12 Types of Flow Meters: Different Types of Flow Meters, Their Uses, and Their Advantages

A flow meter is a device used to measure the flow of gas or liquid through a pipeline. Choosing a flow meter depends primarily on factors such as fluid characteristics, operating environment, required accuracy, and budget. The following is a detailed introduction to different types of flow meters, their uses, and their advantages.

1. Positive displacement flow meter (PD flow meter for short)

Positive displacement flowmeters can be classified according to their measuring elements into oval gear flowmeters, scraper flowmeters, double rotor flowmeters, rotary piston flowmeters, reciprocating piston flowmeters, disc flowmeters, liquid-sealed drum flowmeters, wet gas meters and membrane gas meters.

Positive displacement (PD) flow meters measure flow by sampling a fixed volume of fluid and counting the number of times that volume is filled and drained. Unlike other flow meters that infer flow through indirect methods such as velocity or differential pressure, PD flow meters measure flow directly by dividing the fluid flow into discrete components. This method provides highly accurate flow measurement, making PD flow meters particularly suitable for billing and precise dosing control applications.

Industrial use

Positive displacement flow meters are used in a wide range of industries where high accuracy and precision are required:

- Water billing: Especially in residential and commercial applications, for accurate measurement of water usage.

- Chemical metrology: In the chemical industry, it is used to accurately measure and control the dosage of chemicals in process.

- Food and Beverages: For accurate portioning and measuring of ingredients and during bottling operations.

- Pharmaceuticals: In pharmaceutical production, precise quantities of liquids must be measured and controlled.

- Oil and Gas: For the measurement of hydrocarbons, particularly in custody transfer and billing applications where accuracy is critical.

- Paints and Coatings: For measuring and dispensing precise quantities of paints, dyes, and coatings.

benefit

- High metering accuracy: PD meters are extremely accurate and suitable for precise measurement of liquid media with high flow accuracy.

- Low flow capability: They can accurately measure very low flow rates, which other flow meters struggle to meet with high accuracy.

- Viscosity-independent: Its measurement accuracy is not significantly affected by the fluid's viscosity, making it ideal for a wide range of liquid types.

- Direct Read Measurement: Directly measures liquid volume, providing a true measurement of fluid flow without the need for conversion.

- Minimal need for straight pipe runs: PD meters are less sensitive to flow profile disturbances, allowing for more flexible installation options.

2. Differential pressure flowmeter

A differential pressure (DP) flowmeter is one of the oldest and most commonly used methods for measuring fluid flow in pipelines. Its basic principle is to measure the pressure drop across a constriction (or primary element) in the flow channel. Fluid accelerates as it flows through the constriction, resulting in a pressure drop between the upstream and downstream sides of the constriction. This pressure drop is proportional to the square of the flow rate, allowing the flow rate to be calculated from the measured differential pressure.

Industrial use

Differential pressure flow meters are used across a wide range of industries due to their versatility and reliability. Some common applications include:

- Water and wastewater management: used to measure water flow in treatment plants and distribution systems.

- Oil and gas industry: used to measure the flow of hydrocarbons in pipelines and refining processes.

- Chemical Manufacturing: Used to control and monitor the flow of various chemicals and reactants.

- Power generation: For steam flow measurement in boilers and cooling water in turbines.

- Food and Beverage: Used to manage liquid flows in processing and filtration systems.

benefit

- Versatility: Suitable for a wide range of fluids, including liquids, gases and steam, at various temperatures and pressures.

- Reliability and Durability: With no moving parts in the main elements, DP meters offer high reliability and a long service life.

- Accuracy: When properly calibrated and installed, they provide precise flow measurements suitable for many industrial applications.

- Proven Technology: The principles and practices of DP flow meters are well understood, with standardized calculations for the different major components.

- Cost-effectiveness: Especially for large pipe diameters, other types of flow meters are very expensive to install and maintain.

3. Velocity flow meter

Velocity flow meters directly measure the velocity of a fluid flowing through a pipe and use this information to calculate flow rate. Flow rate can be determined by multiplying the fluid velocity by the pipe's cross-sectional area. These meters are versatile and can be used with a variety of fluid types, including liquids, gases, and steam. There are several types of velocity flow meters, each using a different method to measure flow velocity.

Industrial use

Velocity flow meters have a variety of applications across a wide range of industries, including:

- Water Treatment and Distribution: Used to measure water flow in treatment plants and distribution systems.

- Chemical and pharmaceutical industries: Monitor and control the flow of chemicals, solutions, and other fluids during manufacturing processes.

- Oil and gas: used to measure hydrocarbon flow in pipelines and processing facilities.

- Food and beverage production: Ensure accurate flow rates of liquids (including water, oil, and other ingredients) in processing plants.

- Energy and Power Generation: Used to measure the flow of steam, cooling water, and other fluids associated with power generation.

benefit

- Versatility: Can be used with multiple fluid types and various pipe sizes.

- Non-obstructive to flow: Many velocity flow meters (e.g. ultrasonic, magnetic) do not intrude into the flow stream, minimizing pressure drops and risk of clogging.

- Accuracy: High precision, especially in clean, well-conditioned fluids.

- Digital Outputs and Connectivity: Many modern speedometers come with digital outputs and connectivity options for easy integration into control systems.

- Low maintenance: Non-intrusive designs such as magnetic and ultrasonic flow meters require less maintenance.

4. Mass flow meter

There are many types of direct mass flowmeters, such as calorimetric, angular momentum, gyroscopic, and dual-impeller types. These meters are suitable for measuring low-flow gases, but they have the disadvantages of being highly inert, with the measured value being related to the gas's specific heat at constant pressure, and the measuring element being in contact with the medium, making it susceptible to contamination and corrosion.

Mass flow meters directly measure the mass flow of fluid flowing through a device, unlike other types of flow meters that measure fluid volume and require a separate calculation to determine mass flow rate. This direct measurement is crucial in applications where process control or measurement accuracy requires measuring fluid mass rather than volume. The two most common mass flow meters are thermal mass flow meters and Coriolis flow meters, each operating on different principles to measure flow.

Industrial use

Mass flow meters are crucial in a variety of areas, including:

- Chemical and pharmaceutical industries: Precisely control ingredient addition in batch and continuous processes to ensure consistent product quality.

- Oil and gas: injection processes in upstream production, midstream custody transfer processes, and blending and refining processes in downstream operations.

- Food and Beverages: Used to accurately measure and mix ingredients to ensure consistent recipes and product quality.

- Semiconductor manufacturing: Precise control of gases and chemicals is critical to process consistency and yield.

- Environmental monitoring: used to measure emissions and compliance with environmental regulations.

benefit

- Direct measurement: Mass flow is measured directly and, unlike volume flow measurement, is not affected by temperature or pressure changes.

- Accuracy and Precision: Providing high accuracy and precision to ensure the consistency of material processing product quality is crucial for industry process control and optimization.

- No Moving Parts (Coriolis): Coriolis flow meters have no moving parts, resulting in lower maintenance costs and longer service life.

- Versatility: Can measure a wide range of fluids including gases, liquids and slurries.

- Multi-parameter measurement: Many mass flow meters can measure additional parameters such as density, temperature and viscosity, providing more data for process control.

5. Open channel flow meter

An open channel flowmeter is a device used to measure the flow of liquid in an open channel, where the liquid flows under the influence of gravity. Unlike closed pipes, the fluid in an open channel has a free surface exposed to atmospheric pressure. These flowmeters typically measure the height (or head) of the liquid in the channel and use this information, along with the channel geometry, to calculate the flow rate. The most common types of open channel flowmeters are weir and flume.

Industrial use

Open channel flow meters are used in a variety of applications, including:

- Water and wastewater treatment plants: Used to measure water and wastewater flows into and out of treatment facilities.

- Irrigation canals and ditches: monitor agricultural water distribution to ensure equitable and efficient use of water resources.

- Stormwater Management: Measuring runoff in open channels and culverts helps in flood prediction and water resource management.

- Environmental monitoring: for studying natural streams and rivers, tracking water use, and monitoring wastewater discharge.

- Mining and construction: for managing water used in these operations, including measuring flows in tailings.

benefit

- Simplicity and reliability: Open channel flow meters, especially weirs and flumes, have a simple design with no moving parts, resulting in high reliability and low maintenance requirements.

- Accuracy: If properly installed and maintained, they can provide good accuracy for measuring flow velocity in open channels.

- Versatility: Suitable for a wide range of flow conditions and water qualities, including those laden with sediment and debris.

- Cost-effective: Installation and operating costs are low compared to other flow measurement methods, especially for large channel sizes.

6. Magnetic flowmeters (Magmeters)

A magnetic flowmeter, also known as an electromagnetic flowmeter, consists primarily of a magnetic circuit system, a measuring conduit, electrodes, a housing, a lining, and a converter. According to Faraday's law, when a conductive fluid flows through a magnetic field, a voltage is generated. This voltage is proportional to the velocity of the fluid flowing through the field. By measuring this voltage, the flow rate can be determined. An electromagnetic flowmeter consists of a section of non-conductive pipe with electrodes placed on either side of the pipe and a coil to generate a magnetic field in the fluid.

Industrial use

Magnetic flowmeters are widely used in various industries due to their versatility and reliability:

- Water and Wastewater Treatment: Used to measure the flow of water, wastewater and treatment chemicals throughout the treatment process.

- Chemical Processing: For metering, chemical injection and processes where corrosive or abrasive liquids are present.

- Food & Beverage: For hygienic applications including measurement of food slurries, beverage production and cleaning processes.

- Pharmaceutical: For applications requiring high cleanliness and precise liquid flow measurement.

- Mining and mineral processing: for slurry flow measurement and mineral processing.

- Pulp and Paper Industry: For measuring alkaline and acidic liquids used in the papermaking process.

- Agriculture: for irrigation and water distribution.

benefit

- Accuracy: Provides high precision and repeatability for a wide range of flow rates and fluid conductivities.

- Versatility: Can measure virtually any conductive liquid, including corrosive and abrasive liquids.

- Low maintenance: With no moving parts and an accessible design, electromagnetic flow meters require less maintenance than mechanical flow meters.

- Suitable for dirty fluids: Effective in applications where the fluid contains solids or particles, such as slurries and wastewater.

- Easy to install: Can be easily installed in existing pipes without extensive modifications.

7. Vortex flowmeter

Vortex flowmeters operate on the principle of vortex shedding, where an obstruction (a bluff body) in a flow path causes alternating vortices to form on either side of the obstruction. The frequency of these shed vortices is proportional to the velocity of the fluid, allowing the flow rate to be calculated. This phenomenon is known as von Karman vortex shedding. Vortex flowmeters measure flow by counting these vortices over a period of time.

Industrial use

Vortex flowmeters have a wide range of applications due to their versatility and robustness:

- Chemical processing: used to measure the flow of chemical raw materials, solvents and process gases.

- Oil and Gas Industry: For measuring hydrocarbon liquids and gases, as well as steam in enhanced oil recovery processes.

- Utilities and Energy: For steam flow measurement in power plants and district heating systems, and for natural gas measurement in boilers and burners.

- Water and Wastewater: For measuring flow in treatment facilities and large-scale pipeline distribution.

- Food and Beverage: Suitable for steam and hot water applications, as well as flow measurement in production lines.

- Pharmaceutical: For measuring purified water, solvents and other process fluids.

benefit

- Accuracy and reliability: Measure the flow of gas, liquid and steam with good accuracy under different conditions.

- Low maintenance: No moving parts reduces wear and tear, thus lowering maintenance costs.

- Wide operating range: Effective over a wide range of flow rates and temperatures.

- Easy to install and use: Can be easily integrated into existing systems with minimal disruption.

8. Ultrasonic flow meter

An ultrasonic flowmeter is a flowmeter based on the principle that the propagation velocity of ultrasound in a flowing medium is equal to the vector sum of the average flow velocity of the measured medium and the velocity of the sound wave in a stationary medium. These flowmeters primarily consist of a transducer and a converter, and are available in different types, including Doppler, velocity difference, beam shift, noise, and correlation methods. Ultrasonic flowmeters use ultrasound to measure the velocity of fluids in a pipeline, thereby determining flow rate. They can be clamp-on (non-invasive) or in-line (invasive), with the former installed outside the pipeline and the latter inside the fluid. These meters utilize one of two main principles: Doppler shift or time difference of transit.

Industrial use

Ultrasonic flow meters are widely used and can be applied in various industries due to their non-invasive nature and wide range of fluids that can be measured:

- Water and Wastewater: For flow measurement in water distribution networks, wastewater collection systems and treatment plants.

- Oil and Gas: For hydrocarbon flow measurement in upstream, midstream, and downstream applications, including custody transfer and leak detection.

- Chemical and petrochemical industries: used to manage and control the flow of various chemicals and process fluids.

- Power Generation: Used to measure the flow of cooling water, steam and feed water in power plants.

- Food and Beverages: For hygienic applications where product contact is avoided.

- Pharmaceutical Manufacturing: Used to measure the flow of purified water, process fluids, and other critical fluids.

benefit

- Non-intrusive measurement: Clamp-on models require no piping modifications or interruptions to the installation process, reducing downtime.

- Broad fluid compatibility: Able to measure clean, dirty, viscous and fluids containing particles.

- No Pressure Drop: Since there are no moving parts or obstructions in the flow path, ultrasonic meters introduce no pressure drop.

- High precision and repeatability: transit time meters in particular have high precision under stable flow conditions.

- Versatile and flexible: can be used for temporary measurements or permanent installations on a wide range of pipe sizes and materials.

- Maintenance-free operation: With no moving parts and external mounting (for clip-on style), maintenance needs are minimized.

9. Thermal flow meter

Thermal flow meters measure the flow rate of fluids in pipes or ducts by monitoring the heat carried by the fluid (gas or liquid) as it passes through a heated element or sensor. There are two main types of thermal flow meter technologies: constant temperature anemometer (CTA) and constant power anemometer (CPA). CTAs maintain a constant temperature differential between two sensors, while CPAs maintain a constant power input to the heater. The flow rate is determined by the heat absorbed by the fluid, which is directly proportional to its mass flow rate.

Industrial use

Thermal flow meters are widely used in various fields due to their unique measurement capabilities:

- Environmental monitoring: used to measure emissions, including greenhouse gases and pollutants in flue gases.

- Chemical and petrochemical industries: used to control and monitor gas flows in processes, including inert gases, reactive gases, and corrosive gases.

- HVAC and Energy Management: For air flow measurement in ducts to optimize heating, ventilation, and air conditioning systems.

- Semiconductor manufacturing: used to control the flow of specialty gases during the manufacturing process.

- Pharmaceuticals: For measuring and controlling gases during production and packaging processes.

- Biotechnology: for monitoring fermentation gases and other process flows.

benefit

- Accuracy and Repeatability: Provides precise and repeatable measurements, which are critical for process control and monitoring.

- Low maintenance: No moving parts means less mechanical wear and tear and lower maintenance costs.

- Versatility: Can measure a wide range of gases, including corrosive and toxic gases, without the need for fluid property calibration.

- Easy to Install and Use: Compact and easy to install in various directions and positions, including tight spaces.

- Minimal Pressure Drop: Since they generally do not significantly intrude into the flow path, they introduce minimal pressure drop.

10. Turbine flowmeter

A turbine flowmeter measures the flow rate of a fluid (liquid or gas) flowing through a pipeline using a turbine or rotor placed in the fluid stream. As the fluid flows through the meter, it strikes the turbine blades, causing the turbine to rotate. The speed of the turbine rotation is proportional to the velocity of the fluid, allowing the flow rate to be calculated. The rotational speed is typically detected by a magnetic pickup, optical sensor, or other means, generating an electrical signal proportional to the flow rate.

Industrial use

Turbine flow meters are versatile and are used across various industries due to their accuracy and reliability:

- Oil and Gas: Widely used for measurement of hydrocarbon liquids and gases in production, refining, and distribution, including custody transfer applications.

- Chemical and petrochemical: Used to accurately measure process fluids to facilitate process control and inventory management.

- Water and Wastewater: For measuring water flow in treatment plants and distribution systems, as well as in irrigation systems.

- Food and Beverage: Used to monitor the flow of raw materials, water and other process liquids to ensure consistent product quality and batch control.

- Pharmaceuticals: For manufacturing processes where precise metering and flow control of liquids are crucial.

- Aerospace and Automotive: Used to test and monitor fuel flow rates.

benefit

- Reliability: With proper installation and maintenance, turbine flow meters can provide many years of reliable service.

- Adjustable Range: Suitable for a wide range of flow rates from very low to very high without sacrificing accuracy.

- Easy to maintain: The design is easy to clean and maintain, which is especially beneficial in applications using clean fluids.

- Compatibility: Can be used with a wide variety of fluids, including liquids and gases, as long as they are clean and non-corrosive.

11. Gear flow meter

Gear flowmeters, also known as positive displacement flowmeters, use the mechanical action of rotating gears to measure fluid flow. As fluid flows through the meter, it enters the compartment formed between the gears and the metering chamber, causing the gears to rotate. Each rotation of the gears represents a specific volume of fluid flowing through the meter, allowing the total flow rate to be measured with high accuracy. Flow rate is determined by counting the number of rotations in a given period of time, typically using magnetic, optical, or mechanical sensors.

Industrial use

Due to their accuracy and versatility, gear flow meters are used in various industries, including:

- Chemical and Petrochemical: Used to measure the flow of chemicals, solvents, and other process fluids where precise dosage and flow control are critical.

- Oil and Gas: Applications such as lubrication systems, hydraulic systems, and fuel metering require precise measurement of viscous fluids.

- Food and Beverages: For metering and batching of ingredients, where hygiene and accuracy are crucial.

- Pharmaceuticals: Metering precise volumes of liquids during manufacturing, particularly in formulation and filling operations.

- Paints and coatings: Used to control the flow of viscous materials and ensure accurate mixing ratios.

- Automotive: Fuel consumption and lubricant measurements on test benches.

benefit

- Accuracy: Provides excellent accuracy and repeatability, which are critical for process control and quality assurance in many industrial applications.

- Versatility: Suitable for a wide range of fluids, including those that are viscous, shear-sensitive, or contain particles (as long as they do not interfere with gear movement).

- Minimal straight pipe requirements: Unlike many other types of flow meters, gear flow meters require minimal upstream and downstream straight pipe runs, making them suitable for installation where space is limited.

- Durability: Strong structure, able to withstand various operating temperatures and pressures.

12. Coriolis flow meter

Coriolis flowmeters, based on the Coriolis effect, are widely recognized for their ability to directly measure the mass flow rate and density of fluids (liquids or gases) flowing through a pipe. The Coriolis effect describes the deflection of a moving object when viewed in a rotating reference frame. In these flowmeters, a fluid flows through a vibrating pipe; variations in the fluid's mass flow rate cause a measurable distortion, or phase shift, in the pipe vibrations, proportional to the mass flow rate. This technology offers high accuracy and direct measurement without the need to compensate for temperature, pressure, or viscosity changes.

Industrial use

Due to their accuracy and versatility, Coriolis flow meters are used in a wide variety of applications:

- Chemical processing: Accurate metering and measurement of reactants and products is crucial in processes where material balance is critical.

- Oil and Gas Industry: In upstream, midstream, and downstream applications, including custody transfer, measurement accuracy directly impacts revenue.

- Food and Beverage: Used to manage ingredients in recipes, ensuring consistent product quality and compliance with industry standards.

- Pharmaceutical Manufacturing: In formulations, precise measurement of ingredients is crucial for product efficacy.

- Power generation: for fuel measurement and processing to optimize combustion processes and efficiency.

benefit

- No moving parts: Minimizes maintenance needs and extends service life.

- Independent of fluid properties: Remains accurate over a wide range of temperatures, pressures, viscosities and densities.

- Efficiency and Accuracy: Significant cost savings can be achieved through precise fluid measurement and reduction of waste in process industries.

- Rugged: Operates reliably in harsh environments and with corrosive or abrasive fluids.