Measurement and Control Equipment

Flow Meters: Types of Industrial Flow Meters and How to Choose

Compare the principles, suitable fluids and selection criteria of electromagnetic, turbine, variable area, ultrasonic, Coriolis and vortex flow meters.

ORFA Technical TeamUpdated: Oct 30, 20263 min read

In industrial plants, accurate measurement of liquid, gas and steam flow is a basic requirement for process control, energy management, cost tracking and product quality. Flow meters measure the velocity or quantity of the fluid passing through a pipeline and make this data available for display, control systems or billing.

There is no single “best” flow meter for every fluid and application. This article summarises the common flow meter types, the fluids they suit and the criteria for selecting the right one.

What Is a Flow Meter?

A flow meter measures the volumetric flow rate (e.g. m³/h), mass flow rate (e.g. kg/h) or totalised quantity of a fluid in a pipe or channel. The result can be shown on a local display or transmitted to PLC/SCADA systems via 4-20 mA, pulse or Modbus outputs.

Types of Flow Meters

Type	Measuring principle	Typical fluid
Electromagnetic flow meter	Faraday’s law of induction; a conductive liquid moving through a magnetic field generates a voltage proportional to velocity.	Water, wastewater, slurries, chemicals, food liquids (electrically conductive liquids only)
Turbine flow meter	The speed of a turbine rotated by the flow is proportional to flow rate.	Clean, low-viscosity liquids and gases
Variable area (float) flow meter	The height of a float in a tapered tube indicates the flow.	Local indication for liquids and gases
Ultrasonic flow meter	Difference in transit time of sound waves with and against the flow.	Clean liquids; clamp-on models measure without cutting the pipe
Mass (Coriolis) flow meter	Coriolis force generated by the flow in vibrating tubes; measures mass flow directly.	Liquids and gases, high-accuracy filling and dosing
Vortex flow meter / steam meter	Frequency of vortices shed behind a bluff body in the flow.	Steam, gases and clean liquids
Water meter	Mechanical (vane/Woltman) or electronic measurement.	Mains and process water consumption

Heat meters (calorimeters), formed by combining a flow meter with a pair of temperature sensors and a calculator, measure the thermal energy carried by the fluid.

Benefits of Flow Measurement

Process control: Accurate flow data keeps mixing ratios and process parameters under control.
Energy and cost tracking: Measuring water, steam and energy consumption helps to detect losses and inefficiencies.
Product quality: Repeatable results in dosing and filling.
Safety and protection: Loss of flow or unexpected increases are noticed early and equipment is protected.

Flow Meter Selection Criteria

Fluid properties: Liquid, gas or steam; conductivity, viscosity, temperature, pressure, solids and corrosiveness. For example, an electromagnetic flow meter cannot measure non-conductive oils and hydrocarbons.
Flow range: Minimum and maximum flow must fall within the meter’s range (turndown).
Required accuracy: Billing, process control and simple monitoring need different accuracy.
Installation conditions: Pipe size and material, and the straight pipe runs required upstream and downstream.
Output and communication: Analogue, pulse or digital communication needs.
Pressure loss and maintenance: Designs without moving parts offer low pressure loss and little maintenance.
Total cost: Installation, calibration and operating costs as well as purchase price.

Tip: Size the flow meter for the actual flow range, not the pipe size. An oversized meter loses accuracy at low flow velocities.

Frequently Asked Questions

Can an electromagnetic flow meter measure steam?

No. Electromagnetic flow meters only measure electrically conductive liquids. Steam is usually measured with vortex meters or differential pressure meters designed for steam.

What is the difference between a flow meter and a flow switch?

A flow meter measures the value of the flow rate; a flow switch only detects whether flow is above or below a set point and changes a contact.

Which flow meter is best for clean water?

Electromagnetic, turbine and ultrasonic meters all work well with clean water; the choice depends on accuracy, pipe size, budget and whether the pipe can be opened for installation.

Conclusion

The right flow meter is chosen by evaluating fluid properties, flow range, accuracy and installation conditions together. ORFA supports your flow measurement needs with electromagnetic, turbine and variable area flow meters and water meters. Explore the range on our Flow Measurement Equipment page.

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