Magnetic type flow meters are based on the Faraday principle of electromagnetic induction and are used to measure the flow of liquids with conductivity greater than 5µS/cm. The split design is suitable for high-temperature, outdoor, or special environments. The sensor is submersible. The transmitter meets explosion-proof requirements.
This split-mount smart flow transmitter displays instantaneous and accumulated flow rates, and outputs pulse and analog current signals for fluid flow measurement and control.
| Diameter | DN6～DN2200mm |
| Accuracy | 0.5% ~ 2.0% of reading |
| Temp. range | ＜60℃ |
| Flow rate | 0.3～10m/s |
| Electrode | 316,HastalloyB(HB),HastalloyC(HC), Titanium(Ti),Tantalum(Ta),Platinum(Pt) |
| Protection proof | IP67, IP68(suitable for remote type) |
Magnetic Type Flow Meter Features
Specifications
| RS485, GPRS,Hart | |
| Medium | Acid, alkali, salt and other corrosive medium in chemical industry |
| Diameter | DN6～DN2200mm |
| Accuracy | ±0.5% |
| Medium temperature | ＜60℃ |
| Nominal pressure | GB 0.6MPa (DN700～DN2200) |
| GB 1.0MPa (DN200～DN600) | |
| GB 1.6MPa (DN6～DN150) | |
| DIN PN16,PN25,PN40,PN63 | |
| JIS10K,20K,40K | |
| ANSI Class150,Class300,Class600, others can be customized | |
| Flow rate | 0.3～10m/s |
| Straight pipe required | Upstream ≥5DN，downstream ≥3DN |
| Electrode | HastalloyB(HB),HastalloyC(HC),Titanium(Ti),Tantalum(Ta),Platinum(Pt), |
| Tungsten carbide(WC) (For acid and alkali salt solution) | |
| Installation way | Carbon steel flange (standard), Stainless steel flange(optional) |
| Body material | Carbon steel (standard),Stainless steel(optional) |
| Power supply | 220VAC/24VDC/lithium battery |
| Signal output | Pulse and 4～20mA;(if use lithium battery, without signal output) |
| Communication | Carbon steel (standard), Stainless steel(optional) |
| Explosion-proof | No |
| Protection proof | IP65(compact type),IP67,IP68(suitable for remote type) |
| Work environment | Ambient temperature：-20～+60℃，Ambient humidity：5%～90% |
| Power | ＜20W |
Electrode material selection:
| Sodium hydroxide, ammonium hydroxide alkali solution and weak organic acid | Medium |
| 316L | Domestic water, industrial water, raw water, urban sewage, etc. |
| Hastelloy B (HB) | 1. Salt solution (chloride, sodium salt, potassium salt, ammonium salt, sea water, etc.)2. Alkaline solution (such as a concentration less than 50% potassium hydroxide solution) |
| Hastelloy C (HC) | Oxidizing salt solution (Fe+++, Cu++, seawater) |
| Titanium (Ti) | 1. Salt solution (chloride, sodium salt, potassium salt, ammonium salt, sea water, etc.)2. Alkaline solution (such as concentration less than 50% potassium hydroxide solution) |
| Tantalum(Ta) | 1. Hydrochloric acid, sulfuric acid, oxidizing acid, aqua regia 2. Chlorine dioxide, ferric chloride, hypochlorous acid, sodium cyanide, lead acetate, etc. |
| Platinum (Pt) | Acid, alkali, salt solution |
| Tungsten carbide (WC) | Handled neutral industrial sewage and domestic sewage. Resistant to solid particle interference |
Lining material selection
| Lining material | Linner | Temperature | Suitable medium | Diameter |
| Rubber | Neoprene(CR) | -20~60℃ | Slurry, paper pul,p etc. | DN65~DN1600 |
| Natural Rubber(NR) | ||||
| Polyurethane Rubber(PU) | Slurry, paper pulp etc. | DN25~DN500 | ||
| Silicone rubber | -20~180℃ | Water | DN40~DN1600 | |
| Fluoroplastic | PTFE(F4) | -20~120℃ | Corrosive acid-base salt liquid | DN10~DN1600 |
| Teflon F46(FEP) | -40~160℃ | Corrosive acid-base salt liquid | DN10~DN200 | |
| PFA | -40~160℃ | Corrosive acid-base salt liquid | DN10~DN300 |
Integrated vs. Split Structure
An integrated electromagnetic flowmeter combines the sensor and converter into a single, integrated structure. This compact design reduces pipeline installation workload and simplifies installation and maintenance.
A split-type electromagnetic flowmeter consists of a sensor and a converter. The sensor is installed on the measuring pipe to detect fluid flow. The converter, installed at a certain distance from the sensor (usually no more than 100 meters), receives the sensor signal, processes it, and displays and outputs it. This structure allows for flexible placement and combination of the sensor and converter, tailored to specific needs.
Installation of an integrated electromagnetic flowmeter requires simply mounting the entire device on the pipe, eliminating the need for additional wiring. This simple and quick installation method is ideal for applications with limited space or restricted installation conditions.
Installation of a split-type electromagnetic flowmeter requires installing the sensor separately on the pipe and connecting it to the converter via a cable. This installation method is more complex and requires more wiring, but it can be flexibly adjusted to suit the site’s environment.
With its compact structure and advanced communication capabilities, the integrated electromagnetic flowmeter is suitable for applications with limited space and a high demand for data exchange.
Because the sensor and converter can be installed separately, split-type electromagnetic flowmeters are suitable for applications where the on-site measurement environment is poor and remote display is required. For example, in environments with high temperature, high humidity, high vibration, or corrosive gases, split-type electromagnetic flowmeters can ensure the accuracy and stability of measurement data.
The operating principle of an electromagnetic flowmeter is based on Faraday’s law of electromagnetic induction. The two electromagnetic coils at the upper and lower ends of the diagram generate a constant or alternating magnetic field. When a conductive medium flows through the electromagnetic flowmeter, an induced electromotive force (EMF) is detected between the left and right electrodes on the flowmeter tube wall. The magnitude of this induced EMF is proportional to the flow velocity of the conductive medium, the magnetic flux density of the magnetic field, and the conductor width (the inner diameter of the flowmeter tube). Through calculation, the flow rate can be calculated.
The process parameter equation for the induced EMF is:
E=KBV*D
Where:
E – induced EMF;
D – inner diameter of the measuring tube;
B – magnetic flux density;
V – average flow velocity;
K – coefficient related to magnetic field distribution and axial length;
Electromagnetic flowmeters can achieve an accuracy of 0.5% FS, meeting the requirements of most measurement conditions. Of course, the accuracy of electromagnetic flowmeters is also affected by various factors.
Fluid Conductivity
Electromagnetic flowmeters operate based on Faraday’s law of electromagnetic induction. Liquid conductivity affects the magnitude and stability of the induced electromotive force. When the fluid conductivity is too low, the induced electromotive force is weak, and the signal is easily overwhelmed by noise, resulting in increased measurement error.
For example, when measuring low-conductivity fluids such as deionized water, the conductivity may fall below the lower limit of the electromagnetic flowmeter’s normal measurement range, significantly reducing measurement accuracy.
Fluid Velocity Distribution
Ideally, a fluid in a pipeline should exhibit a fully developed, axisymmetric velocity distribution. However, in practice, localized resistance components such as elbows, valves, and reductions or expansions can distort the fluid velocity distribution. This results in uneven velocity at various points within the measuring tube, affecting measurement accuracy.
Fluid Density and Viscosity
Generally, electromagnetic flowmeters measure volumetric flow, which is theoretically unrelated to fluid density and viscosity. However, in certain special circumstances, such as when high-viscosity fluids flow through pipes, wall slip may occur, affecting the flow velocity distribution and, in turn, indirectly impacting measurement accuracy.
Bubbles or solid particles in the fluid
Bubbles in the fluid occupy a certain amount of space in the pipe, reducing the actual volume of fluid involved in the measurement. Furthermore, the movement of bubbles in the magnetic field may generate additional interference signals. Solid particles may abrade the electrodes and lining, affecting the stability of the measurement signal.
Installation Location
The electromagnetic flowmeter should be installed on a straight pipe section where the pipe is filled with fluid and the flow velocity distribution is uniform. Improper installation, such as near areas with strong disturbances such as pump outlets or valves, can cause unstable flow patterns and affect measurement accuracy.
Straight Pipe Length
Depending on the flowmeter diameter and upstream pipe conditions, the upstream straight pipe section is generally required to be 5-10 pipe diameters long, and the downstream straight pipe section is 3-5 pipe diameters long. If the actual straight pipe section length does not meet the requirements during installation, measurement accuracy will be affected.
Pipeline Vibration
Pipeline vibration can cause minute displacements in the electromagnetic flowmeter’s measuring tube and electrodes, resulting in changes in the induced electromotive force (EMF), which can introduce measurement errors.
Stray Current Interference
Principle: Various stray currents may exist in industrial sites, such as those generated by poor grounding and improper cable routing. These stray currents can generate interference signals in the electromagnetic flowmeter’s measuring circuit, affecting measurement accuracy.
For example, if the electromagnetic flowmeter’s grounding system is inadequate near high-voltage equipment, stray currents may enter the measuring circuit through the ground wire, causing measurement errors.
Magnetic Field Interference
Strong external magnetic fields can interfere with the electromagnetic flowmeter’s own magnetic field, changing the strength and direction of the magnetic field within the measuring tube, thereby affecting the induced electromotive force measurement.
Improper Electrode and Lining Material Selection
The electrode and lining materials should be compatible with the chemical properties of the fluid being measured. Improper material selection can cause corrosion to the electrodes and wear or dissolve the lining, affecting the accuracy and stability of the measurement signal.
Instrument Aging and Wear
Over time, electromagnetic flowmeter components such as electrodes, linings, and coils will age and wear. Electrode surfaces may scale and oxidize, linings may thin and crack, and coil insulation may degrade, all of which can affect measurement accuracy.
Temperature Changes
Ambient temperature fluctuations can affect the performance of the electromagnetic flowmeter’s electronic components, coil resistance, and the fluid’s physical properties (such as viscosity and conductivity). These changes in electronic component performance can alter measurement circuit parameters, affecting measurement accuracy.
Humidity Effects
High humidity environments can cause moisture to build up in the electromagnetic flowmeter’s electronic components, degrading insulation performance and introducing measurement errors. Furthermore, humidity can affect the contact resistance between the electrodes and the fluid, hindering measurement signal transmission.
The electromagnetic flowmeter can display both instantaneous and cumulative flow rates. Flow units can be configured according to user requirements.
Volume flow units: m³/s, m³/m, m³/h, L/s, L/m, L/h;
Mass flow units: kg/s, kg/m, kg/h, t/s, t/m, t/h;
Users can select the appropriate flow display unit based on process requirements and usage habits.
Mass flowmeters have a wide range of applications, measuring the flow of various liquid and gaseous media. They are ideal for applications requiring precise mass flow measurement, such as flow measurement in the chemical, pharmaceutical, and food industries.
Electromagnetic flowmeters are suitable for measuring the flow of conductive media such as acids, alkalis, electrolytes, and wastewater. However, they offer limited accuracy for non-conductive media such as liquefied petroleum gas.
Read more about: Mass Flow Meter Vs Magnetic Flow Meter
More Flow Measurement Solutions
Magnetic flow meters are based on Faraday’s law of electromagnetic induction, measuring flow by measuring the electromotive force induced by a conductive liquid in a magnetic field. Their split structure design and PTFE lining provide significant advantages in corrosion resistance and adaptability.
Split structure magnetic flow meters feature separate sensors and converters. The sensor can be placed in high-temperature, high-pressure, or corrosive environments, while the converter is located in a safe area. Signals are transmitted via cables, protecting the electronic components from harsh operating conditions.
Sino-Inst is a professional supplier of magnetic flow meters. If you require flow measurement, please feel free to contact us.