What is a Flow Meter? Types & Benefits Explained

A flow meter is a device used to measure the rate, quantity, or velocity of fluid moving through a system. Fluids include water, other liquids,  gases, and steam. Flow meters are widely used across multiple industries, including water management, oil and gas production and management, chemical processing, HVAC, food and beverage, pharmaceuticals, and power generation.

Each application has different requirements, so there are multiple varieties of flow meters that utilize different technologies and mechanisms. Types of meters include ultrasonic, electromagnetic, Coriolis, thermal mass, and positive displacement flow meters. 

In this article, we’ll discuss what flow meters are, how they work, what types of flow meters are available, why flow meters are used, and how to choose the right one for your desired application.

What Is a Flow Meter?

A flow meter is a flow-measurement device installed in or around a pipe or process system to measure the amount of fluid passing through a point. Flow meters may measure flow rate, which is how quickly fluid moves, or totalized flow, which is the accumulated quantity of fluid passing through the meter over time.

Flow meters can measure the volume of fluid passing through the meter or the actual mass of fluid instead. We call these volumetric flow meters and mass flow meters, respectively.

Volumetric flow meters measure the volume of fluid passing through the meter during a given period of time. Examples of volumetric flow meters include electromagnetic, ultrasonic, turbine, and positive displacement meters. Positive displacement meters are true volumetric meters because they measure fluid by directly and repeatedly trapping known volumes and counting the cycles.

In contrast, mass flow meters measure the actual mass of fluid passing through the meter. As fluid density can vary with conditions such as temperature, pressure, or fluid composition, mass flow meters are essential for many applications. Examples of mass flow meters include Coriolis flow meters and thermal mass flow meters. 

Meters can be installed in several different ways, including inline, insertion, and clamp-on. 

Inline meters are installed directly into the pipeline and are commonly used in chemical plants, factories, and in utilities metering. Insertion meters consist of a sensor inserted through an opening into the pipe. These are useful for large pipes where full inline installation is expensive. Clamp-on meters are sensors which attach externally to the pipe, with no need for cutting. 

How Does a Flow Meter Work?

So how does a flow meter work? Although there are different types of flow meters, they all work by converting the physical movement of a fluid into a measurable signal that can be used to determine the flow rate.

Different types of meters detect one or more properties of the fluid: velocity, pressure difference, electrical conductivity, thermal behavior, mechanical movement, or vibration effects. The transmitter converts these measurements into flow rate, total flow, digital outputs, and monitoring data. There’s no single mechanism for this, as each type of flow meter functions differently. 

Here, we’ll consider the major working principles for flow meter types in this simple table:

Mechanical Displacement	Moving fluid drives internal meter components that capture known quantities of fluid. The meter counts these movements to calculate the flow.
Differential Pressure	A restriction in the pipe creates a pressure difference between the upstream and downstream points, allowing the meter to calculate flow from the differential pressure.
Electromagnetic Induction	When conductive fluid moves through a magnetic field, it generates a voltage proportional to flow velocity. This type of measurement is suited for conductive liquids such as water.
Ultrasonic Measurement	There are two types of ultrasonic measurement: transit-time, which compares the time taken by ultrasonic waves travelling with and against the fluid flow, and Doppler ultrasonic, which calculates flow by monitoring frequency shifts caused by ultrasonic waves hitting particles or bubbles moving within the fluid.
Thermal Measurement	Flow is measured by detecting the heat carried away from a heated sensor as the fluid passes through the meter. Because heat transfer varies with flow velocity and gas properties, the meter can directly calculate the mass flow rate.
Coriolis Measurement	When fluid moves through vibrating tubes inside the meter, mass flow can be determined from the twisting forces this creates. This can produce highly accurate measurements of mass flow and density.

What Does a Flow Meter Do?

Flow meters use different technologies to measure the speed and volume of liquids or gases passing through a pipe. Their applications span across many sectors, from oil and gas to municipal water systems. In oil and gas, knowing flow direction, speed, and potential leaks is critical for strategic, operational, and financial reasons. 

In water systems, flow meters track where water is going, how fast, and when. They monitor networks for leaks, identify areas of waste, and help ensure water reaches its intended endpoints. These devices are found in cities and towns’ infrastructure, and the data they provide is essential for planning, adequate provision, and timely maintenance. 

Key functions include:

• Measuring usage: Flow meters track how much water is used by households or entire communities for planning and billing.
• Monitoring sewage flow: Flow metering can help verify whether sewer systems meet usage demands.
• Detecting leaks and inefficiencies: Flow meters can identify irregular patterns that may indicate system failures or inefficiencies.
• Confirming delivery: A flow meter can monitor systems to help ensure water reaches its intended destination within complex infrastructure and that the resident is billed fairly for what is used.

Benefits of Flow Meters

Now that we understand what flow meters are, how they work, and what they’re used for, we can discuss the benefits of using them. Flow meters are best thought of as tools for more effective, efficient, and purposeful management of fluids, whether that’s for utilities monitoring, industrial applications, or any other purpose.

The key benefits across industries and applications include:

• Accurate billing and cost allocation: Flow meters allow organizations to measure exactly how much fluid each user, department, or process consumes. This supports better cost forecasting and better billing.
• Process optimization: Real-time flow measurement helps operators balance systems, improve production efficiency, and maintain consistent processes. It can enable better energy allocation through more comprehensive tracking, supporting more efficient processes.
• Regulatory compliance: Many industries require accurate measurements for environmental reporting, safety controls, and production standards. Accurate flow meters help meet these regulatory requirements.
• Resource conservation: Flow measurement helps identify leaks, excessive consumption, and inefficient processes that can lead to significant fluid waste, resulting in negative financial and environmental impacts.
• Preventative maintenance: Changes in expected flow patterns can indicate issues such as equipment wear, blockages, and pump problems that, if left unaddressed, could cause significant damage.
• Reduced operating costs: Better management reduces wasted materials, unnecessary energy use, and manual inspections that tie up resources that could be used elsewhere. By streamlining management, operating costs can fall.

Types of Flow Meters

While all flow meters measure flow, they do so using different technologies. Each type has specific strengths and limitations:

• Electromagnetic Flow Meters (Mag Meters)
  Use magnetic fields and electrodes to measure the voltage generated by conductive liquids like water. They are highly accurate, have no moving parts, and require minimal maintenance.
• Ultrasonic Flow Meters
  Send ultrasonic signals through the water and calculate flow based on the time it takes the signal to travel. These meters are non-intrusive, provide real-time data, and are low-maintenance — though air bubbles or debris can impact accuracy.
• Differential Pressure Flow Meters
  Measure the pressure drop across a constriction in the pipe. These are reliable and widely used, but they may reduce overall system pressure and require careful calibration.
• Vortex Flow Meters
  Use a bluff body (obstruction) in the flow stream to create vortices, which are then measured to determine flow. They’re durable and require little maintenance, but are generally less precise than other advanced technologies.
• Coriolis Flow Meters
  Measure the mass flow using vibrating tubes and Coriolis forces. Fluid moves through vibrating tubes in the meter, creating a twisting force that allows measurement of mass flow. They work with liquids and gases and offer very high accuracy, but are more expensive and larger than other meters.
• Thermal Mass Flow Meters
  Measures how heat transfers from a heated sensor into a moving gas. They’re primarily used with gases, and often in compressed air monitoring, gas distribution, and industrial processes. They directly measure mass flow and are excellent for low gas flows but have limited liquid applications.
• Turbine Flow Meters
  Fluid spins an internal rotor, and the rotor speed correlates with flow velocity. These are commonly used with clean liquids and gases. They’re accurate with a relatively simple design, but moving parts require maintenance.
• Positive Displacement Meters
  Fixed fluid volumes are mechanically captured and displaced. These displacement cycles are measured to determine flow. They’re used often in fuel measurement, oil systems, and applications requiring precise liquid measurements. They’re highly accurate at low flow rates, but moving components wear over time.

Let’s take a look at some of the pros and cons of each type of meter in an easy-to-visualize table form:

Type of Meter	Pros	Cons	Best For
Positive Displacement Meter	AccurateDoes not require a power source	High maintenanceCan restrict water flow	Clean, viscous liquidsPrecise volumetric measurement
Electromagnetic Flow Meter	Highly accurateLow maintenance	Higher initial costRequires powerAffected by temperature, pressure, and electromagnetic interference	Water, wastewater, conductive chemicals
Ultrasonic Flow Meter	Highly accurateDurableLow maintenance	Requires powerLess accurate in aerated or particulate-laden fluids	Water systems, HVAC, industrial processes, temporary flow monitoring
Vortex Flow Meter	Low maintenanceSuitable for clean liquids, gases, and steam	Flow obstruction may cause pressure dropNot ideal for high-viscosity fluidsReduced accuracy at low flow rates	Steam, clean liquids, gases, and industrial processes
Differential Pressure Flow Meter	Versatile technology suitable for liquids, gases, and steam	Reduces system pressureRequires regular maintenanceProne to clogging depending on design	Oil and gasChemical processingHVACPower generation
Coriolis Flow Meter	Extremely accurateMeasures mass flow directlyCan also measure density and temperature	Higher initial costHeavier than other meter typesCan create higher pressure drops	High accuracy applications in oil and gasChemicalFood and beverage processingPharmaceuticals
Thermal Mass Flow Meter	Direct mass flow measurementExcellent for gasNo moving parts	Primarily suitable for gasesRequires powerAccuracy can be affected by changes in gas composition	Compressed air, natural gas, industrial gas monitoring
Turbine Flow Meter	Good accuracyFast ResponseCost-effective for clean fluids	Moving parts require maintenancePerformance is affected by dirty or viscous fluids	Clean liquids and gases

Flow Meter Applications by Industry

Flow metering is widely applicable and is used across multiple industries, including water management, pharmaceuticals, and food and beverage processing. These diverse industries often require vastly different implementations of flow metering, for example, due to precision and measurement requirements or the types of fluids being measured. 

In this section, we’ll consider use cases for flow metering in various industries: water management, oil and gas, chemical processing, HVAC and building systems, food and beverages, and pharmaceuticals.

Flow Meters in Water Management

In water management, flow meters measure water flow. Multiple kinds of flow meters are commonly used across water management, whether in industrial treatment, utilities, or residential water submetering. Water management is one of the major use cases for flow metering.

Flow meters are foundational to modern water infrastructure. They provide the real-time and historical data needed for system performance monitoring, regulatory compliance, and better resource planning. Whether in single-family homes or city-wide networks, accurate flow measurement is critical to managing water wisely.

Flow meters play a role across every stage of the water cycle from source to residents. Depending on the type and setup, they support:

• Leak detection and conservation: When integrated with smart systems, flow meters can help detect anomalies and reduce repair costs by catching issues early.
• Water system monitoring: Track flow performance in residential, commercial, and municipal systems to ensure efficient distribution.
• Wastewater tracking: Monitor treatment plant capacity and optimize process performance.
• Regulatory compliance: Flow meters provide required consumption data for accurate billing and environmental reporting and may be mandated by local codes.
• Stormwater and flood management: Flow measurement helps manage high-flow events, especially in drainage and overflow infrastructure.
• Water submetering: Submetering in multi-tenant buildings, apartment complexes, commercial buildings, and industrial settings allows water consumption to be tracked individually at the unit level, enabling precise data collection at very granular scales, such as a single industrial machine or zone, or a single apartment in residential housing. Smart water meters enable remote monitoring, automated meter readings, and leak alerts through connected communication networks. 
• Billing accuracy: Water flow meters, especially when paired with submetering systems, provide much better billing accuracy because precise water consumption can be measured, identified and allocated to specific units. This means users can be billed based on actual measured consumption instead of estimated usage.

Various types of flow meters are used in water management, as operational requirements vary significantly depending on the specific use case. Ultrasonic meters are increasingly common, while traditional mechanical, turbine-based meters remain popular options. 

Flow Meters in Oil and Gas

Even very small measurement errors can have significant operational and financial consequences, so flow management is an essential part of the process from extraction through to refining and distribution. 

As flow meters are used to measure crude oil, refined fuels, natural gas, steam, water, and chemicals, the requirements vary at different stages of the production and distribution process. 

Flow metering plays an important role across the pipeline:

• Upstream production
• Midstream transportation
• Custody transfers
• Downstream refining

Common meter types used in oil and gas include Coriolis, ultrasonic, and differential flow meters. Coriolis meters are commonly used in custody transfers because they directly measure mass flow with excellent accuracy, which is vital for commercial transactions. 

Flow Meters in Chemical Processing

Chemical processing requires accurate flow measurement to maintain product quality, process efficiency, and plant safety. Flow meters are essential instruments used at every stage of chemical processing and production. They commonly handle hazardous, high-temperature, viscous, and conductive fluids of various kinds, necessitating reliable operation in demanding environments.

Flow meters are typically used to support:

• Raw material processing
• Chemical dosing and blending
• Batch production
• Process monitoring

Common meter types include electromagnetic and Coriolis flow meters because they can handle aggressive chemicals and provide accurate mass flow data necessary for batch processing and dosing accuracy.

Flow Meters in HVAC and Building Systems

Flow meters in HVAC and building systems are typically intended to support efficient heating, cooling, and energy management in commercial, industrial, and institutional settings. Flow meters continuously measure chilled water, hot water, condenser water, and steam. 

Flow meters are typically used in these scenarios:

• Heating and cooling system monitoring
• Energy metering
• Building performance optimization

Ultrasonic and electromagnetic meters are typical here.

Flow Meters in Food and Beverage

In food and beverage production and processing, flow metering helps manufacturers maintain product consistency, quality, food safety, and production efficiency. Flow meters are often used to measure liquids such as water and also more viscous liquids. 

Flow measurement is an essential component of the food and beverage production process, used in multiple different parts of the process:

• Ingredient dosing
• Production monitoring
• Clean-in-place systems
• Quality assurance

Coriolis meters are commonly used for high-accuracy ingredient measurements and hygienic processing, while electromagnetic flow meters are widely used for various conductive food products.

Flow Meters in Pharmaceuticals

Pharmaceutical manufacturing is a tightly regulated industry that involves numerous high-value ingredients and requires extremely accurate measurements throughout the production process for operational, safety, and regulatory purposes. Flow meters are an essential component for maintaining product quality, regulatory compliance, and consistency across batches.

Flow meters monitor various liquids, purified water, process gases, and sterile production systems. They’re vital tools that help in:

• Precision dosing
• Batch manufacturing
• Sterile manufacturing
• Regulatory compliance

Coriolis and thermal mass meters are common in pharmaceuticals processing because of the necessity of high accuracy at small volumes.

Smart Flow Meters and IoT Integration

Modern flow metering approaches utilize innovative new technologies to deliver substantial improvements over traditional flow metering. These smart approaches consist of an all-new technology layer added to the traditional flow metering process; smart flow metering has evolved far beyond simple measurement. Today, smart flow meters are integrated into broader IoT systems that enable digital communication, data processing, and remote management.

This integrated approach provides unprecedented insight that enables organizations to collect, analyze, and utilize flow data more efficiently than ever before, without relying on manual readings or local inspections. As such, they’re increasingly common across industries and contexts where visibility across large asset networks is a necessity. This means smart flow meters and IoT networks are used extensively in diverse contexts, including water distribution systems, industrial plants, commercial buildings, energy networks, and more.

But what makes a smart flow meter “smart”? 

What Makes a Smart Flow Meter Smart?

Smart flow meters typically combine three separate layers:

• Measurement technology
  The underlying meter provides the same core measurement functionality as in traditional meters. Therefore, smart flow meters may utilize any of the measurement technologies discussed previously, such as an ultrasonic water meter or a thermal mass flow meter.
• Digital processing and diagnostics
  Modern flow meters include systems that process raw sensor signals and convert them into usable measurement data. Smart flow meters may include features such as improved signal processing, automatic error detection, device health monitoring, and measurement status information.
• Communication and connectivity
  Smart flow meters transmit measurement data to external systems, eliminating the need for manual meter readings. They achieve this through multiple communication methods, including LoRaWAN, NB-IoT, cellular, and WiFi connectivity.

The communication layer is particularly important for smart flow metering, as it provides the networking capabilities that underpin smart integrations. For example, LoRaWAN is a low-power, wide-area networking technology designed for long-range communication between connected devices. It’s commonly used where devices need to transmit small amounts of data over long distances while conserving battery power, which is a typical smart flow metering use case. 

Other approaches include NB-IoT, a cellular communication technology designed specifically for IoT devices, and WiFi connectivity, which is commonly used in buildings and local systems where network access is available.

Smart Meter Data Management

Smart flow meters generate a continuous stream of measurement data rather than occasional manual readings. This level of data supports diverse applications, but requires additional management. Smart flow metering systems require a data management platform to support this. 

Data management platforms are useful for data logging, enabling smart meters to store historical readings. Historical data allows managers to review consumption patterns, compare performance over time, and investigate unusual behavior against an historic record. They also support remote monitoring, enabling managers to view flow data without physically visiting each meter location. This is particularly valuable in large networks such as municipal water systems or industrial facilities.

In industrial settings, SCADA (Supervisory Control and Data Acquisition) systems are monitoring and control platforms used to collect equipment data and provide key visibility into processes. Smart flow meters can send measurement data to SCADA systems, allowing operators to monitor flow alongside other operational information. 

Benefits of Smart Flow Meters Compared With Traditional Flow Meters

Smart flow meters provide all the traditional benefits of flow metering, with additional benefits from their communication and networking capabilities. These benefits include:

• Automated data collection: Networked meters reduce reliance on manual readings, enabling continuous, automatic data collection and transmission, reducing site visits while improving visibility far beyond traditional systems.
• Remote diagnostics: Smart meters can automatically and remotely provide information on device status and operating conditions, allowing operators to identify issues without physically inspecting every meter.
• Predictive maintenance support: Historical flow data can help identify abnormalities that indicate developing problems, while managers can use trends and alerts to investigate equipment before failures occur.
• Centralized management: Large networks can be managed from a single interface, improving visibility, enhancing response times, and simplifying asset management.

How to Choose a Flow Meter?

Selecting the right flow meter requires more than knowing the pipe size or required flow rate. The best meter depends on a combination of factors including the type of fluid being measured, required accuracy, typical operating conditions, installation constraints, maintenance requirements, and total cost.

There is no universal “best” flow meter. As such, it’s important to consider your specific requirements before deciding. 

The following selection criteria are essential to consider before choosing a flow meter:

• Fluid type
  Different kinds of flow meters work better with some fluids than others. Properties that influence suitability include conductivity, viscosity, density, presence of suspended solids, temperature, and pressure. For example, positive displacement meters work well with clean liquids, but not with heavy slurries.
• Accuracy requirements
  Basic monitoring may not require the same precision as high-value commercial transactions or safety requirements, such as in oil and gas custody transfers.
• Flow range
  Flow range describes the minimum and maximum flow rates a meter can measure. Selecting a meter only for maximum flow means it might perform poorly at low flows, and vice versa. 
• Operating conditions
  Various operating conditions, such as temperature, pressure, viscosity, and chemical compatibility, affect the suitability of flow meters. High pressure systems may require specialized meters, and not all meters are suitable for all chemical environments.
• Installation method
  Installation requirements can significantly influence which types of meters are suitable in a given deployment. Inline meters may not be a viable option, especially where pipes are very large. Installation requirements often determine which meters are suitable.
• Maintenance requirements
  Maintenance requirements vary between flow meter technologies. Meters with moving parts often require more maintenance than those without, such as ultrasonic meters. If your meter needs to be placed in a location that makes maintenance difficult, selecting a low-maintenance meter type should be a priority.
• Budget
  Budgets are a major constraint, but the cheapest upfront cost isn’t always the lowest-cost option over the meter lifecycle. It’s important to consider purchase and installation costs, as well as lifetime operating costs including maintenance, calibration, replacement parts, and energy requirements.

Flow Meter vs Flow Controller

Flow meters and flow controllers are related, but perform different functions; they’re not the same thing. Flow meters measure flow, but flow controllers both measure flow and use that data to adjust fluid flow using control valves to maintain the desired conditions. Flow controllers are part of a feedback control system.

Flow controllers are typically used in industrial manufacturing, laboratories, and process automation systems. 

Flow Meters With Mainlink — More Than Simple Measurement

Flow ultrasonic meters are more than just measurement devices. They are strategic tools for delivering smarter, leaner, and more resilient water infrastructure benefiting utility providers, property managers and residents.

In a world where water efficiency, cost control, and sustainability are top priorities, flow meters  play a critical role in modern infrastructure. Whether you’re managing a multifamily property, a commercial facility, or a municipal water network, investing in a reliable, accurate, and scalable flow metering system is a strategic decision. With smart technology, you’re not just tracking usage – you’re unlocking control, unprecedented levels of insight, and long-term value. 

Contact us for an advanced flow meter solution for your project. 

Frequently Asked Questions

What is a flow meter used for?

Flow meters measure the flow of fluids, such as water, gases, or steam, as they move through a pipe or space. They are used for monitoring, control, billing, and optimization purposes across a variety of industries.

What is the difference between a mass flow meter and a volumetric flow meter?

Volumetric meters measure fluid volume per unit of time, whereas mass flow meters measure mass per unit of time. 

What type of flow meter is most accurate?

There is no single answer, as accuracy depends on application. No single meter is universally the best, as each meter type has preferred use cases.

Can a flow meter measure both liquids and gases?

Yes, a flow meter can measure both liquids and gases. Coriolis meters and ultrasonic meters, for example, can measure both.

How do ultrasonic flow meters work?

Ultrasonic flow meters use ultrasonic signals to determine fluid velocity. Transit-time and Doppler methods are the main approaches. In transit-time, the time taken for ultrasonic waves to travel along the pipe is measured. In Doppler, frequency changes of an ultrasonic wave as it hits particles in the water is used instead.

What is a clamp-on flow meter?

Clamp-on flow meters are external sensors that attach to the outside of a pipe and do not require cutting the pipe or inserting them into the fluid.

Do flow meters need calibration?

Yes. Calibration verifies that the meter continues producing accurate measurements. However, many meters do not require additional calibration by end users.