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Engineering Essentials: Flow Meters and Flow Switches

Flow Meters and Flow Switches

Flow meters are devices that system operators use to measure the volume and the flow rate of liquids or gases. They work in various applications depending on the amount of flow, the temperature condition, and the substance’s type to be measured.

The two main categories of flow meters are;

i) The mass flow meter

A device that measures the flow rate, mass, and volume of a liquid or fluid moving in a tube or pipe. The temperature and pressure of the fluid change the density and viscosity of the flow. 

Types of mass flowmeters

a) The impeller-turbine mass flow meters

This device measures the mass flow rate using the turbine and impeller. The turbine is located down the impeller enabling it to remove the momentum of the fluid, thus recording the mass reading of the liquid.

b) The Coriolis mass flow meters

This type of mass flow meter uses the Coriolis forces to notice the change in the oscillations flow of a fluid in a tube by using electromagnets that are always strong.

c) The turbine-twin mass flow meters

The turbine-twin mass flow meter contains two turbines that rotate at different angles and use strong magnets to record the mass flow rate of the fluid.

d) Thermal mass flowmeters

The flow rate mass of a heated liquid or fluid is determined by the thermal mass flow meter. The metering device detects the definite group of the substance immediately after the substance molecules get into contact with heat.

ii) Volumetric flowmeters

Are flow devices that measure the volume of a liquid or any substance in a tube at a particular time, either directly or indirectly.

Types of volumetric flowmeters

a) Magnetic meters

These are flow meters that system operators use to measure the flow of acids, slurries, and water. The pipe senses the voltage by the magnetic ions of the fluids in the tube.

b) Vortex meters

Vortex meters always measure the flow of clean water, wastewater, and steam by interpreting the velocity of the liquid flowing inside the water pipe.

c) Turbine meters

Turbine flow meters measure the flow rate of moving water pipes using the operator’s kinetic energy and enhance the increase in pulses, which leads to increased velocity of the fluid.

d) Ultrasonic meters

Ultrasonic meters usually measure the velocity of the liquid traveling in a pipe. They are primarily applied in aerated and dirty fluids to measure the sound waves of the contaminated liquids.

On the other hand, a flow switch is a device that detects, monitors, and records the flow rate of liquids, gases, or steam. The main difference between flow meters and flow switches is that the flow switch can detect, control, and alert the user on the liquid flow while the flow meter regulates the flow rates, and the operator has to check and record the measurements.

Types of flow switch

a) Volumetric flow switches

Volumetric flow switches are switches that measure the flow rate of gases and liquids in volume per cubic feet in each minute.

b) Gas flow switches

Gas flow switches measure the flow rate of steam and air. System operators mainly use it in HVAC applications.

c) Velocity flow switches

Engineers use this type of flow switch in measuring the flow rate of a substance traveling in a specific media. It continuously records its measurements in velocity feet in each minute.

d) Liquid flow switches

Most engineering industries use these switches to measure the flow rate of chemicals, slurries, water, and lubricants.

Applications of flow switch

i) Used in pipelines to ensure the continuous media flow of water.

ii) Engineers use flow switches in HVAC systems at the commercial and significant buildings.

iii) Flow switches help in keeping the tank at certain designated levels.

iv) Flow switches help in detecting the blockage in a pump and alerting the user on the issue.

v) Flow switches are suitable for noticing valve failures and staging the fluid or water pump.

Factors to consider when choosing a flow switch to use

i) The pipe diameter to ensure that the flow switch can securely fit and provide the correct measurements.

ii) One should also consider the type of media the flow switch measures to avoid any corrosion or rusting of the pipe.

iii) Considering the temperature range helps in knowing the maximum level of temperature the flow switch can withstand when monitoring the flow rate.

iv) The material of the flow switch should consider the maximum pressure of the liquid flow at a specific media.


Flow meters and flow switches are essential devices to many industries. They help engineers in performing different functions under various applications. Choosing the proper flow meter or flow switch helps in the excellent performance of other activities.

About the Guest Author

Naman Modi is a Professional Blogger, SEO Expert & Guest blogger at, He is an Award-Winning Freelancer & Web Entrepreneur helping new entrepreneur’s launches their first successful online business.

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