Explosion-proof Electromagnetic Flowmeter
The explosion-proof electromagnetic flowmeter is applied in flammable and explosive working conditions. Compared with ordinary electromagnetic flowmeters, it has an extra explosion-proof function and better housing material. It is an inductive instrument that measures the volume flow of conductive media inside pipes based on Faraday's law of electromagnetic induction. It adopts single-chip embedded technology to realize digital excitation, and supports CAN fieldbus. Besides measuring the flow of common conductive liquids, the flowmeter can also measure liquid-solid two-phase flow, high-viscosity liquid flow, and volume flow of salt solutions, strong acid and strong alkali liquids.
Based on Faraday's electromagnetic induction principle, the explosion-proof electromagnetic flowmeter is equipped with a pair of detecting electrodes on the pipe wall perpendicular to the measuring tube axis and magnetic field lines. When conductive liquid flows along the axis of the measuring tube, the conductive liquid cuts magnetic field lines and generates induced electromotive force. The induced electromotive force is detected by the two detecting electrodes, and its value is proportional to the flow rate. The formula is: E=KBVD.
Where:
E－Induced electromotive force
K－Coefficient related to magnetic field distribution and axial length
B－Magnetic flux density
V－Average flow velocity of conductive liquid
D－Electrode spacing (inner diameter of measuring tube)
The sensor transmits the induced electromotive force E as a flow signal to the converter. After amplification, conversion, filtering and a series of digital processing, the backlit dot-matrix LCD displays instantaneous flow and cumulative flow. The converter provides 4～20mA output, alarm output and frequency output, and is equipped with RS－485 and other communication interfaces, supporting HART and MODBUS protocols.
Application Range
The explosion-proof electromagnetic flowmeter is mainly used to measure the volume flow of conductive liquids and slurries in closed pipelines, such as water, sewage, mud, pulp, various acid, alkali and salt solutions, food slurry, etc. It is widely used in petroleum, chemical industry, metallurgy, textile, food, pharmaceutical, paper-making and other industries, as well as environmental protection, municipal administration, water conservancy construction and other fields.
Advantages
1. Simple and reliable instrument structure, no moving parts, long service life.
2. No flow-blocking components, no pressure loss and no fluid blockage.
3. No mechanical inertia, fast response and good stability, applicable to automatic detection, regulation and program control systems.
4. Measurement accuracy is not affected by the type of measured medium and physical parameters such as temperature, viscosity, density and pressure.
5. Different combinations of PTFE or rubber lining and electrode materials such as Hc, Hb, 316L, Ti can meet the requirements of different media.
6. Multiple flowmeter models including pipe type and insertion type are available.
7. Adopt EEPROM memory to safely and reliably store and protect measurement and calculation data.
8. Available in integrated and remote types.
9. High-definition LCD backlight display.
Performance Indicators
| Instrument Accuracy | Pipe type: Class 0.5, Class 1.0; Insertion type: Class 2.5 |
| Measured Medium | Various liquids and liquid-solid two-phase fluids with conductivity greater than 5μS/cm |
| Flow Velocity Range | 0.2～8m/s |
| Working Pressure | 1.6MPa |
| Ambient Temperature | -40℃～+50℃ |
| Medium Temperature | PTFE lining ≤180℃; Rubber lining ≤65℃ |
| Explosion-proof Mark | ExmibdⅡBT4 |
| Explosion-proof Certificate No. | GYB01349 |
| External Magnetic Interference | ≤400A/m |
| Housing Protection | Integrated type: IP65; Remote type: Sensor IP68 (5m underwater, for rubber lining), Converter IP65 |
| Output Signal | 4～20mA.DC, load resistance 0～750Ω |
| Communication Output | RS485 or CAN bus |
| Electrical Connection | M20×1.5 internal thread, φ10 cable hole |
| Power Supply | 90～220V.AC, 24±10%V.DC |
| Max Power Consumption | ≤10VA |
Structure Form
1. Sensor
The sensor is mainly composed of measuring tube, measuring electrodes, excitation coils, iron core, magnetic yoke and housing.
a. Measuring tube: composed of stainless steel tube, lining and connecting flange, serving as the carrier for measuring the working condition of measured liquid.
b. Measuring electrode: a pair of electrodes installed on the inner wall of the measuring tube, perpendicular to the axial flow direction, to generate signals from the measured liquid.
c. Excitation coil: upper and lower excitation coils that generate magnetic field inside the measuring tube.
d. Iron core and magnetic yoke: introduce the magnetic field generated by the excitation coil into the liquid and form a magnetic circuit.
e. Housing: outer package of the instrument.
2. Converter
It is an intelligent secondary meter. After amplifying the flow signal and calculating by single-chip microcomputer, it can display flow rate and cumulative volume, and output pulse, analog current and other signals for fluid flow measurement or control.
3. Product Assembly Type
It is divided into integrated type and remote type.
a. Integrated type: Sensor and converter are installed as one unit.
b. Remote type: Sensor and converter are installed separately, forming a flow measurement system through connecting cables.
c. To meet the measurement requirements of different media, multiple options are available for sensor lining and electrode materials.
Technical Data
| Execution Standard | JB／T 9248—1999 |
| Nominal Diameter | 10,15,20,25,32,40,50,65,80,100,125,150,200,250,300,350,400,500,600,700,800,900,1000,1200,1400,1600,1800,2000,2200,2400,2600,2800,3000 |
| Max Flow Velocity | 15m/s |
| Accuracy | DN15～DN600: ±0.3% of reading(velocity≥1m/s); ±3mm/s(velocity<1m/s) DN700—DN3000: ±0.5% of reading(velocity≥0.8m/s); ±4mm/s(velocity<0.8m/s) |
| Fluid Conductivity | ≥5uS/cm |
| Nominal Pressure | 4.0MPa(DN10～DN80),1.6MPa(DN100～DN150),1.0MPa(DN200～DN1000),0.6MPa(DN1200～DN2000),6.3,10MPa(special order) |
| Ambient Temperature | Sensor: -25℃~+60℃; Converter & integrated type: -10℃~+60℃ |
| Lining Material | PTFE, Neoprene, Polyurethane, F46, Mesh-reinforced PFA |
| Max Fluid Temperature | Integrated type:70℃ Remote type: Neoprene lining:80℃;120℃(specify on order), Polyurethane lining:80℃, PTFE lining:100℃;150℃(specify on order), F46, Mesh-reinforced PFA |
| Signal & Ground Electrode Material | Stainless steel 0Cr18Ni12Mo2Ti, Hastelloy C, Hastelloy B, Titanium, Tantalum, Platinum/Iridium alloy, Tungsten carbide coated stainless steel |
| Electrode Structure | DN300—DN3000 |
| Connecting Flange Material | Carbon steel |
| Ground Flange Material | Stainless steel 1Cr18Ni9Ti |
| Inlet Protection Flange Material | DN65—DN150: Stainless steel 1Cr18Ni9Ti; DN200～DN1600: Carbon steel + Stainless steel 1Cr18Ni9Ti |
| Housing Protection | Remote type sensor with rubber or polyurethane lining DN15～DN3000: IP65 or IP68; Other sensors, integrated flowmeter and remote converter: IP65 |
| Distance(Remote Type) | The distance between converter and sensor shall not exceed 100m generally |
