Electromagnetic Flow Meters

GAO Tek’s electromagnetic flow meters are a volumetric flow that measures the movement or flow rate of a given volume of fluid and it is express through as an electric signal. Our instruments are also ideal for various applications where there is a low pressure drop and low maintenance is required, its ergonomic design including internal and external offers a simple function for user-friendly use. GAO Tek’s electromagnetic flow meters are reliable, high quality, and inexpensive equipment that provide an accurate measuring for easier inspection or testing. It is compact, easy to carry and portable to allow the user to work in complex conditions and on-site.


The electromagnetic flow meter can also be called as the magnetic flow meter or mag meter. Operations use in the electromagnetic flow meter is based on Faraday’s law of electromagnetic induction. The electromagnetic flow meters can detect the flow of conductive liquids. Although the design of early required a minimum fluid conductivity of 1-5 micro Siemens per centimeter for its operation. As newer designs are being developed, its requirement of a hundredfold is only between 0.05 to 0.1.

The electromagnetic flow meter is made of a non-magnetic pipe that contains an insulating material. A pair of magnetic coils and a pair of electrodes are contained and it penetrates the pipe and along with the lining. When a conductive fluid flows through the pipe, through the magnetic field density which is generated by the coils, a voltage is developed across the electrodes and the amount of voltage depends as predicted by Faraday’s law will become the velocity of the fluid.

The calibration factor can be formed for the magnetic field density and pipe diameter which consist of fixed value, the equation is defined to E=KV. The differences of velocities between different points on the profile are compensated by the signal-weighing factor. The compensation is provided by shaping the magnetic coils so that magnetic flux will be where the signal weighting factor is lowest.

A water calibration is used in each flow tube for the manufacturers to determine each electromagnetic flow meter’s K factor. The K value obtained is valid for any conductive fluid and it remain linear over the entire flowmeter range. Thus, flow tubes it is calibrated at one specific velocity in the flow tubes. This instrument can flow in both directions while reversing direction will change the polarity but not the magnitude of the signal.

A millivolt signal is developing from the voltage at the electrodes then the signal is converted into a standard current (4-20 mA) or frequency output (0-10,000 Hz) near the flow tube. Intelligent magnetic transmitters with digital outputs allow direct connection to a distributed control system. When a transmitter is remote, the electromagnetic flow meter signal is tend to be weak, the lead wire needs to be shielded.

The coils can be powered through the current of alternate or direct. If the AC excitation is used, line voltage is applied to the magnetic coils. A sine wave pattern will be created as a flow signal.

A unique dual excitation has scheme as a newer improvement and in which it creates a pulse to the coils at z and at around 70 Hz to obtain a high signal. The transmitters can be supplied with power. It is possible to use a two-wire, loop powered dc for more safety but with a disadvantage of reduced performance due to power limitations.

If in the electromagnetic flow meter is provided with a level sensor that is embedded in the line, it can also measure the flow in partially full pipes. This design introduces the magnetic electrodes that are located at the bottom of the tube in order to remain covered by the fluid. Calibration is provided for full pipe and filled pipe operation.

Another improvement is the unlined carbon steel flow tube. The measurement of electrodes is mount remotely to the unlined flow tube and the coils create a field 15 times more grounded than in the tube. The main standpoint is low replacement costs.

Electromagnetic flow meters are currently one of the most common used as a type of flow technology for its precise measurement of a liquid flow. The main appeal of the electromagnetic flow meter is it is geared toward the reduction of the PCB area and its exceptional performance thus, it becomes a good choice as an instrument of measurement in many industries.


GAO Tek’s electromagnetic flow meters are reliable, accurate, and easy to use to help prevent failure in operations. It's also:

·         Compact and portable: which are suitable for working aloft and complex conditions

·         Advanced diagnostics that can process conditions

·         Dual compartment housing design

·         Selectable coil frequency

·         Tunable empty pipe diagnostics

·         Simple user interface and easy to use due to easy targeting bright laser

·         High and continuous performance

·         Software included for computer use.

·         Automatic shutdown for saving battery usage consumption

·         Multi-color visual display

·         Accurate and precise

·         Minimum/Maximum function

·         Low battery indication

·         Backlight LCD: reading in dim light conditions

·         PC connect via USB

·         Rechargeable Li-on battery that can last for more than 8 hours of use


The electromagnetic flow meter can be used in various industries such as building automation, marine, power, utilities, paper mills, water and wastewater treatment, oil and gas, pharmaceutical, metallurgy, mining, food, chemicals, and productions.

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