A flow meter, also called flow sensor, is a device or an instrument used to measure linear, nonlinear, mass or volumetric flow rate of a liquid or a gas.

In short, it is a meter used to measure the flow of fluid in a pipe or open channel.

Flow meters are referred to by many names,

such as flow gauge, flow indicator, liquid meter, flow rate sensor, etc.

depending on the particular industry.

You may have heard of vortex flowmeters, ultrasonic flowmeters, electromagnetic flow meters,

turbine flowters, coriolis mass flowmeters.

Here, let’s take a closer look at what is a flow meter.

What is a Flow Meter?

You may like the wikipedia: Flow Measurement.

If you need to know the flow rate in you pipe, or river, that when you need a flow meter. So, flow meter is the instrument that can finish the flow measurement.

Flowmeters consist of a primary device, transducer and transmitter.

The transducer senses the fluid that passes through the primary device.

The transmitter produces a usable flow signal from the raw transducer signal.

These components are often combined, so the actual flowmeter may be one or more physical devices.

Different types of flow meters are available for different application,

and depending upon the requirement, a careful selection of flow meter is made.

For e.g., we prefer vortex flow meters flow steam flow measuremnet. And we like the ultrasonic flow meters for non-contact pipe flow measuremnt.

Turbine type flow meter cannot be used for measuring the flow in an unclear liquid

(waste water or corrosive liquids).

How does a flow meter work?

Flowmeters are devices that measure the rate of liquid, gas or vapor that passes through them.

Some flowmeters measure flow as the amount of fluid passing through the flowmeter during a time period (such as 100 liters per minute).

Other flowmeters measure the totalized amount of fluid that has passed through the flowmeter (such as 100 liters).

Flow measurement can be described by :
Q = A x v

Q is flow rate, A is the crosssectional area of the pipe, and v is the average fluid velocity in the pipe.

Putting this equation into action, the flow of a fluid traveling at an average velocity of a 1 meter per second,

through a pipe with a 1 square meter cross-sectional area is 1 cubic meter per second.

Note that Q is a volume per unit time, so Q is commonly denoted as the “volumetric” flow rate.

Now consider the following equation:
W = rho x Q

Where W is flow rate (again – read on), and rho is the fluid density.

Putting this equation into action, the flow rate will be 1 kilogram per second,

when 1 cubic meter per second of a fluid with a density of 1 kilogram per cubic meter is flowing.

(The same can be done for the commonly-used “pounds”. Without getting into details — a pound is assumed to be a mass unit.)

Note that W is a mass per unit time, so W is commonly denoted as the “mass” flow rate.

Now — which flow do you want to measure? Not sure? In some applications, measuring the volumetric flow is the thing to do.

Consider filling a tank.

Volumetric flow may be of interest to avoid overflowing a tank,

where liquids of differing densities can be added.

(Then again, a level transmitter and high level switch/shutoff may obviate the need for a flowmeter.)

Consider controlling fluid flow into a process that can only accept a limited volume per unit time.

Volumetric flow measurement would seem applicable.

In other processes, mass flow is important.

Consider chemical reactions,where it is desirable to react substances A, B and C.

Of interest is the number of molecules present (its mass), not its volume.

Similarly, when buying and selling products (custody transfer) the mass is important, not its volume.

You may like: Industrial flow meters

Types of flow meter

What are the types of flow meter? You may always hear words like: electromagnetic, vortex shedding, Coriolis, Ultrasonic, Venturi…. If you want to make better choice for your flow measurement, you may need to know more about the flow meter types. Flowmeters are used to measure the flow in a piping system. Let us see the types of flow meters by their different working principle.

Flow Metering Principles

From the measurement principle, the flowmeter can be divided into Volumetric flowmeters and Mass flwo meters.


  • Differential Head type
    • Orifice plates
    • Venturi meters
    • Annubar
  • Differential Area type (Rotameters)
  • Electromagnetic flowmeters
  • Ultrasonic flowmeters
  • Turbine flowmeters
  • Vortex flowmeters
  • Positive Displacement Meters


  • Coriolis Mass flowmeter
  • Thermal Mass flowmeters

For different working principle, We offer different types of flow meters, like:

Where are flow meters used?

Where are flow meters used? Or, What does a flow meter measure?

At industrial sites, meters that measure fluid flow are referred to as flow meters or flow sensors.

It is one of the most important instruments in industrial measurement.

With the development of industry, the accuracy and range of flow measurement requirements are getting higher and higher.

In order to adapt to various purposes, various types of flowmeters have been successively launched,

widely used in oil and gas, petrochemical, water treatment, food and beverage.

Industries such as pharmaceuticals, energy, metallurgy, pulp and paper, and building materials.

  1. Measurement of gas mass flow in industrial pipelines
  2. Smoke flow rate measurement from the chimney
  3. Calciner flue gas flow measurement
  4. Air flow measurement during gas process
  5. Compressed air flow measurement
  6. Gas flow measurement during semiconductor chip manufacturing process
  7. Gas flow measurement in sewage treatment
  8. Gas flow measurement in heating ventilation and air conditioning systems
  9. Flux recovery system gas flow measurement
  10. Measurement of combustion gas flow in a combustion boiler
  11. Gas flow measurement of natural gas, flare gas, hydrogen, etc.
  12. Measurement of carbon dioxide gas flow during beer production
  13. Measurement of gas mass flow in the production process of cement, cigarette and glass factory
  14. Open channel

What type of flow meter is right for you?

There are no “universal” flow meters which are suitable for all applications.

Selecting the proper technology for your application requires,

writing a flow specification which covers the use of the meter.

There are usually trade-offs with each meter type, so knowing the critical specifications will be important.

There are some question that need to be answered before choosing a Flow Sensor.

  1. What is the fluid being measured?
  2. Do you require rate measurement and/or totalization?
  3. If the liquid is not water, what viscosity is the liquid?
  4. Do you require a local display on the flow meter or do you need an electronic signal output?
  5. What is the minimum and maximum flowrate?
  6. What is the minimum and maximum process pressure?
  7. What is the minimum and maximum process temperature?
  8. Is the fluid chemically compatible with the flowmeter wetted parts?
  9. If this is a process application, what is the size of the pipe??

Which flowmeter do you need? Choose your flowmeters below

All flow meters can work with the AMS TREX, HERE !

You may like:

Sino-Inst offer over 20 flow meters, with Best Price.

A wide variety of flow meters options are available to you, such as free samples, paid samples.

About 13% of these are magnetic flow meter, 14% are Insertion Magnetic Flow Meter, 25% are Venturi flow meter,

13% are Handheld ultrasonic flow meter, and others are Liquid Turbine Flow Meters.

Sino-Inst is wastewater flow meter suppliers, located in China.

Wastewater flow meter products are most popular in North America, Mid East, and Eastern Europe.

The United States, and India, which export 99%, 1%, and 1% of ultrasonic level transmitter respectively.

You can ensure product safety by selecting from a certified supplier, with ISO9001, ISO14001 certification.

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Please provide your measurement parameters or details. Sino-Instrument support customer customization and OEM

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