Bobby Brown
Post 2019-09-09
Flowmeter Selection Guide - The Pros and Cons of 11 Types of Flowmeters


  • From purchasing to installation, this article guides you step by step on how to choose a flowmeter based on your needs.
  • A ten-minute read to understand 11 types of flowmeters: ultrasonic, paddle wheel, area, Coriolis, volumetric, vortex, turbine, differential pressure, laminar flow, electromagnetic, and thermal mass flowmeters.


Flowmeters are crucial in modern fluid handling, but choosing the right one can be challenging. This article explores different types of flowmeters and their applications, highlighting their importance. We discuss accuracy, installation, and considerations for different fluid types to help you make an informed choice. Understanding the advantages and disadvantages of various flowmeters ensures the efficient operation of fluid handling systems. Whatever your requirements, this guide offers valuable information. Continue reading to learn how to select the best flowmeter for your needs.

How to Choose the Right Flowmeter: What Aspects to Consider?

1. Accuracy and Repeatability

Flowmeters are widely used in industrial automation systems. Accuracy and repeatability are key performance indicators for measuring flowmeters, crucial for system stability and product quality. Repeatability refers to the ability of a measurement instrument to consistently display the same flow indication under the same conditions, meaning measurements need to be made at the same temperature, pressure, flow rate, and other environmental conditions to ensure system repeatability and reliability. Reproducibility involves variations in measurement across different flow conditions, flowmeters, operators, and over longer periods, possibly due to instrument drift, wear, environmental changes, or operator skill differences. Calibration and regular maintenance are essential for long-term accuracy and reliability of flowmeters. In summary, flowmeters are indispensable in modern industrial automation systems. Their performance evaluation and calibration are key to ensuring system stability and product quality.

2. Selection Considerations

Key Reference Elements
Fluid Type: Determine if the fluid to be measured is liquid, gas, or steam, as different fluid types are suitable for different flowmeters.
Fluid Characteristics: Consider the fluid's viscosity, conductivity, chemical activity, temperature range, and presence of solid particles, or if the liquid is corrosive, to help select the material of the flowmeter body, float, O-rings, etc.
Measurement Range: Define the required flow range, including minimum and maximum flow values, such as 1.010LPM, 100600LPM, 70-700NLPM.
Pipe Diameter or Fitting Specifications: The flowmeter's size and model need to match the measuring pipeline's diameter or fitting specifications to ensure accurate measurement and avoid installation incompatibility issues. For example, when purchasing an area flowmeter, knowing the size and specification of the fitting, such as 1/2" male thread, 3/4" American standard socket, etc., is necessary to meet installation conditions.
Other Reference Elements
➤ Installation Environment: Consider the physical space, environmental conditions (e.g., humidity, temperature, pressure) where the flowmeter will be installed, and if there are flammable, explosive, or corrosive environments.
➤ Accuracy Requirements: Choose a flowmeter based on the accuracy requirements of the application. Different flowmeters vary in accuracy, so determine the accuracy level needed for your application.
➤ Economy: Consider the purchase cost as well as maintenance and operational costs. Some flowmeters may have a lower initial cost but higher long-term operational and maintenance costs.
➤ Output Signal Requirements: When purchasing an electronic flowmeter, confirm the system's output signal requirements, such as analog signal, pulse output, digital communication (e.g., HART, Profibus, Modbus).
➤ Maintenance and Operation Simplicity: Choose flowmeters that are easy to install, calibrate, and maintain to reduce operational interruptions and maintenance costs.
➤ Certifications and Standards: Depending on specific application requirements, you may need to choose flowmeters that comply with specific industry standards or certifications (e.g., sanitary standards for the food and beverage industry, explosion protection).

Considering these elements will help you select the most suitable flowmeter for your specific needs.

3. Installation Location

When installing a flowmeter, consider the following key points:

( 1 ) Horizontal or Vertical Installation:

Horizontal pipelines
In horizontal pipelines, if the pressure is insufficient to fill the pipe with liquid, a partial pipe situation may occur, leading to inaccurate flow measurement. In such cases, consider installing the flowmeter in the depression of a U-shaped pipe to ensure the pipe is filled with liquid, thus obtaining accurate measurement results.
Vertical pipelines
For vertical pipe installation, it is recommended to install the flowmeter on vertical pipelines where liquid flows upwards. For pipelines where liquid flows downwards, the flow is unstable due to segmented droplet flow, resulting in inaccurate flow data. Conversely, for upward flowing liquid, the flow is more stable due to gravity, and air bubbles will gather at the top of the pipe, allowing for more accurate measurements.
( 1 )Need for Piping: Assess if piping work is needed for the flowmeter, considering installation, maintenance, and if the production line tolerates downtime. Some flowmeters might necessitate pipeline cutting, being more cost-effective, while non-cutting installations could be pricier. Ensure chosen flowmeter matches existing piping for best results.
( 2 )Pressure Loss: Note the pressure loss when installing a flowmeter, as it introduces resistance to fluid motion. Pressure loss varies with the flowmeter's model, pipe diameter, fluid properties, and installation method. Optimal flowmeter design can minimize pressure loss, enhancing fluid efficiency.
( 3 )Weight: The flowmeter's weight could strain the pipeline, risking deformation or leaks. Select a flowmeter whose weight the pipeline can support to avoid installation damage.
( 4 )Pipe Diameter: Flowmeters vary in pipe diameter limits, impacting fluid flow rate and pressure. A too-small pipe diameter could hasten flow, risking pump failure and inaccurate measurements. Conversely, a too-large diameter slows flow, also inaccurately. Choose a flowmeter with a diameter that suits the pipeline and fluid for precise, reliable measurements.

When installing a flowmeter, we need to consider the horizontal or vertical installation position, the need for piping, pressure loss, weight, and pipe diameter. These factors directly affect the flowmeter's measurement accuracy and applicability.

Suitable Flowmeters for Different Fluid Types

1. What are the Types of Fluids? How to Differentiate?

Types of Fluids

Fluids are a common form of matter in our lives, including gases and liquids. Understanding the types of fluids and how to differentiate them is crucial in various fields, such as engineering, science, and everyday applications. Below, we explore the types of fluids and how to differentiate them.

Types of Fluids:

  • Gases: Gases are substances without a fixed shape or volume, with relatively large distances between molecules and high-speed, random motion. Gases are compressible and have a lower density, common examples include oxygen, nitrogen, carbon dioxide, etc.
  • Liquids: Liquids have a fixed volume but no fixed shape, with molecules closer together than gases and moving at a relatively slower speed. Liquids have a fixed density and are less compressible, common examples include water, oil, alcohol, etc.

Ways to Differentiate Fluids:

  • Viscosity: Viscosity measures the internal resistance of a fluid, reflecting its ability to resist flow. Fluids with high viscosity have greater internal friction and flow more slowly, common examples include resin or thick oil. Viscosity can be determined by measuring the flow rate and stress of a fluid between two parallel plates.
  • Density: Density is the measure of mass per unit volume of a fluid, reflecting the closeness of fluid molecules. Fluids with high density have a greater mass, common examples include metals or dense starch solutions. Density can be determined by measuring the mass and volume of a fluid.
  • Pressure: Pressure is the force exerted by a fluid on the walls of its container, depending on the mass of the fluid and its height. Changes in pressure can affect the flow properties and speed of a fluid. Pressure can be measured using instruments such as pressure gauges or pressure transmitters.
  • Flow Rate: Flow rate is the volume or mass of fluid passing through a specific area in a unit of time. It describes the motion speed and flow properties of a fluid. Methods to measure flow rate include using flowmeters or measuring the time and volume of fluid passing through a specific area.

Through these methods, we can differentiate and characterize fluids. Measuring physical quantities such as viscosity, density, pressure, and flow rate helps us understand and control fluid behavior, applying it in various fields, such as industrial process control, environmental monitoring, and fluid mechanics research. However, it's important to note that fluid properties are not limited to the physical quantities mentioned above but also include temperature, chemical composition, and flow characteristics. Therefore, when differentiating and characterizing fluids, consider multiple factors and choose appropriate measurement methods and tools.

2. Which Flowmeters are Suitable for Measuring Liquids? What to Consider?

Flowmeters play a key role in industrial and scientific fields, accurately measuring fluid flow and providing important process control and monitoring data. When selecting flowmeters suitable for measuring liquids, consider the following points:

  • Differential Pressure Flowmeter: Differential pressure flowmeters calculate flow by measuring the pressure difference across the meter. They are suitable for measuring low-viscosity liquids and gases. This type of flowmeter has the advantage of relatively low cost and good accuracy in some applications.
  • Electromagnetic Flowmeter: Electromagnetic flowmeters calculate flow by measuring the velocity of a liquid in a magnetic field. They are suitable for liquids with good conductivity, such as water and solutions. This type of flowmeter has good accuracy and stability and does not cause pressure loss to the fluid.
  • Ultrasonic Flowmeter: Ultrasonic flowmeters calculate flow by measuring the velocity of ultrasonic waves in a liquid. They are suitable for high-viscosity liquids and liquids with solid particles. This type of flowmeter does not contact the fluid and does not contaminate or cause pressure loss to the fluid.
  • Thermal Mass Flowmeter: Thermal mass flowmeters calculate flow by measuring the average temperature of a liquid in a pipeline. They are suitable for low-viscosity liquids, such as gases and clean liquids. The principle of this type of flowmeter is based on heat conduction, and the effect of ambient temperature on measurement results must be considered.

Keys Considerations for Choosing Liquid Flowmeters:

  • Flow Rate Range: Different flowmeters have different flow rate ranges. Choose a flowmeter that covers the required flow rate range based on actual application needs.
  • Viscosity: For high-viscosity fluids, such as paste-like materials or high-viscosity liquids, choose a suitable flowmeter. Ultrasonic flowmeters perform well in this aspect, capable of measuring the flow of high-viscosity liquids.
  • Measurement Accuracy: Different flowmeters have different measurement accuracies. Choose a flowmeter with the required accuracy level based on application requirements and accuracy standards.
  • Environmental Temperature: Thermal flowmeters are sensitive to environmental temperature. When choosing a flowmeter, consider the effect of environmental temperature on measurement results to ensure accuracy and stability.

When selecting flowmeters for liquids, consider flow rate, viscosity, accuracy, and temperature. Choose the type—differential pressure, electromagnetic, ultrasonic, or thermal—based on liquid properties for accurate measurement.

3. Which Flowmeters are Suitable for Measuring Gases? What to Consider?

Gas flow measurement plays an important role in many industrial fields. Choosing the right flowmeter technology is crucial for accurate gas flow measurement. Among various technologies, including thermal mass flowmeters, differential pressure flowmeters, ultrasonic flowmeters, Coriolis mass flowmeters, and mechanical flowmeters, each has its unique principle and applicability.

  • Thermal Mass Flowmeter: Calculates flow by measuring the heat change generated by gas passing through the instrument. It is suitable for low flow rates and non-corrosive gases but is sensitive to changes in gas temperature.
  • Differential Pressure Flowmeter: Calculates flow by measuring the pressure difference generated by gas passing through the instrument. Based on Bernoulli's principle, when gas passes through a narrow channel, flow speed increases, and pressure drops. Differential pressure flowmeters are suitable for various gases and medium flow rates.
  • Ultrasonic Flowmeter: Utilizes transmitted and received ultrasonic signals to measure gas flow speed, calculating flow based on changes in sound wave propagation time. Ultrasonic flowmeters are suitable for a wide range of gas types and large flow rates, with no impact on the fluid.
  • Coriolis Mass Flowmeter: Calculates mass flow by measuring the Coriolis force generated by gas passing through the instrument. It uses the Coriolis effect in a bending pipeline to measure fluid mass. Coriolis mass flowmeters are insensitive to changes in gas density, suitable for high-precision mass flow measurements.

Keys to Consider When Choosing Gas Flowmeters:

  • Properties of Gas: Gas properties like density, viscosity, and compressibility significantly impact flowmeter selection. Identifying these properties is essential for choosing the right flowmeter technology, ensuring accurate gas measurements.
  • Gas Pressure: Gas pressure impacts flowmeter selection; different meters suit high or low-pressure gases. Choose a flowmeter that accurately measures within your gas's pressure range.
  • Gas Temperature: Temperature influences flowmeter performance. Select a flowmeter adaptable to your gas's temperature variations for consistent results.
  • Flow Rate Range: Identify your gas's flow rate needs. Different flowmeters cover various ranges. Select one that matches your required flow rate for accurate measurements.
  • Application Requirements: Consider your application's accuracy needs for gas flow measurement. Select a flowmeter that meets these demands to ensure precise results.

Selecting the right flowmeter technology tailored to specific application requirements is crucial for precise gas flow measurement. Consulting with flowmeter experts or engineers is advised for informed guidance and support. This careful selection process guarantees measurement reliability and accuracy, vital for both industrial control and scientific research.

Insights from the Experts - Choose the Right Flowmeters :

1. Ultrasonic Flowmeter

Ultrasonic flowmeters measure fluid velocity using ultrasonic signals to calculate volumetric flow through pipes, suitable for both clean and dirty liquids.

Ultrasonic Flowmeter


  • Unobstructed flow path ensures fluid flows without blockage, reducing measurement interference and enhancing accuracy.
  • Lack of moving parts eliminates the need for lubrication and maintenance, reducing failure risks and maintenance costs.
  • No additional pressure loss during installation in the fluid system, ensuring energy-efficient performance.
  • Suitable for chemically corrosive liquids, providing a safe and reliable measurement solution.
  • Measurement variables have a linear relationship with flow velocity, making results more reliable and accurate.
  • Low maintenance costs due to minimal calibration and adjustment requirements, saving time and costs.
  • Capable of measuring in both forward and reverse flow, offering greater flexibility and application range.
  • Transit-time flowmeters are unaffected by temperature, density, and concentration changes, ensuring stable measurements.
  • Can be retrofitted on existing pipelines but require onsite calibration for accuracy.


  • Still faces challenges in measuring liquids and gases, necessitating further improvement and research.
  • Sound beams must traverse a representative cross-section, influenced by the fluid's cross-sectional area, requiring sufficient inlet and outlet lengths during installation for even fluid flow.
  • Errors may occur with sediment, necessitating regular cleaning and maintenance for accurate and reliable measurements.
  • Transit-time flowmeters require clean liquids to avoid contamination affecting measurement results.
  • Doppler flowmeters are only accurate for mildly contaminated fluids or those with minimal bubbles.
  • Doppler measurements are affected by changes in sound speed due to temperature, density, and concentration variations, requiring consideration and compensation in applications.
  • Not suitable for severely contaminated liquids, which may cause measurement inaccuracies.
  • Bubbles can cause measurement errors, especially in liquids with a high bubble content.

When selecting an ultrasonic flowmeter, consider the following factors:

  • Medium Type: Water is simpler and more economical to measure, solids or gases are more complex.
  • Temperature Range: Normal ranges are easier to manage; extreme temperatures require advanced equipment.
  • Pipe Material: Stainless steel, copper, and carbon steel are easier to install; lined or thick-walled pipes are more challenging.
  • Pipe Size: Wide applicability, but the pipe must be full of the medium.
  • Installation Space: Longer pipeline paths are easier for installation; shorter pipes may require high-end flowmeters.
  • Required Accuracy: For flow verification, choose basic models; for billing or batch control, opt for high precision.
  • Output Signal: Select analog or digital output based on needs.
  • Fluid Characteristics: Consider the fluid’s viscosity, density, and other impacting factors.
  • Ultrasonic flowmeters come in two main types: Doppler and transit-time. Doppler is suited for fluids with suspended particles or bubbles, while transit-time is ideal for clean liquids like water and oil.
Ultrasonic flowmeters come in two main types: Doppler and transit-time. Doppler is suited for fluids with suspended particles or bubbles, while transit-time is ideal for clean liquids like water and oil.

Selecting an ultrasonic flowmeter requires careful consideration of the medium type, temperature range, pipe material and size, and accuracy requirements. Proper selection ensures reliability and precision in measurements, as well as long-term durability and low maintenance costs of the equipment. [1][2]

2. Paddle Wheel Flowmeter

Paddle Wheel Flowmeter: Also known as impeller meters, they utilize fluid dynamics to spin the paddle, with speed proportional to flow, ideal for low-viscosity liquids.

Paddle Wheel Flowmeters


  • Excellent reproducibility and responsiveness: Offers stable flow measurement results and quick response to fluid changes.
  • Simple structure and low cost: Comprised of a rotating paddle wheel and a sensor, making it economically priced due to its simple design.
  • Compact size for high-capacity measurements: Its small size facilitates measurement in limited spaces and accurately measures large fluid volumes.


  • Lower accuracy than other flowmeters: Affected by various factors like fluid viscosity and flow distribution, making it unsuitable for high-accuracy applications.
  • Not suitable for low flow rates: Requires sufficient fluid flow for stable paddle wheel rotation, with low flow rates potentially affecting measurement precision.
  • Not suitable for high-viscosity fluids: High-viscosity fluids can hinder paddle wheel rotation, impacting measurement accuracy.

When considering a paddle wheel flowmeter, factor in:

  • Application requirements: Determine accuracy levels and flow ranges to see if a paddle wheel flowmeter meets your needs.
  • Fluid properties: Understand the viscosity and flow distribution of the fluid to assess the performance of the paddle wheel flowmeter under these conditions.
  • Budget constraints: Its relatively lower price makes it an ideal choice for applications with limited budgets.
  • Installation requirements: Consider the size and installation needs to ensure compatibility with the existing piping system.

Paddle wheel flowmeters offer practicality and cost-effectiveness in many applications. Despite their lower accuracy and limitations with low flow rates and high-viscosity fluids, they remain a reliable and economical choice within their capabilities. Choosing the most suitable flowmeter based on specific application needs and fluid characteristics ensures accurate flow measurement and reliable operation.

3. Rotameter (Variable Area Flowmeter)

Rotameter measures flow by the vertical movement of a float in a tapered tube, with some models featuring guide rails to limit the float's movement for more precise measurements, typically suited for small flow rates.

Rotameter (Variable Area Flowmeter)


  • Reasonably priced with a simple structure: Rotameters are an economical choice due to their straightforward design.
  • No need for auxiliary power: They operate on fluid pressure differences, reducing energy consumption.
  • Suitable for both liquids and gases: Rotameters can measure various fluids, offering a wide range of applications.
  • No inlet or outlet straight sections required: Unlike some meters, rotameters don't need extra straight sections, simplifying installation in confined spaces.
  • Easy assembly and maintenance: Generally composed of few parts, they are straightforward to operate and maintain.


  • Not suitable for high-viscosity fluids: Their accuracy and reliability can be compromised by the viscosity of the fluid.
  • Limited for low flow rates: Their precision can be affected at low flow rates due to smaller changes in the measurement area.

When selecting a rotameter, continue to consider:

  • Fluid properties: Most liquids and gases are suitable, but high-viscosity fluids may not be ideal. Ensure the model matches the specific properties of the fluid being measured.
  • Flow range: Their measurement range is limited. Larger flow ranges could lead to inaccuracies. Ensure the selected meter's range meets the application requirements.
  • Measurement accuracy: Compared to other high-precision meters, rotameters have relatively lower accuracy. High-precision applications might require different types of flowmeters.
  • Installation requirements: Their flexibility in installation is enhanced by not requiring inlet or outlet straight sections. Still, ensure to meet installation standards to avoid vortices, interference, and pressure loss.
  • Maintenance and calibration: Rotameters generally have low maintenance needs, but regular calibration is key to accurate measurements. Ensure timely calibration and maintenance to maintain accuracy and reliability.

Rotameters offer significant advantages such as cost-effectiveness, simplicity, and versatility across fluids. However, they also have limitations, like restrictions on high-viscosity fluids and low flow rates. When choosing a rotameter, carefully consider the fluid properties, flow range, accuracy needs, and installation and maintenance requirements to ensure the selected meter suits the actual application needs.

4. Coriolis Mass Flowmeter

Coriolis Mass Flowmeter: Also known as Coriolis meters, they determine mass flow by measuring oscillation frequency as fluid flows through a vibrating tube, offering high accuracy across various fluids.

Coriolis Mass Flowmeter


  • True mass flow measurement: Directly measures mass flow without being affected by fluid density changes, making it ideal for applications requiring accurate mass flow measurements.
  • Additional temperature and density measurements: Often measures fluid temperature and density simultaneously, providing a comprehensive understanding of fluid properties.
  • Extremely high mass flow measurement accuracy: Offers exceptionally high accuracy, favored in applications needing precise mass flow measurements.
  • Highly accurate density measurement: Provides accurate fluid density measurements, crucial for process control and quality assurance in many fluid applications.
  • Unaffected by pressure, temperature, and viscosity: Measurement results are stable and reliable under varying conditions, not influenced by fluid pressure, temperature, or viscosity.
  • No need for inlet or outlet runs: Unlike some meters, Coriolis meters do not require specific straight inlet or outlet sections, allowing for flexible and convenient installation.


  • Potential for significant pressure loss: Measurement may result in substantial pressure loss, especially when measuring liquids with high saturation vapor pressures, possibly causing vaporization and cavitation, affecting system stability and reliability.

When selecting a Coriolis mass flowmeter, consider the following:

  • Operating pressure and pressure drop: Suitable for high-pressure applications but may not be compatible with applications requiring low pressure drops.
  • Price/accuracy trade-off: Increased accuracy comes at a higher cost, depending on the flowmeter type and flow.
  • Price/response time trade-off: Improving response time can be costly, with larger flow tubes having longer response times.
  • Price/preheat time trade-off: Equipment preheat time varies from seconds to minutes, with rapid preheat times crucial in some applications.
  • Flowmeter material: Detailed fluid composition information is necessary to assess corrosive/erosive properties.
  • Pipeline category: Serves as a starting point for material selection.
    Fluid behavior with solids and gases: Coriolis meters have specific limitations with two-phase flows, depending on the supplier's design.
  • Pressure drop limitations: Higher pressure drops may occur in process liquid calculations.
  • Usual fluid flow conditions/properties: Coriolis meters are typically selected to match pipeline size.

Coriolis mass flowmeters provide true mass flow measurement with high accuracy and density measurement. Additionally, they are unaffected by pressure, temperature, and viscosity and allow for flexible installation. However, it's important to note that Coriolis meters may cause significant pressure loss, especially when measuring liquids with high saturation vapor pressures. Therefore, when opting for a Coriolis mass flowmeter, one should carefully consider application needs and system characteristics, addressing pressure loss issues appropriately. [3]

5. Volumetric Flowmeter

Volumetric flowmeters measure the volume of fluid flowing through them, ideal for metering oil and chemical products.

Volumetric Flowmeter


  • Unobstructed flow path ensures smooth fluid flow, reducing resistance.
  • No moving parts mean stable operation with minimal maintenance.
  • No additional pressure loss during measurement, aiding system efficiency.
  • Insensitive to flow distribution, requiring only short inlet and outlet sections for accurate measurement.
  • Unaffected by changes in temperature, density, viscosity, concentration, and conductivity, offering wide applicability.
  • Good material choices available for chemically corrosive media.


  • Volumetric flow rate measurement is affected by temperature and pressure changes, necessitating corrections and compensation.

When selecting a volumetric flowmeter, consider the following:

  • Cleanliness requirement: Needs clean fluid, typically with a filtration level of 100µm.
  • Corrosion resistance: Many are not made from high-spec materials, which may be damaged by corrosive fluids.
  • Size limitations: Sizes increase rapidly with flow rate, rarely exceeding 12 inches.
    Fluid characteristic adaptability: Suitable for high viscosity and corrosive fluids, usually without the need for pre-filtration.
  • Easy maintenance: Simple structure makes maintenance and disassembly relatively easy.
  • Pressure drop considerations: There's a pressure drop to consider, especially when fluid viscosity changes.
  • Mechanical part wear: Over time, mechanical parts may wear and require replacement.

Volumetric flowmeters are crucial in various applications, offering smooth flow, stability with no moving parts, and efficiency without pressure loss. Yet, their accuracy can be impacted by temperature and pressure variations, requiring adjustments for precise measurements. They face challenges with high viscosity fluids and low flow rates, making it essential to consider fluid viscosity and flow rate range during selection. [4]

6. Vortex Flowmeter

Vortex flowmeters measure flow by detecting vortex frequency when fluids pass an obstacle, suitable for steam, gases, and liquids.

Vortex Flowmeter


  • No moving parts: One of the main advantages, ensuring reliability and longevity. It requires no routine maintenance, saving cost and time.
  • Durable structure: Built to withstand various industrial environments, often made from high-strength materials to endure pressure, temperature, and vibration.
  • Suitable for liquids, gases, and steam: With a broad application range, it’s a common solution for measuring different fluids, adding versatility.
  • Easy to sterilize: Often featuring smooth surfaces, making them easy to clean and sterilize. Ideal for sanitary measurement applications like food and pharmaceutical industries.
  • Unaffected by pressure, temperature, and density changes: Ensures stable and reliable measurements under varying operational conditions.


  • Requires inlet and outlet runs: To ensure stable flow characteristics near the measurement point, which might need extra installation space.
  • Needs a minimum Reynolds number: Requires sufficient flow energy to generate vortices. Measurement accuracy might be impacted at low flow rates where fluid dynamics may not produce enough vortex effect.

When choosing a vortex flowmeter, consider the following to ensure it fits your application needs:

  • Medium type: Suitable for measuring the flow of gases, liquids, and steam.
    Installation environment: Can be installed in any orientation, including vertical, horizontal, or any angle.
  • Process pressure and temperature: Ensure the selected meter can withstand the highest process pressure and temperature in your application.
  • Pipe size: Applicable to pipes from ½ inch to 12 inches or larger.
  • No moving parts: Reduces maintenance needs and enhances equipment reliability.
  • Sensitivity: Low sensitivity to changes in process conditions, meaning vortex flowmeters maintain accuracy in variable conditions.

Vortex flowmeters offer numerous advantages, such as no moving parts, durability, suitability for various fluids, ease of sterilization, and stability against changes in pressure, temperature, and density. However, they have limitations, including the need for proper inlet and outlet runs and a minimum Reynolds number. Selecting a vortex flowmeter requires considering the specific demands and limitations of your application to ensure accurate and reliable measurements. Proper installation and operation are crucial for achieving effective measurement outcomes. [5]

7. Turbine Flowmeter

Turbine flowmeters use the principle of turbine rotation to measure fluid flow, with the rotation speed proportional to the flow rate, suitable for clean liquids and gases.

Turbine Flowmeter


  • Rotating blade and Woltman turbine flowmeters operate without an external power source: These types utilize the pressure difference created by fluid flow to drive the rotation, saving energy costs and setup complexity.
  • Suitable for low-temperature liquids: Turbine flowmeters can measure low-temperature liquids, including refrigerants and cryogenic fluids, widely used in refrigeration technology and liquefied natural gas sectors.
  • Capable of operating under extreme temperatures and pressures: Turbine flowmeters withstand extreme conditions, making them suitable for specialized industrial environments.


  • Limited material choices: Turbine flowmeters have certain restrictions in material selection, especially for handling corrosive media or high-temperature, high-pressure conditions.
  • Best for low-viscosity liquids: Turbine flowmeters are sensitive to fluid viscosity, primarily used for measuring low-viscosity liquids, possibly not ideal for high-viscosity fluids.
  • Moving parts and wear: Containing components like rotating blades that may wear or get damaged over time, requiring regular maintenance and replacement.
  • Sensitive to contaminants: Susceptible to inaccuracies from solid particles or impurities in the fluid, necessitating regular cleaning and maintenance for accuracy.
  • Axial flowmeters affected by flow profile: Certain turbine flowmeters are influenced by the fluid flow profile, necessitating appropriate inlet and outlet lengths during installation for stable and accurate flow.
  • Inlet and outlet runs required (except for rotating blade type): Most turbine flowmeters need specific inlet and outlet lengths for stable entry and exit, though rotating blade types are more flexible.
  • Affected by overload and rapid pressure changes: Risk of overspeeding under rapid changes, suggesting cautious use under high differential pressure and considering pressure changes' impact on measurements.
  • Sensitive to vibrations: Therefore, proper vibration mitigation measures are needed during installation for stable and reliable measurement outcomes.

When selecting a turbine flowmeter, consider the following to ensure it meets your application needs:

  • Pipe diameter and flow range: Choose a suitable turbine flowmeter based on your pipe diameter and the flow range to be measured.
  • Temperature, pressure, and environmental conditions: Ensure the flowmeter withstands actual application conditions like temperature, pressure, humidity, and vibrations.
  • Accuracy, repeatability, and calibration: Determine the required accuracy and repeatability (typically 0.5-2%), considering calibration needs. Some turbine flowmeters support field calibration without disassembly.
  • Output signal, communication, and power: Decide on the needed output signal type (4-20mA analog, digital bus, pulse, frequency, etc.), and if intelligent communication protocols are required.
  • Installation requirements: Based on the application, determine the installation type (flange, threaded, clamp, or insertion).
  • Additional features and capabilities: Consider extra features as needed, such as integrated V-cone flow conditioners, accuracy verification diagnostics, data logging, etc.
    Budget constraints: Turbine flowmeter prices vary widely depending on size, material, accuracy, features, and communication capabilities. Establish budget limits.

Turbine flowmeters offer many advantages like operating without external power and suitability under special conditions. Yet, they also have limitations, such as restricted material choices and sensitivity to fluid viscosity. Therefore, when choosing and using turbine flowmeters, carefully consider their characteristics and limitations to ensure they meet specific measurement needs, and undertake appropriate installation and maintenance for accurate and reliable results. [6][7]

8. Differential Pressure Flowmeter

Differential pressure flowmeters calculate flow by measuring the pressure difference before and after a constriction component, suitable for various fluids.

Differential Pressure Flowmeter


  • High accuracy: Differential pressure flowmeters offer precision, ideal for applications requiring precise flow control and monitoring.
  • Broad application range: Suitable for various scenarios, they can measure both liquid and gas flows, meeting diverse needs in industrial processes and laboratory research.
  • Suitable for high-temperature and high-pressure applications: They function under extreme conditions, ideal for handling high-temperature and high-pressure media.
  • Low cost: Compared to other flow measurement technologies, differential pressure flowmeters are more affordable, making them a cost-effective option for budget-limited applications.


  • Regular maintenance required: To ensure accuracy and operation, they need periodic maintenance, including cleaning, calibration, and parts replacement.
  • Susceptible to wear and damage: Moving parts in differential pressure flowmeters may wear or get damaged, potentially reducing measurement accuracy or causing malfunction.
  • Limited accuracy at low flow rates: Their measurement precision is restricted at low flow rates due to the principle of operation, as the differential pressure signal at low speeds might be small and influenced by noise.

When selecting a differential pressure flowmeter, consider the following:

  • Pipeline size: Determines full-scale flow and primary element design.
  • Fluid type: Compatibility with liquids, gases, and steam.
  • Maximum operating pressure: Body/flange pressure rating.
  • Temperature limits: Temperature range for primary elements, sensors, and transmitters.
  • Viscosity range: High viscosity fluids may require special considerations.
    Required accuracy and turndown ratio.
    Allowed maximum permanent pressure loss.
  • Desired output: 4-20mA, HART, Profibus, Modbus.
  • Explosion-proof certification: ATEX, IECEx, FM, etc.
Moreover, best installation practices include paying attention to upstream and downstream straight pipe requirements to minimize turbulence and provide stable readings, and positioning pressure taps as recommended by the manufacturer to reduce flow disturbances.

Regular maintenance for optimal performance involves checking for damage or leaks in transmitters, sensors, and connections, repairing any impulse line blockages, and performing calibrations using external references or user-defined input calibrations.

Differential pressure flowmeters are widely used across various industries, from oil and gas, water treatment to chemicals and pharmaceuticals, favored for their high precision, reliability, and customizability.

Differential pressure flowmeters boast high accuracy, a wide application range, suitability for high-temperature and high-pressure applications, and cost-effectiveness. However, they come with the need for regular maintenance, susceptibility to wear and damage, and limited accuracy at low flow rates. Thus, when choosing and using differential pressure flowmeters, these advantages and limitations must be considered to ensure proper maintenance and operating conditions for accuracy and reliability. [8]


9. Laminar Flowmeter

Laminar flowmeters are designed for measuring low-speed, high-precision flows, commonly used in laboratories and medical applications.

Laminar Flowmeter


  • High precision: Laminar flowmeters provide extremely accurate flow data, making them popular in applications requiring high accuracy, such as laboratory applications and scientific research.
  • Suitable for low flow rates: They are ideal for applications needing precise measurement of low flows, offering reliable flow monitoring and control for stable fluid handling systems.
  • Low pressure drop: The pressure drop across a laminar flowmeter is relatively low, an important advantage for applications needing minimal energy consumption and fluid loss.
  • No moving parts: This means higher durability and no frequent maintenance or part replacements are needed.
  • Measures both liquids and gases: With a broad application range, laminar flowmeters can measure the flow of various liquids and gases, making them suitable for different fluid handling applications.


  • Limited application range: Mainly suitable for low flow rates, their measurement accuracy decreases under high-flow conditions, requiring consideration of flow speed limitations.
  • Prone to clogging: Laminar flowmeters can be easily clogged in applications with solid particles or viscous fluids, possibly leading to measurement errors or malfunction. Attention to fluid characteristics and appropriate cleaning and maintenance measures are necessary.

When selecting a laminar flowmeter, the main factors to consider include:

  • Fluid characteristics: Laminar flow occurs when viscous forces are greater than inertial forces, with minimal mixing and collisions among fluid molecules.
  • Reynolds number: Low Reynolds numbers indicate laminar flow, calculated based on fluid characteristics and flow conditions.
  • Pressure drop: Laminar elements typically consist of one or more tubes with length far greater than the diameter to generate slow flow speeds and measure the resulting pressure drop through a differential pressure sensor.
  • Temperature compensation: As laminar flowmeter measurement depends on fluid viscosity, which is strongly affected by temperature, all laminar flowmeters need temperature compensation, with some even using temperature control systems to keep the fluid temperature constant while passing through the element.
  • Accuracy: Alicat laminar differential pressure flowmeters and controllers use laminar differential pressure measurement technology, accurately measuring mass flow rates for over 130 gases.
  • Density correction for pressure and temperature: Laminar differential pressure mass flow instruments use volumetric flow rates and a series of density correction factors to calculate mass flow rates, including temperature density correction and pressure density correction.

Laminar flowmeters excel in precision and are ideal for low flow rates, with benefits like minimal pressure loss and versatility in measuring various fluids. Yet, their use is limited by a specific application range and clogging risks, necessitating careful selection, maintenance, and cleaning for optimal performance and accuracy. [9]

10. Thermal Mass Flowmeter

Thermal mass flowmeters calculate flow by measuring the heat required to cool a thermal sensor, suitable for gases and steam.

Thermal Mass Flowmeter


  • Direct gas mass flow measurement without needing pressure and temperature compensation.
  • No extra pressure and temperature compensation required, simplifying operation and calibration.
  • Minimal pressure loss, meaning little energy loss during flow measurement.
  • High measurement accuracy, providing reliable data for applications needing precision.
  • Wide measurement range, capable of accurately measuring from low to high flow rates.
  • No moving parts, leading to longer life and reduced maintenance.
  • Durable structure, withstanding significant pressure and vibration, suitable for harsh environments.
  • Quick response time, detecting and responding to changes in gas flow immediately.
  • Easy to sterilize, ensuring safety and hygiene in applications requiring sanitary conditions.


  • Only applicable to gases, not suitable for measuring liquids or other substances.
  • Requires specific inlet and outlet sections to ensure accurate measurement by providing a stable and uniform flow.

When choosing a thermal mass flowmeter, consider these key factors:

  • Accuracy and cost: Higher accuracy meters are more expensive, and even slight improvements in accuracy can significantly increase costs.
  • Response time: Meters with different response times vary in cost, with faster response times typically commanding higher prices.
  • Preheat time: Equipment preheat times can range from seconds to minutes, crucial for some applications.
  • Turndown ratio: The turndown ratio or operational range is an important performance metric, with significant differences between devices.

Thermal mass flowmeters offer many advantages such as direct gas mass flow measurement, no need for additional pressure and temperature compensation, low pressure drop, high measurement accuracy, wide range, no moving parts, durable structure, quick response time, and ease of sterilization. However, they are limited to gas flow measurement and require specific inlet and outlet sections for accuracy. Understanding the advantages and limitations of thermal mass flowmeters helps in selecting the right meter for specific application needs. [10]

11. Thermal Mass Flowmeter

Thermal mass flowmeters calculate flow by measuring the heat needed to cool a thermal sensor, suitable for gases and steam.

Thermal Mass Flowmeter


  • Direct gas mass flow measurement without pressure and temperature compensation.
  • No additional pressure and temperature compensation needed, simplifying operation and calibration.
  • Minimal pressure loss, indicating very little energy loss during measurement.
  • High measurement accuracy, offering reliable data for precision-required applications.
  • Wide measurement range, capable of handling various flow rates accurately.
  • No moving parts, leading to longer lifespan and lower maintenance needs.
  • Durable construction, capable of withstanding significant pressure and vibration.
  • Quick response time, allowing for immediate detection and response to gas flow changes.
  • Easy to sterilize, ensuring safety and hygiene in sanitary-required applications.


  • Only suitable for gases, not applicable for liquid or other substance measurements.
  • Requires specific inlet and outlet sections to ensure accurate measurement, as stable and uniform flow is needed to avoid measurement interference.

When choosing a thermal mass flowmeter, consider these key factors:

  • Accuracy and cost: High accuracy meters are pricier, depending on the type and flow rate, with slight accuracy improvements potentially increasing costs.
  • Response time: Different response times vary in cost, with faster times usually costing more.
  • Preheat time: Preheat times can vary significantly, with quick preheat times being crucial for some applications.
  • Turndown ratio: An important performance metric, with significant differences between devices.

Thermal mass flowmeters offer direct gas mass flow measurement, no need for extra compensations, low pressure drop, high accuracy, wide range, no moving parts, durable structure, quick response, and easy sterilization. However, they are limited to gas measurements and require specific inlet and outlet sections for accuracy. Understanding the pros and cons of thermal mass flowmeters aids in selecting the right meter for specific needs.


  1. ^ How to Choose the Right Ultrasonic Flow Meter - cross
  2. ^ What is an Ultrasonic Flow Meter? - OMEGA
  3. ^ 10 parameters for choosing the optimal mass flowmeter for an application -P.I. Process Instrumentation
  4. ^ A Guide to Positive Displacement Flow Meters - Flow Metrics
  5. ^ Positive displacement meters: pros, cons and selection - ENGINEERLIVE
  6. ^ Advantages of Vortex Technology - EMERSON
  7. ^ A Guide To Choosing The Right Turbine Flow Meter For Your Industrial Needs - Smart Measurement
  8. ^ Turbine Flow Meter Explained | Operation and Calibration - REALPARS
  9. ^ Differential Pressure Flow meters - OMEGA
  10. ^ Laminar Flowmeters - CONTROL AUTOMATION
  11. ^ Important considerations for choosing an electromagnetic flow meter -ESE MAGAZINE
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