HIGH PERFORMANCE FLOW METERS - Electromagnetic Flow Meters
Electromagnetic flow meters operate on the basis of Faraday’s law of induction. According to this principle, any change in the magnetic flux linked to an electric circuit causes an electromotive force (or voltage) to be induced in this circuit. Experiments demonstrate that the faster the change in the magnetic flux, the higher induced voltage. The induced voltage is therefore directly proportional to the rate of change of magnetic flux with time.
This principle is used in the electromagnetic flow meter to measure the volume flow rate of the fluid. The flow meter typically consists of two electromagnetic coils that are mounted on opposite sides of a non-magnetic measuring tube. Two electrodes are fitted inside the tube to detect the voltage generated by the conducting fluid. Although these electrodes come into contact with the fluid, they do not obstruct its flow. The inside of the measuring tube is lined by an insulating material such as rubber, neoprene, etc. which is resistant to the properties of the fluid. The flow meter also includes an electronic control unit which calculates the flow rate and displays the output.
When current is applied to the coils, they generate an alternating magnetic field across the cross-sectional area of the tube. A fluid flowing through the magnetic field acts as a conductor, and a voltage is induced. The induced voltage is picked up by the electrodes and sent to a transmitter which is either mounted on the flow meter or connected remotely. The transmitter calculates the volumetric flow rate and displays the output.
Calculation of the volumetric flow rate
The induced voltage is calculated using the following equation:
U = B x d x v
Where:
U = voltage induced by the conducting fluid
B = magnetic flux density
d = distance between the electrodes
v = average velocity of the conductor (i.e. fluid flowing in the tube through the magnetic field)↳
Since the magnetic flux density and the distance between the electrodes remain constant, the induced voltage is directly proportional to the conductor velocity. The value of the velocity is used to calculate the volumetric flow rate as follows:
Q = A x v
Where:
Q = volumetric flow rate of the fluid
A = cross-sectional area of the tube
v = flow velocity of the fluid.
Specifications.
- Electrode Material: 316L SS
- Wetted Materials Rubber, PTFE
- Flow Body Material 304 SS & 316 SS
- Flow Velocity .01 - 15 m/s Nominal 0 - 4 m/s
- Accuracy: +/- 0.5% of reading in water.
- Repeatability of +/- 0.15% of reading
- DN6 up to DN2000 available.
- LCD Display
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Temperature:
- Liquid: 14°F (-10°C) to 350°F (180°C)
- Ambient: 14°F (-10°C) to 140°F (60°C)
- Power Requirement: 24 VDC 220VAC;
- Output signals: Modbus RTU, 4–20 mA, and 0-10 KHz for flow rate indication
- Digital communications: Modbus RTU
- Proof Pressure 1.6 MPa, 230 PSIG.
- Display: Flow rate, Flow rate 0-100%, and total flow
- Wiring connection to enclosure size: M20 x 1.5
- Factory Final QC Test Certificate
- Integral Electronics
- Electronics Enclosure: IP65
Magnetic flow meters (MAG flow meters) are volumetric flow meters that operate without any moving parts and are ideal for potable water and wastewater applications as well as ideal for any conductive or water-based clean or dirty fluid. Magnetic flow meters will generally not work with hydrocarbons, distilled water, and many non-aqueous solutions as they require a conductive fluid of 5 micro Siemens/cm min.
