Magnetic Flowmeters for Clean Water

Magnetic Flow Meters for Clean Water

Learn about Magnetic Flowmeters for Clean Water

The QSE Mag Series is a dependable highly accurate
electromagnetic flowmeter designed for flow and usage
monitoring in commercial applications.

The Noryl™ housing and flow tube offer a lightweight, easy-
to-install Mag Meter that is resistant to heat and compatible with many water-based liquid solutions.

The QSE Mag Meter monitors flow rate and total flow in a
wide variety of applications including: HVAC, Turf/ Irrigation
and other water reclamation applications.


  • Low investment and operating costs
  • ± 0.5% Accuracy of Reading (from 0.25 fps to 15 fps [0.08 to 4.6 m/s])
  • Wide turndown ratio of 60:1
  • Non-intrusive, no moving parts to wear out, maintenance, repair costs low and tolerates high flows without damage
  • The slightly modified bore permits unobstructed flow and minimizes flow disturbances and straight pipe requirements
  • 7 line sizes ( 1⁄2”, 3⁄4”, 1”, 1-1/2”, 2”, 3", & 4”)
  • Housing ported with “Thermal Well Supports” for sensors (Energy Management)
  • Compatible with GPI 09 Electronics Display or FLOMEC QSI I/O Board
Price: Starting at $1,022.00
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  • Flow Ranges: 0.16 - 16 GPH to 0.4 - 90 GPM
  • For measuring and monitoring of conductive liquids
  • All-metal design: stainless steel
  • Accuracy: < ±(0.8% of reading + 0.5% of full scale)
  • Flow and temperature measurement
  • Monitoring, transmitter function, batching
  • Bidirectional measuring
  • Max pressure: 230 PSI
  • Max temperature: 284 F


Price: Starting at $697.00
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  • Flow Ranges: 0.18 - 7.8 GPH to 9 - 180 GPM
  • Accuracy: ±2% of Full Scale
  • Max Pressure: 145 psi
  • Max Temperature: 176 F
  • Connection: G 1/2 - G 2 3/4 Male with optional NPT, Socket and Hose Connections
  • Materials: PPS Body with Stainless Steel or Hastelloy® Electrodes; PVDF Body with Hastelloy® or Tantalum Electrodes
  • Electronic Packages: Frequency or Current Outputs, Adjustable Switches, and Integral Totalizers or Batch Controllers


  • No Moving Parts in the Flow Body
  • Low Pressure Loss
  • Universal Mounting
  • High Quality at a Low Price
Price: Starting at $585.00
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Learn more about this technology, the manufacturers, the users and the applications here.
Magnetic Flow Meter for Clean Water

How Magnetic Flowmeters Work

Magnetic flowmeters use Faraday’s Law of Electromagnetic Induction to determine the flow of liquid in a pipe. In a magnetic flowmeter, a magnetic field is generated and channeled into the liquid flowing through the pipe. Following Faraday’s Law, flow of a conductive liquid through the magnetic field will cause a voltage signal to be sensed by electrodes located on the flow tube walls. When the fluid moves faster, more voltage is generated. Faraday’s Law states that the voltage generated is proportional to the movement of the flowing liquid. The electronic transmitter processes the voltage signal to determine liquid flow.

In contrast with many other flowmeter technologies, magnetic flowmeter technology produces signals that are linear with flow. As such, the turndown associated with magnetic flowmeters can approach 20:1 or better without sacrificing accuracy. They represent about 23% of all flowmeters sold.

Plusses and Minuses

Mags are intermediate in accuracy therefore not commonly used for commodity transfer except for some special cases where the fluid is not expensive like water. Can be adapted for sanitary uses. They have large line sizes available. No pressure drop induced. Dirty liquids and even slurries OK. Very reliable. On the other hand, don’t work on nonconductive fluids such as oils. Steam or gas flows don’t register. Electrodes can become coated.

How to Use Magnetic Flowmeters

Magnetic flowmeters measure the velocity of conductive liquids in pipes, such as water, acids, caustic, and slurries. Magnetic flowmeters can measure properly when the electrical conductivity of the liquid is greater than approximately 5μS/cm. Be careful because using magnetic flowmeters on fluids with low conductivity, such as deionized water, boiler feed water, or hydrocarbons, can cause the flowmeter to turn off and measure zero flow.

This flowmeter does not obstruct flow, so it can be applied to clean, sanitary, dirty, corrosive and abrasive liquids. Magnetic flowmeters can be applied to the flow of liquids that are conductive, so hydrocarbons and gases cannot be measured with this technology due to their non-conductive nature and gaseous state, respectively.

Magnetic flowmeters do not require much upstream and downstream straight run so they can be installed in relatively short meter runs. Magnetic flowmeters typically require 3-5 diameters of upstream straight run and 0-3 diameters of downstream straight run measured from the plane of the magnetic flowmeter electrodes.

Applications for dirty liquids are found in the water, wastewater, mining, mineral processing, power, pulp and paper, and chemical industries. Water and wastewater applications include custody transfer of liquids in force mains between water/wastewater districts. Magnetic flowmeters are used in water treatment plants to measure treated and untreated sewage, process water, water and chemicals. Mining and mineral process industry applications include process water and process slurry flows and heavy media flows.

With proper attention to materials of construction, the flow of highly corrosive liquids (such as acid and caustic) and abrasive slurries can be measured. Corrosive liquid applications are commonly found in the chemical industry processes, and in chemical feed systems used in most industries. Slurry applications are commonly found in the mining, mineral processing, pulp and paper, and wastewater industries.

Magnetic flowmeters are often used where the liquid is fed using gravity. Be sure that the orientation of the flowmeter is such that the flowmeter is completely filled with liquid. Failure to ensure that the flowmeter is completely filled with liquid can significantly affect the flow measurement.

Be especially careful when operating magnetic flowmeters in vacuum service because some magnetic flowmeter liners can collapse and be sucked into the pipeline in vacuum service, catastrophically damaging the flowmeter. Note that vacuum conditions can occur in pipes that seemingly are not exposed to vacuum service such as pipes in which a gas can condense (often under abnormal conditions). Similarly, excessive temperature in magnetic flowmeters (even briefly under abnormal conditions) can result in permanent flowmeter damage.

Industries Where Used

In order of usage, water/wastewater industry, chemical, food and beverage, oil and gas (although not for oil and gas fluids but in support of the processes), power, pulp and paper, metals and mining, and pharmaceutical.

Application Cautions for Magnetic Flowmeters

Do not operate a magnetic flowmeter near its electrical conductivity limit because the flowmeter can turn off. Provide an allowance for changing composition and operating conditions that can change the electrical conductivity of the liquid.

In typical applications, magnetic flowmeters are sized so that the velocity at maximum flow is approximately 2-3 meters per second. Differential pressure constraints and/or process conditions may preclude application of this general guideline. For example, gravity fed pipes may require a larger magnetic flowmeter to reduce the pressure drop so as to allow the required amount of liquid to pass through the magnetic flowmeter without backing up the piping system. In this application, operating at the same flow rate in the larger flowmeter will result in a lower liquid velocity as compared to the smaller flowmeter.

For slurry service, be sure to size magnetic flowmeters to operate above the velocity at which solids settle (typically 1 ft/sec), in order to avoid filling the pipe with solids that can affect the measurement and potentially stop flow. Magnetic flowmeters for abrasive service are usually sized to operate at low velocity (typically below 3 ft/sec) to reduce wear. In abrasive slurry service, the flowmeter should be operated above the velocity at which solids will settle, despite increased wear. These issues may change the range of the flowmeter, so its size may be different than the size for an equivalent flow of clean water.

The closest technology to Mag that could possibly handle similar applications more cost effectively would be vortex shedding. They can handle light particulate, have a higher pressure drop, lower rangeability and are slightly less accurate.