Electromagnetic Flow Meter for Wastewater: 5 Things to Check Before You Buy

Electromagnetic Flow Meter for Wastewater: 5 Things to Check Before You Buy

Choosing an electromagnetic flow meter for wastewater is not simply a matter of matching the meter to the pipe diameter.

The wrong liner, electrode or meter size can cause unstable readings, rapid wear or unnecessary replacement costs. Before requesting a quotation, check the liquid conductivity, flow range, material compatibility and installation conditions.

Quick Selection Guide

These are general starting points. Final selection depends on the liquid composition, temperature, solids content and operating pressure.

Need a faster selection? Send WIKSTONE the liquid name, pipe size, flow range, temperature and pressure for a recommended configuration.

1. Can the Liquid Be Measured by a Magmeter?

An electromagnetic flow meter, also called a magmeter, measures electrically conductive liquids.

It is commonly used for:

• Water and wastewater

• Sewage and sludge

• Conductive slurry

• Acids and alkalis

• Salt solutions

• Paper pulp

• Conductive food and beverage liquids

It is normally unsuitable for diesel, gasoline, lubricating oil, gases and steam because these media do not provide sufficient electrical conductivity.

Before selecting the meter, confirm the medium name and conductivity. This prevents choosing the wrong measurement technology at the beginning of the project.

2. Do Not Select the Meter by Pipe Size Alone

A DN100 pipeline does not always require a DN100 electromagnetic flowmeter.

The correct meter size depends on:

• Minimum flow rate

• Normal flow rate

• Maximum flow rate

• Required accuracy

• Solids and abrasion

• Acceptable flow velocity

An oversized flowmeter may produce low liquid velocity and unstable readings during normal operation. A smaller meter installed with reducers may provide better low-flow performance.

An undersized meter can increase liquid velocity and accelerate liner wear, especially when measuring abrasive slurry.

For accurate sizing, always provide the three flow conditions rather than only the maximum flow.

3. Which Liner Should You Choose?

The liner protects the measuring tube and isolates the conductive liquid from the metal body. Its chemical and abrasion resistance directly affect service life.

EPDM or Rubber

A practical choice for:

• Clean water

• Raw water

• Cooling water

• Municipal wastewater

• General sewage

This is often the most economical configuration for standard water-treatment applications.

Polyurethane

Better suited to abrasive media such as:

• Mining slurry

• Sand-containing wastewater

• Ore pulp

• Tailings

• Liquids containing hard particles

Polyurethane provides good wear resistance but may not be suitable for strongly corrosive chemicals or high temperatures.

PTFE or PFA

Commonly selected for:

• Acids and alkalis

• Corrosive wastewater

• Chemical dosing liquids

• Higher-temperature conductive liquids

PTFE and PFA offer strong chemical resistance, but highly abrasive media may require another liner.

Simple Liner Decision

• Mainly water: consider EPDM or rubber.

• Mainly abrasion: consider polyurethane.

• Mainly corrosion: consider PTFE or PFA.

• Both corrosion and abrasion: provide full medium details for material evaluation.

4. Which Electrode Material Is Suitable?

The electrodes contact the liquid directly. Selecting an incompatible material may lead to corrosion, signal instability or early failure.

Chemical compatibility depends on concentration and temperature. For corrosive wastewater, do not select electrodes based only on the general liquid name.

For example, “acidic wastewater” is not enough information. The supplier should also know the chemical type, concentration, pH and temperature.

5. Integrated or Remote Transmitter?

An integrated electromagnetic flowmeter combines the sensor and transmitter in one compact unit.

Choose an integrated design when:

• The area is dry and accessible

• Pipeline vibration is limited

• The local display is easy to read

• The transmitter is protected from flooding

Choose a remote transmitter when:

• The sensor is installed underground

• The chamber may be flooded

• The pipeline has strong vibration

• The display must be mounted at eye level

• The installation point is difficult to access

For underground wastewater pipelines, an IP68 sensor with a remote transmitter is generally the more practical configuration.

Common Installation Mistakes

Even a correctly selected electromagnetic flowmeter can produce poor results if it is installed incorrectly.

Avoid these common mistakes:

Installing at the Highest Point

Air can collect at the top of a pipeline and leave the electrodes partially uncovered.

Installing Before an Open Outlet

The pipe may not remain completely full, causing unstable or invalid readings.

Installing Directly on the Pump Suction Side

Low pressure and bubbles may affect measurement performance.

Ignoring Grounding

Incorrect grounding can cause signal fluctuation and zero instability, especially in plastic or lined pipelines.

Using Downward Flow for Slurry

For sludge and slurry, vertical upward flow is generally preferred because it helps keep solids suspended and reduces sediment accumulation.

Three Typical Wastewater Configurations

Municipal Wastewater

A common starting configuration is:

• Flanged electromagnetic flowmeter

• EPDM or rubber liner

• 316L stainless steel electrodes

• 4–20mA and RS485 Modbus

• IP65 or IP68 protection

Abrasive Slurry

Consider:

• Polyurethane liner

• Wear-resistant electrodes

• Remote transmitter

• Suitable flow velocity to control wear

• Vertical upward installation where possible

Corrosive Chemical Wastewater

Consider:

• PTFE or PFA liner

• Hastelloy, titanium or tantalum electrodes

• Chemical-resistant grounding components

• Remote transmitter for harsh environments

• Explosion-proof construction when required

These configurations should be treated as initial recommendations rather than fixed model selections.

WIKSTONE HNLD Electromagnetic Flowmeter

The WIKSTONE HNLD series is designed for conductive liquid measurement in water treatment, wastewater, chemicals, mining, pulp and paper, food processing and other industrial applications.

Available options include:

• DN10–DN2000 pipeline sizes

• Pipeline and insertion types

• Flanged, threaded and sanitary connections

• Integrated and remote transmitters

• PTFE, PFA, EPDM and polyurethane liners

• 316L, Hastelloy, titanium, tantalum and wear-resistant electrodes

• 4–20mA, HART, Modbus and PROFIBUS

• IP65 and IP68 protection

• Explosion-proof configurations

View the WIKSTONE Electromagnetic Flowmeter product page for specifications, material options and available output signals.

Information Needed for a Quotation

To receive a suitable configuration, provide:

1. Liquid name and chemical composition

2. Minimum, normal and maximum flow rate

3. Pipe diameter

4. Process temperature

5. Process pressure

6. Solids content and particle size

7. Required process connection

8. Output and communication requirements

9. Integrated or remote installation

10. IP or explosion-proof requirements

Providing these details helps avoid oversizing, incompatible materials and unnecessary cost.

Frequently Asked Questions

Can an electromagnetic flowmeter measure sewage?

Yes. It can measure conductive sewage and wastewater, including liquids containing suspended solids, provided the measuring tube remains full.

What is the best liner for wastewater?

EPDM or rubber is commonly used for general wastewater. Polyurethane is more suitable for abrasive slurry, while PTFE or PFA is normally considered for corrosive liquids.

Can a magmeter measure diesel?

No. Diesel and most petroleum oils do not have sufficient electrical conductivity for standard electromagnetic measurement.

Does an electromagnetic flowmeter cause pressure loss?

Its full-bore measuring tube contains no internal obstruction, so the meter itself creates virtually no additional pressure loss. Reducers may produce some pressure loss when a smaller meter is installed.

Can it be connected to a PLC?

Yes. Depending on the configuration, the WIKSTONE HNLD series supports 4–20mA, HART, Modbus and PROFIBUS communication.

Choose the Correct Meter Before Ordering

The most important decisions are not the brand name or pipe diameter. They are:

• Is the liquid conductive?

• Is the meter sized for the real flow range?

• Can the liner resist the medium?

• Are the electrodes chemically compatible?

• Will the pipe remain completely full?

Send WIKSTONE your application conditions to receive a recommended electromagnetic flowmeter configuration and quotation.

Contact WIKSTONE

Email: info@wikstone.com
WhatsApp: +86 18255162781

Related WIKSTONE Resources

• Electromagnetic Flowmeter Product Specifications

• Water and Wastewater Instrumentation Solutions

• Industrial Flow Measurement Products