What is a liquid flow meter?

A liquid flow meter is a kind of meter that measures the flow of liquid fluid in pipes or open channels. Liquid flow meters can effectively monitor liquid flow rates for water, fuels, chemicals and more fluids.

If you need to purchase a Liquid Flow Meter, this article will be your best Purchasing Guide. Keep reading, Please!

Flow meters are classified into liquid flow meters and gas flow meters according to the medium. Then the common liquid flow meters mainly include: vortex flowmeter, turbine flowmeter, electromagnetic flowmeter, ultrasonic flowmeter, differential pressure flowmeter, open channel flowmeter, Coriolis mass flowmeter, etc.

Sino-Inst offers a variety of  Liquid Flow Meters for flow measurement. If you have any questions, please contact our sales engineers.

Featured Liquid Flow Meters

Liquid Flow Meter Types

Turbine flow meter

Turbine flow meters are the main type of velocity flow meters. It uses a multi-blade rotor (turbine) to sense the average flow velocity of the fluid. A meter from which the flow or total volume is derived. Generally, it is composed of two parts: sensor and display instrument, and it can also be made into an integral type.

Application: Turbine flowmeter is widely used in measuring petroleum, organic liquid, inorganic liquid, liquefied gas, natural gas and cryogenic fluid.

Turbine flowmeter product features

  1. Strong resistance to impurities.
  2. Strong anti-electromagnetic interference and anti-vibration ability.
  3. Its structure and principle are simple and easy to maintain.
  4. Almost no pressure loss, saving power and electricity consumption.

Extended Reading: Liquid Turbine Flow Meter

Electromagnetic flow meter

Electromagnetic flowmeter is an instrument for measuring conductive liquid made according to Faraday’s law of electromagnetic induction.


The electromagnetic flowmeter has a series of excellent characteristics, which can solve the problems that other flowmeters are not easy to apply, such as the measurement of dirty flow and corrosion flow.

  • Electromagnetic flowmeters have a wide range of applications, and large-caliber meters are mostly used in water supply and drainage projects;
  • Small and medium calibers are often used in high-demand or difficult-to-measure occasions, such as the cooling water control of the blast furnace tuyere in the iron and steel industry, the measurement of pulp and black liquor in the paper industry, the strong corrosive liquid in the chemical industry, and the ore pulp in the non-ferrous metallurgical industry;
  • Small calibers and tiny calibers are often used in places with hygiene requirements such as the pharmaceutical industry, food industry, and biochemistry.

Electromagnetic flowmeter product features:

  1. Two-way measurement system.
  2. The straight pipe section required by the sensor is shorter, and the length is 5 times the pipe diameter.
  3. Low-pressure loss
  4. The measurement is not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity
  5. Mainly used in sewage treatment.

Vortex flow meter

The vortex flowmeter is a meter in which a non-streamlined vortex generator is placed in the fluid, and the fluid is alternately separated on both sides of the generator to release two series of regularly staggered vortices. When the flow cross-section is constant, the flow velocity is proportional to the volume flow. Therefore, the flow can be measured by measuring the oscillation frequency.

Application: The vortex flowmeter has developed rapidly and has become a general-purpose flowmeter.

Vortex Flowmeter Product Features

  1. The structure is simple, firm, no moving parts, high reliability, and reliable long-term operation.
  2. The installation is simple and the maintenance is very convenient.
  3. The detection sensor does not directly contact the measured medium, with stable performance and long life.
  4. The output is a pulse signal proportional to the flow rate, with no zero drift and high accuracy.
  5. The measurement range is wide, and the range ratio can reach 1:10.
  6. The pressure loss is small, the operating cost is low, and it is more energy-saving.

Extended reading: Threaded Vortex Nitrogen Gas Flow Meter

Mass flow meter

The principle of flow is directly related to the measurement; the indirect mass flowmeter is indirectly multiplied by the density meter and the volume flow to obtain the mass flow.

In the case of high temperature and high pressure in modern industrial production, the application of direct mass flowmeter encounters difficulties due to factors such as material and structure;
However, indirect mass flow meters are not suitable for practical applications due to their density being limited by the scope of application of humidity and pressure.

Mass flow meter product features:

  1. No mechanical transmission mechanism, small size, lightweight, easy to maintain
  2. High precision
  3. No moving parts inside, good stability
  4. Wide range ratio, much better than other traditional instruments

Read more about: Gas Thermal Mass Flow Meter

Ultrasonic flow meter

The ultrasonic flowmeter is designed based on the principle that the speed of ultrasonic propagation in the flowing medium is equal to the geometric sum of the average flow velocity of the measured medium and the speed of the sound wave itself. It also reflects the flow rate by measuring the flow rate. Ultrasonic flow meters can be divided into time difference type and Doppler type according to the measurement principle.


The propagation time method is applied to clean, single-phase liquids and gases. Typical applications include factory discharge liquid, strange liquid, liquefied natural gas, etc.;
Gas application has good experience in the field of high pressure natural gas;

The Doppler method is suitable for two-phase fluids with low heterogeneous content. Such as untreated sewage, factory effluent, and dirty process fluids, it is usually not suitable for very clean liquids.

Guess You’ll Like: Ultrasonic flow meters types & technical guide

Target flow meter

The target flow meter also called a drag force flowmeter. The target flow meter inserts a target (drag element) into the flow field. The target usually is a flat disc or a sphere with an extension rod. There will be a differential pressure. And then target flow meters measure the drag force on the inserted target and convert it to the flow rate. Sino-Inst manufactures target flow meters for liquid, gas, and steam measurement.


  1. The whole instrument has a solid structure and no moving parts, plug-in structure, easy to disassemble
  2. The dry calibration method can be used on the spot, that is, the weight hanging method is used.
  3. With integrated temperature and pressure compensation, directly output quality or standard
  4. The measuring range can be changed by replacing the baffle (target) according to actual needs
  5. Strong vibration resistance, pulsating flow can be measured within a certain range.

Differential pressure flow meter liquid flow metering

The differential pressure flowmeter is a meter that calculates the flow rate based on the differential pressure generated by the flow detection element installed in the pipeline, the known fluid conditions and the combined size of the detection element and the pipeline.

Application: Differential pressure flowmeter has a wide range of applications, and various objects have applications in the flow measurement of closed pipelines.
Such as fluid: single-phase, miscible, clean, dirty, viscous flow, etc.;
Work: normal pressure, high pressure, vacuum, normal temperature, high temperature, low temperature, etc.;
Pipe diameter: from a few millimeters to a few meters; flow: subsonic speed, sound speed, pulsating flow, etc.
Its consumption in various industrial sectors accounts for about 1/4 to 1/3 of all flow meters.

The most commonly used liquid differential pressure flowmeter is the orifice flowmeter.

Product features of orifice flowmeter:

  1. The structure of the throttling device is easy to replicate, simple, firm, stable and reliable in performance, long in service life and low in price.
  2. Wide application range, all single-phase flow can be measured, and part of mixed-phase flow can also be applied.
  3. The standard throttling device can be put into use without real flow calibration.
  4. The integrated orifice plate is simpler to install, no pressure pipe is needed, and it can be directly connected to a differential pressure transmitter and a pressure transmitter.

Oval gear flowmeter


  1. It relies on the pressure head of the measured medium to push the oval gear to rotate for measurement.
  2. The greater the viscosity of the medium, the smaller the leakage from the gear and the metering gap. Therefore, the larger the sticky skin of the nuclear test medium, the smaller the leakage error, and the more beneficial it is for measurement.
  3. It is suitable for the measurement of the flow of high-viscosity media, but not for fluids containing solid particles (solid particles will jam the gear so that the flow cannot be measured). If the measured liquid medium contains gas, it will also cause measurement errors.

Positive displacement flow meter

Positive displacement flow meter, also called fixed displacement flow meter, PD flow meter for short. It is the most accurate type among flow meters. It uses mechanical measuring elements to continuously divide the fluid into individual known volume parts. The total volume of fluid is measured according to the number of times that the measuring chamber is filled and discharged with this volume of fluid one after another.

Application: Positive displacement flow meters, differential pressure flow meters, and float flow meters are listed as the three most used flow meters. They are often used for total measurement of expensive media (oil, natural gas, etc.).

Float flow meter

Float flowmeter, also known as rotameter, is a kind of variable area flowmeter. In a vertical cone tube that expands from bottom to top, the gravity of the float of circular cross section is borne by the hydrodynamic force, so that the float can be Rise and fall freely in the cone.

Application: Float flowmeter is the most widely used type of flowmeter after differential pressure flowmeter, especially in small and micro flow.

Features of Rotameter:

  1. The most commonly used flow meter in industry and laboratories.
  2. The structure is simple, intuitive, low-pressure loss and convenient for maintenance.
  3. It must be installed on a vertical pipe section, and the fluid medium passes through the rotameter from bottom to top.

Extended reading: Liquid mass flow controller

You may like: Digital Flow Meters Guide| Liquid and Gas

Liquid Flow Meters Selection Guide

If from the upper part of this article, you do not know how to choose a suitable liquid flow meter. Then, you can follow our selection suggestions below.

Step 1: Confirm your liquid condition.

Before choosing a flow meter, you should sort out the details of your measured liquid.
such as:

  • Liquid name
  • Liquid temperature
  • Pipeline pressure
  • Liquid viscosity
  • Corrosive
  • Flow rate range
  • Pipe diameter

If you need to measure liquids under special circumstances, you can skip to the following:
Low temperature: Gear flow meter: High and low-temperature resistance (-196℃-200℃).
High viscosity: Oval Gear High Viscosity Flow Meter
Fuel: Industrial Fuel Flow Meters

Step 2: Identify your measurement needs.

The flow meter is designed to meet your measurement needs. Therefore, according to your needs, determine the function of the flowmeter. such as:

  • Measure volume flow or mass flow?
  • Is it necessary to display the instantaneous flow and cumulative flow locally?
  • What kind of signal output is needed? 4-20mA? Pulse?
  • What kind of installation form and size are planned? Such as ANSI150 flange? Outside clip?

Most liquid flow meters measure volumetric flow. If what you need is mass flow, you can jump to: Mass Flow Meters

If you are unwilling to change the pipeline, you can only choose to install the ultrasonic flowmeter with an external clamp.

Step 3: select the appropriate flow meter type.

Up to now, there may be many types of flow meters suitable for your measurement situation. Then you need to filter the flowmeter according to your pipe diameter and flow range.

For example, you need to measure the flow of milk. 2-inch pipe. Then you can refer to the flow range to select the appropriate flow meter.
2 inches, electromagnetic flowmeter, 2.21~35.35m³/h;
2 inches, turbine flowmeter, 4~40m3/h.

For example, what you need to measure is the water flow of a DN1000 pipeline. Then it is recommended that you choose the insertion electromagnetic flowmeter.

Step 4: Except for dedicated flow meters.

Under normal circumstances, when measuring some specific media, we will recommend a specific type of flowmeter.
such as:
Measure sewage, use an electromagnetic flowmeter.
To measure diesel oil, use a turbine flowmeter.

Step 5: Contact the manufacturer

The above liquid flow meter selection steps and selection suggestions are based on certain experiences.
If you are a newcomer, you are not sure about the above process. You can directly contact Sino-Inst sales engineers. We will provide you with the best advice.

Step 6: Combine the budget

According to your budget, choose the right liquid flow meter.
For example, you need to measure the water flow. Normally, you can choose an electromagnetic flowmeter or ultrasonic flowmeter. Then you can choose according to your budget.

Such as 2inch pipeline, DN50 electromagnetic flowmeter, USD 484.50/pc
With external clamp ultrasonic flowmeter, USD 423.00/pc

For example, 4inch pipe, DN50 electromagnetic flowmeter, USD 784.50/pc
With external clamp ultrasonic flowmeter, USD 423.00/pc

Of course, the above is our experience. It’s not absolute.

You may need the following traffic conversion tools to help you.

Extended reading: U-series Liquid Mass Flow Meter | Liquid-slurry flow measure

Liquid Flow Tools

Converters for conversion and calculation of flow. Or a calculation tool that requires flow measurement to obtain other measurement parameters. Help users choose the right flow sensor and transmitter!

DP Flow Meter Output CalculatorFlow Meter 4-20mA Current Output CalculatorFlow Velocity & Pipe Diameter to Volumetric Flow Rate Calculator
Mass Flow & Density to Volume Flow CalculatorMass Flow Rate Unit ConverterVolume Flow Rate Converter
Volume Flow & Density to Mass Flow CalculatorVolumetric Flow Rate & Pipe Diameter to Flow Speed Calculator

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How does a liquid flow meter work?

Liquid flow meter can be divided into the following categories according to the measurement principle:
Mechanics principles: instruments that fall into this category include differential pressure type and rotor type using Bernoulli’s theorem; impulse type and movable tube type using momentum theorem; direct mass type using Newton’s second law; using fluid momentum principle Target type; turbine type using the angular momentum theorem; vortex type and vortex type using the principle of fluid oscillation; pitot tube type using total static pressure difference, volume type, weir, trough type, etc.
Electrical principle: The instruments used for this kind of principle include electromagnetic, differential capacitive, inductive, strain resistance, etc.
Acoustic principle: There is an ultrasonic method for flow measurement using the acoustic principle. Acoustic (shock wave) etc. Thermal principle: There are calorimetric, direct calorimetry, indirect calorimetry, etc. that use the thermal principle to measure flow. Optical principle: laser type, photoelectric type, etc. are instruments of this type of principle. Principles of atomic physics: nuclear magnetic resonance, nuclear radiation, etc. are instruments that belong to this type of principle. Other principles: There are marking principles (tracing principles, nuclear magnetic resonance principles), related principles, etc.

What is a flow meter used for?

A meter that indicates the measured flow rate and/or the total amount of fluid in a selected time interval. Simply put, it is an instrument used to measure fluid flow in pipes or open channels.

Where should a flow meter be placed?

Most in-line flow meters are inline flow meters. They are all connected with the pipeline under test. Connect by flange, thread, etc.
The Insertion flowmeter is installed on the pipe under test by plug-in type. Suitable for larger pipe diameters.
Clamp-on flowmeter. The sensor is clamped outside the pipe for flow measurement.

Sino-Inst offers over 30 Liquid Flow Meters products. About 50% of these are differential pressure flow meters. 40% are water meters (like the Insertion Turbine Flow Meter), and 40% are water treatment (like the Annubar flow meter ).

A wide variety of Liquid Flow Meters options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Liquid Flow Meters, located in China.

The top supplying country is China (Mainland), which supply 100% of the Liquid Flow Meters respectively.

Sino-Inst sells through a mature distribution network that reaches all 50 states and 30 countries worldwide. Liquid Flow Meters products are most popular in Domestic Market, Southeast Asia, and Mid East.

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