Magnetic Vs Ultrasonic Flow Meter, Which is Better?

Both magnetic flow meter and ultrasonic flow meters have been the main flow devices for precision liquid flow measurement. Thus, it is necessary to know how to select them for different application. 

When select between ultrasonic flow meter and magnetic flow meter, it is necessary to comprehensively consider factors such as fluid characteristics, installation conditions, technical advantages, and cost, etc.

The following questions can help to determine which one is more suitable by effective comparing.

1.Having Different Technologies

Magnetic flow meter is developed on Faraday’s Law of Electromagnetic Induction and can be used for liquid flow only. Not for gas flow measurement.

Ultrasonic flow meter can be made on the principle of transit-time or Doppler technology.Transit-time principle can measure average and clean liquid or gas flow measurement.Doppler technology is suitable for measuring fluids containing solid particles or air bubbles. 

2.Is fluid electric-conduction or Not?

If the liquid is electric conduction (usually conductivity>5US/cm), for example, common water or liquid with ion, both magnetic flow meter and ultrasonic flow meter can be used.

But if fluid is not electric conduction, e.g. oil and chemical solvents and ultra-pure water, magnetic flow meter can’t work, but ultrasonic flow meters are more suitable.

3.Whether Need to Cut Pipe or Not

Ultrasonic flow meter is famous for its clamp-on installing, which means the flow meter doesn’t need to cut pipe and no need to weld. Its installing is very simple, anf just fits the clamp on flow transducers to the surface of pipe, and then the installing is finished.

Magnetic flow meters have inline /insertion transducers and have to  cut pipe. Then require to weld for installing. Thus, if don’t want to cut pipe and welding, clamp on ultrasonic flow meter is almost the sole choice in the market.

4.Installing and Maintenance Cost

Clamp on ultrasonic flow meter doesn’t require maintenance after installing. Meanwhile, the installing of clamp on meter is very simply and doesn’t require any skill, and common people can do it. So the clamp on meter doesn’t require cost to install and maintain.

Magnetic flow meter will be more trouble to install. It requires to cut pipe to meet the requirement of installing space. Meanwhile, it may also require skilled man to weld connecting flanges. And its future maintenance cost will be much more than clamp on ultrasonic flow meter, e.g. The electrode of mag-flow may corrode/scale and needs to be cleaned regularly, etc.

5.Heat Energy Measurement System in HVAC

Compare with magnetic flow meter, transit-time ultrasonic flow meters are more often used as cool/energy measurement in HVAC. The ultrasonic flow meter can easily support Max 150 with low cost. It can support clamp on, insertion or inline installing way. Also the cost of a complete energy system based on ultrasonic flow will be more economical than that on mag-flow.

6.Ultrasonic Flow Meters Have More Advantage for Low Power Consumption Application

The rapid development of Internet of things technology needs a large number of low-power sensors and instruments. Flow meter is no exceptional. Ultrasonic flow has gained quicker and better development than magnetic flow. Technically, ultrasonic flow meter is easier to develop low power consumption. In production, the cost of ultrasonic flow meter is lower. Thus, ultrasonic flow meter has been developed as battery powered ultrasonic water meters and ultrasonic heat meters.

Though magnetic flow meter can be powered by battery, but it usually requires more quantity batteries and battery working life is not so long like ultrasonic flow meter. Meanwhile, its material cost can’t be reduced even though for small size pipe.

7.Magnetic Flow Meter: More Suitable for Serious Waste Water

Here serious wastewater mainly refers to the wastewater contains bigger solid particles or air bubbles. Transit-time ultrasonic flow meter may not work well for the similar application. Doppler ultrasonic flow meters may have a less accuracy. So inline magnetic flow meters are often selected for this kind of application.

8.Pipe Material and Pipe Lining Layer Material

Pipe material is very important for clamp on flow meters. Most of often seen material pipes can be suitable for clamp on flow meter, e.g. plastic pipe (PVC,PE,PP,etc), carton steel, stainless steel, copper, etc. But cement/concrete pipe or pipe with cement lining layer can’t work with clamp on flow meters. For such pipes, it is better to use insertion or inline ultrasonic flow meters and inline magnetic flow meters.

By the comparison above, it can make it clearly to judge which flow meter is more suitable. In a word, if don’t want to cut pipe, clamp on ultrasonic flow meter should be the first choice. If the requirement has no special requirement, ultrasonic and magneitc flow meter are also all right.