can be installed, and the fluid moves along the side pipe when the fault occurs;

7. To avoid direct sunlight, high temperature, will degauss;

8. Other requirements should be considered, the signal wiring should not be with the strong electric line.

Grounding requirements

The grounding of the electromagnetic flowmeter is very important. For the sensor to work properly, it must have a good separate ground wire. The copper core area is 16mm2, and the grounding resistance is <100Ω.

1. If the pipeline connected to the electromagnetic flowmeter is insulated. A grounding ring of the same material as the electrode material should be selected. If a medium with abrasive properties is measured, a grounding ring with a neck should be selected.

2. When the electromagnetic flowmeter is installed in plastic pipes or pipes with insulating coating or lining on the inner wall. Grounding rings must be installed at both ends of the flowmeter. If a multi-motor structure is used, the grounding ring may not be used.

3. The electromagnetic flowmeter is installed on the cathodic protection pipeline. Pay attention to that the grounding ring and the flange on the pipeline should be insulated. Because the electrolytic corrosion protection pipeline is generally insulated on its inner and outer walls.

Why does a magnetic flow meter need grounding?

The electromagnetic flowmeter signal is weak, only 2.5~8mv at full scale. Only a few microvolts when the flow rate is very small, and slight disturbance will affect the measurement accuracy.

So, the transmitter casing, shielded wire, measuring conduit and transmitter of the pipes. They must be grounded, and the grounding points should be set separately. They must not be connected to common ground lines such as motors and electrical appliances or to the upper and lower water pipes.

The converter part has been grounded through the cable, so do not ground again to avoid interference caused by different ground potentials.

Magnetic Flow Meter Calibration

Quick calibration of electromagnetic flowmeter:

1. Select the corresponding pump according to the diameter and flow rate of the pipeline for the verification test;

2. After the flowmeter is correctly installed and connected, it should be powered on and warmed up for about 30min. According to the requirements of the verification regulations;

3. If a high-level trough water source is used, check whether the overflow signal of the stabilized water tower appears. Before the formal test, according to the requirements of the verification regulations. Use the verification medium to circulate in the piping system for a certain period of time. And at the same time check whether there are leaks in the sealed parts of the piping;

4. Before starting the formal verification, the verification medium should be filled with the sensor of the flowmeter under test. And then the downstream valve should be closed for zero adjustment;

5. At the start of the inspection, the valve at the front of the pipeline should be opened first. And the valve behind the flowmeter to be inspected should be slowly opened to adjust the flow at the verification point;

6. During the calibration process, the flow stability of each flow point should be within 1% to 2%-the flow method, and the total amount can be within 5%. The temperature change should not exceed 1°C. When completing the verification process at one flow point, and should not exceed 5 ° C when completing the verification process;

7. After each test, the valve at the front of the test pipeline should be closed first. And then the pump should be stopped to avoid emptying the voltage stabilization facilities. At the same time, the remaining verification medium in the test pipeline must be emptied. And the control system and the air compressor should be shut down.

Electromagnetic Flow Meter Diagram

How to check magnetic flow meter

You only need to perform periodic visual inspection of the instrument. Check the surrounding environment of the instrument. Remove dust and dirt. Ensure that no water and other substances are ingress. Check whether the wiring is good. And check whether there are newly installed strong electromagnetic field equipment. Or newly installed wires across the instrument near the instrument. If the measurement medium easily stains the electrode or deposits or scales in the measuring tube wall. It should be cleaned and cleaned regularly.

After the flowmeter put into operation or after a period of normal operation, it is found that the instrument is not working properly. You should first check the external conditions of the flowmeter. Such as whether the power supply is good. Whether the pipeline is leaking or is not full. Whether there are air bubbles in the pipeline. And whether the signal cable Damage. Whether the output signal of the converter (that is, the input circuit of the rear instrument) is open. Remember not to repair the flowmeter blindly.

Sensor check

Test equipment: one 500MΩ insulation resistance tester and one multimeter.

Test steps:

(1) When the pipeline is full of medium, use a multimeter to measure the resistance between terminals A, B and C.

The resistance between A-C and B-C should be large. If the difference is more than 1 time, it may be that the electrode is leaking. And the outer wall of the measuring tube or the condensed water is adsorbed in the junction box.

(2) When the lining is dry, use an MΩ meter to measure the insulation resistance between A-C and B-C (should be greater than 200MΩ). Then measure the resistance between A and B. And the two electrodes in the measuring tube (should be in a short-circuit connection). If the insulation resistance is very small, it means that the electrode is leaking. And the whole flowmeter should be returned to the factory for repair. If the insulation is reduced but still more than 50MΩ, and the inspection result of step (1) is normal. The outer wall of the measuring tube may be damp, and the inside of the shell can be dried with a hot air fan.

(3) Use a multimeter to measure the resistance between X and Y. If it exceeds 200Ω, the excitation coil and its lead-out wire may be open or have poor contact. Remove the terminal board and check.

(4) Check that the insulation resistance between X, Y and C should be above 200MΩ. If it decreases, dry the inside of the case with hot air. In actual operation, the decrease of the coil insulation will cause the measurement error to increase and the instrument output signal to be unstable.

(5) If it is determined that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. Generally, it cannot be resolved on site, and it needs to be repaired by the manufacturer.

Transmitter check

If it is determined that the converter is faulty and No problem after checking the external cause. Please contact the manufacturer of the electromagnetic flowmeter. And the manufacturer will generally take the solution of replacing the circuit board.

Magnetic Flow Meters for Wastewater

Sino-Inst offers ultrasonic and magnetic flow meters,

which offer the highest flow meter accuracy and reliability,

as well as long-term stability and a low cost-of-ownership.

Magmeter Selection

The key questions which need to be answered before selecting a magnetic flow meter are:

Is the fluid conductive or water based?
Is the fluid or slurry abrasive?
Do you require an integral display or remote display?
Do you require an analog output?
What is the minimum and maximum flow rate for the flow meter?
What is the minimum and maximum process pressure?
What is the minimum and maximum process temperature?
Is the fluid chemically compatible with the flow meter wetted parts?
What is the size of the pipe?
Is the pipe always full?

Magnetic Flow Meter Options

Sino-Inst offers a comprehensive line of magnetic flow meters, including:

General purpose mag meter
Battery-powered mag meter
High pressure mag meter
Mag meter with integrated BTU measurement
Ceramic-lined mag meter
Insertion mag meter

Wide array of product offerings. Allows users to select a magnetic flow meter for applications in many different industries. From factory automation, food and beverage processing to mining.

Municipal/wastewater treatment, and pulp and paper production.

Insertion Magmeters

Insertion Magnetic Flow Meter, also called Insertion type Electromagnetic flow meter. Insertion style flow meter, measures the flow velocity of conductive liquids in large diameter pipes.

Insertion magnetic flow meter, with easy installation, is suitable for use with conductive fluids,

including water, raw sewage, wastewater, clarified water, RAS, and WAS. Available process connections include hot-tapped, DIN and NPT threads

Insert the electromagnetic flowmeter according to the situation of the pipeline. The flowmeter without ball valve should be installed on the pipeline without overpressure

(that is, the flowmeter without ball valve can be selected for non-pressure installation).

The diameter of the hole in the pipe is 50, and the connection welded pipe is ready to be welded to the opening of the pipe;

For the occasions requiring continuous flow loading or unloading or the medium is not allowed to overflow.

A ball valve must be installed, that is, a plug-in electromagnetic flowmeter with a ball valve structure is selected;

The diameter of the hole in the pipe is 50, and the connecting welded pipe is to be welded to the opening of the pipe.

Selection of plug-in electromagnetic flowmeter

Measuring range: Recommended use range: 0.5m / s ～ 10m / s continuously adjustable. Maximum use range: 0.2m / s ～ 15m / s continuously adjustable

Signal output:

1. The switching value can be set as: pulse output (up to 1000HZ); high / low flow alarm; air pipe alarm; flow direction indication; fault alarm;

2. Current output: 4-20mA output

Configuration mode:

1. On-site configuration through three manual keys.

2. Field configuration via remote control.

3. On-site configuration through the Communicator.

Magnetic Flow Meter Price

Everyone knows that the electromagnetic flowmeter can only measure conductive media. It cannot be measured for media that cannot conduct electricity. Several factors that affect the price of electromagnetic flowmeters are the medium and the caliber. Electromagnetic flowmeters are widely used. Such as: clean water, sewage, various acid and alkali salt solutions, mud, mineral pulp, pulp, and food (hygienic electromagnetic flowmeter) liquids.

For example, the medium measured by the DN100 magnetic flowmeter is acid, the reference price is 495 US dollars per unit, and the medium water is 400 US dollars per unit.

Factors affecting the price of electromagnetic flowmeters are:

1. Structural method. The structure of different electromagnetic flowmeters is greatly different in price. The electromagnetic flowmeters are divided into integrated electromagnetic flowmeters and split electromagnetic flowmeters.

2. Raw materials and lining materials. Different raw materials will bring different prices for electromagnetic flowmeters. Such as carbon steel, 304 and 316, and lining materials such as rubber, PTFE, PFA, polyurethane, etc .;

3. Electrode materials. Electrode materials for electromagnetic flowmeters are mainly stainless steel, titanium, tantalum, platinum electrodes, etc.

4. Connection method. The connection method of the electromagnetic flowmeter is pipe type / plug-in type. And the pipe type is divided into flange connection, clamp connection and flange clamping type;

5. Output signal method. The output signal method will also affect the price of electromagnetic flow meters, such as pulse signals and current signals;

6. Communication method. The 485 communication method, 232 communication. And HART communication are still used for the electromagnetic flowmeter. They are still MODEBAS communication methods.

The closest technology to Mag that could possibly handle similar applications. More cost effectively would be vortex shedding. They can handle light particulate, have a higher pressure drop, lower rangeability and are slightly less accurate.

Magnetic Flow Meter Manufacturers

Sino-Inst is a Professional flowmeter manufacturer from China. Sino-Inst offers over 100 flow meter products. About 30% of these are magnetic flow meters, and others are turbine, vortex, ultrasonic, and mass flow meters. A wide variety of flow meter options are available to you, such as free samples, paid samples.

In order of usage, water/wastewater industry, chemical. Food and beverage, oil and gas (although not for oil and gas fluids but in support of the processes). Power, pulp and paper, metals and mining, and pharmaceutical.

Magnetic flow meter PDF

Sino-Inst offers free catalog for flow meters. You can contact us for magnetic flow meter PDF.

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