We briefly explain to you the working principle of electromagnetic flowmeters and the differences between the insertion ones and in-line.
On this occasion we are going to talk about insertion and in-line electromagnetic flowmeters. Actually, one of the main differences between both is the method of installation of the instrument in the pipeline where the flow must be measured, since the working principle is the same.
Electromagnetic flowmeters are based on Faraday’s Induction Law and are ideal for measuring liquids in potable water, wastewater or any liquid applications where the liquid is conductive of electrical current and applications where it is required a low pressure drop and low maintenance.
Working principle of in-line electromagnetic flowmeters
For example, series FLOMID of Tecfluid:
When an electrically conductive liquid flows through a magnetic field, perpendicular to the flow direction, it induces a voltage V proportional to the liquid velocity.
Two electrodes in contact with the liquid and positioned perpendicularly to the magnetic field, sense this voltage V, proportional to the average velocity vm of the liquid, which is captured by the electronic converter to be processed and converted into a flow measurement.
V = B ・ vm ・ D
V = Measured voltage in the electrodes
B = Magnetic field
vm = Average liquid velocity
D = Pipe diameter
Working principle of in-line
electromagnetic flowmeters
Working principle of insertion electromagnetic flowmeters
As in the case of series FLOMAT:
When an electrically conductive liquid flows through a magnetic field, perpendicular to the flow direction, it induces a voltage V proportional to the liquid velocity.
Two electrodes in contact with the liquid and positioned perpendicularly to the magnetic field, sense this voltage V.
V = B ・ v ・ d
V = Measured voltage in the electrodes
B = Magnetic field density
v = Liquid velocity
d = Distance between electrodes
Working principle of insertion
electromagnetic flowmeters
An essential requirement for the optimal operation of our electromagnetic flowmeters is that the minimum electrical conductivity is 20 µS/cm. If this requirement is not met, it is possible that we may not be able to measure the flow rate of the liquid.
Is there a difference in accuracy between in-line and insertion electromagnetic flowmeters?
The insertion electromagnetic flowmeters measure the flow velocity in a specific area of the pipe, roughly representative of the section of the entire pipe.
The in-line electromagnetic flowmeters, on the other hand, measure the average speed of the entire pipe section where they are installed.
And here lies the main difference between them; for this reason in-line electromagnetic flowmeters are more accurate than insertion electromagnetic flowmeters.
Let’s talk about some of their main characteristics and options
Both the FLOMID series and the FLOMAT series of Tecfluid have a low pressure drop as well as absence of obstruction elements, allowing the passage of solids without retentions. The assembly can be done in any position, provided that pipe is always full (in vertical pipe upwards flow is recommended). They have low power consumption and do not require too much maintenance.
Do you need more information about their characteristics? Here you will know those of the in line electromagnetic flowmeter series FLOMID and in this other link those of the insertion electromagnetic flowmeter series FLOMAT.
These electromagnetic flowmeters of Tecfluid have, among other options:
- Flow indication
- 4-20 mA and pulse outputs
- totalizer
- 2 alarm outputs
- empty pipe detection
- HART™ and Modbus RTU RS485 protocols
The parts of the instrument in contact with the liquid to be measured can be manufactured in different materials chemically compatible with said liquid and, in addition, in different types of connection to process.
While the series FLOMID adapts to DN3…DN1000 pipe sizes (other on request), series FLOMAT adapts to DN40…DN2000 sizes.
Insertion electromagnetic flowmeter series FLOMAT
In-line electromagnetic flowmeter series FLOMID
Tecfluid has these flowmeters in compact and remote version. They perform the reading independently of the density, viscosity, temperature or pressure of the liquid to be measured. Without moving elements, and high chemical resistance, they allow the passage of solids in suspension.
Both FLOMID and FLOMAT series electromagnetic flowmeters are configurable by means of PC and USB cable using Tecfluid’s Winsmeter software available for downloading at the Download section of our website.
“in-line electromagnetic flowmeters are more accurate than insertion electromagnetic flowmeters”
Most common applications
Finally we can say that electromagnetic flowmeters are widely used in water treatment, an industries as food, pharmaceutical, petrochemical, paper mill, automotive, fertilizer plants, testing machinery, leak detection and chemical monitoring, HVAC … a wide range of sectors but, of course, provided that the liquid to be measured has the minimum conductivity required.
Do you have an application where you think an electromagnetic flowmeter could be suitable but still you have some doubts? Contact with us through our website or call us at +34 93 3724511 and our technical engineers will inform you about.