IoT Use Case

Industrial Flow Meters and Flow Sensors for IoT

An industrial flow meter measures how much liquid or gas flows through a pipe per unit of time, as volume or mass flow. Depending on the medium, flow sensors use electromagnetic, Coriolis, ultrasonic, vortex or variable area principles. In the IoT stack, they supply consumption and process data for energy monitoring, dosing and leak detection.

  • Co-Founder & CTO/CPO, Greenlyte Carbon Technologies
  • Magna Exteriors (Meerane) GmbH, Manager Automation, Magna
  • Salzgitter Flachstahl

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Who offers it

Flow sensors in practice

2 manufacturers from our partner network with 34 solution examples. Those with the most documented use in this category come first.

What it is used for

What they are used for, and with what

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Measuring principles at a glance

Electromagnetic flow meters, also called magmeters, use Faraday's law of induction: a conductive medium flowing through a magnetic field generates a voltage proportional to its velocity. They have no obstructions in the pipe and are the standard for water, wastewater and many aqueous media. Coriolis meters measure mass flow directly via the oscillation of flow tubes and also measure density. Ultrasonic meters evaluate the transit time difference of sound signals traveling with and against the flow. As clamp-on versions, they are mounted on the outside of the pipe without opening the line. Vortex meters count the vortices shed behind a bluff body and suit steam, gases and liquids. Variable area flow meters, or rotameters, display flow mechanically, often supplemented by limit contacts or an analog output. Calorimetric flow sensors mainly monitor whether a medium is flowing.

What matters when selecting an industrial flow meter

The most important question is the medium: is it conductive, gaseous, viscous or laden with solids? This determines the measuring principle, nominal diameter, pressure and temperature range and materials. Accuracy, turndown, required inlet and outlet runs and pressure loss also matter. Meters used for billing follow their own standards, such as ISO 4064 for water meters. ISO 9104 describes how the performance of electromagnetic meters is evaluated. Flow is output as pulses, analog signals or digitally via IO-Link, HART or fieldbus.

Flow sensors in practice

In solution examples, flow sensors measure the consumption of compressed air, water and coolant to allocate energy costs to individual machines and detect leaks. In the process industry, they control dosing and recipes; in cooling circuits, they monitor whether tools and lasers are adequately supplied. Endress+Hauser offers flow measuring devices for almost all measuring principles with digital interfaces for connection to IoT platforms. In the IoT stack, they sit on the source layer, and edge devices collect their values.

Frequently asked questions about industrial flow meters

How does a magnetic flow meter work?

A magnetic flow meter generates a magnetic field across the measuring tube. When a conductive medium flows through, Faraday's law induces a voltage that two electrodes pick up. It is proportional to the flow velocity and therefore to the volume flow. The tube has no obstructions and causes virtually no pressure loss. The medium needs a minimum conductivity, so gases, oils and demineralized water call for Coriolis, vortex or ultrasonic meters instead.

How does a Coriolis flow meter work?

A Coriolis flow meter sets one or two measuring tubes into oscillation. When medium flows through, Coriolis forces slightly twist the tubes, creating a phase shift between inlet and outlet. This shift is directly proportional to mass flow. The oscillation frequency also yields the density. Coriolis meters are very accurate and independent of conductivity and viscosity, for example in dosing and filling.

What is a clamp-on ultrasonic flow meter?

A clamp-on ultrasonic flow meter has sensors that are clamped onto the outside of the pipe. It measures the transit time difference of sound signals traveling with and against the flow and calculates the flow rate from it. The line does not need to be opened and the process does not need to stop. This makes it ideal for retrofits, temporary measurements and energy audits on existing plants.

What is a rotameter?

A rotameter is a variable area flow meter that indicates flow mechanically. In a vertical, tapered tube, the flow lifts a float whose height shows the flow rate, even without auxiliary power. It is used for gases and liquids in cooling, purging and dosing circuits. With limit contacts or a 4–20 mA output, its values can also be transferred to the controller and IoT platform.

What is a vortex flow meter used for?

A vortex flow meter is used for steam, gases and liquids with low viscosity. A bluff body in the pipe sheds vortices whose frequency is proportional to the flow velocity, and a sensor counts them. The meter has no moving parts, tolerates high temperatures and pressures and is a common choice for steam and compressed air measurement in energy monitoring.

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