Flow measurement is crucial for controlling liquid and gas flows. A flow meter measures the volume flow in the pipe, guarantees accuracy and ensures process quality.
Table of contents
- What is flow measurement?
- Meaning and areas of application
- Different measuring methods
- Essential components of a flow meter
- Types of flow meters
- Application and selection of flow meters
- Criteria for selecting the right flow meter
- Norms and standards in flow measurement
- Product categories Flow meters
- FAQ - Frequently asked questions
What is flow measurement?
Flow measurement refers to the process of precisely determining the volume flow of gases or liquids in a pipe. Special flow meters record the volume flow in order to take important measurements. This data is essential for users to ensure accuracy in various processes. Correct measurement helps to increase efficiency and minimize potential sources of error. There are many different flow meters that can be selected depending on the medium and requirements.
You can find more detailed information on the diversity of flow measurement in the blog article "Diversity of flow measurement".
Significance and areas of application
Flow measurement plays an essential role in many industrial sectors as it provides accurate information about the volume flow of media such as liquids and gases. This measurement is crucial for various applications, from optimizing industrial processes to ensuring product safety. Flow meters are often used in the chemical industry, water treatment and the energy sector to precisely control the flow in the pipe.
Efficient flow measurement in air ducts as well as technology and application examples are described in our Blog article on flow measurement in air ducts.
Various measurement methods
There are numerous methods for measuring flow rates that are based on different physical principles. Mechanical methods use physical elements in the medium to determine the flow rate. Magnetic-inductive methods measure the flow of electrically conductive liquids through a magnetic field. Ultrasonic methods are based on sound waves to measure the volume flow. Thermal methods determine the flow through temperature differences. The selection of the appropriate method depends on the specific application, the medium and the process conditions.
Further basics on fluid dynamics (laminar/turbulent) and their importance for precise measurements can be found in the Blog article "Laminar vs. turbulent - flow in flow measurement".
- Mechanical methods
Mechanical methods for flow measurement use moving parts to determine the flow rate of a medium. A typical example is the variable area flow meter, which measures the volume flow based on the position of a floating body in the pipe. This method is particularly suitable for measuring liquids. The simplicity of these flow meters ensures cost efficiency, but wear and pressure loss can affect their accuracy.
- Magnetic-inductive methods
Magnetic-inductive methods use the principle of electromagnetic induction for flow measurement. This method is particularly suitable for electrically conductive liquids. A magnetic field is generated around the pipe and the liquid flow induces a voltage that is proportional to the flow rate. This method offers high accuracy and no moving parts in the medium, which minimizes wear. Users particularly appreciate this type of flow meter in the water and process industries.
- Ultrasonic method
Ultrasonic methods measure the flow by sending sound waves through the medium and analyzing their transit time or frequency shift. This technology is suitable for gases and liquids and offers the advantages of high accuracy and flexibility. Ultrasonic flow meters are contactless, which is important for hygienic applications. They are ideal in the food and beverage industry as well as in water treatment where low flow disturbance is desired.
- Thermal processes
Thermal methods for flow measurement use temperature changes to determine the flow rate of gases. A heated sensor is placed in the medium and the temperature difference caused by the flow is measured. This method is particularly suitable for low flow velocities and offers high accuracy. Thermal flow meters are low maintenance and are often found in laboratory applications where sensitive measurements are required. They are effective at constant fluid composition and stable process conditions.
Essential components of a flow meter
Flow meters consist of several essential components that together measure the volume flow. Sensors record the physical properties of the medium, from which the flow rate is calculated. Transmitters convert the sensor data into a usable signal that is used for process control or to output information. The pipe serves as an integrated flow channel through which the medium is passed. The choice of materials and design depends on the process conditions and the desired accuracy.
- Sensors
Sensors are critical components of a flow meter as they directly measure the physical parameters of the medium. Depending on the measuring method, sensors can use magnetic, thermal or acoustic signals to determine the flow rate. The choice of sensor has a significant influence on accuracy. A suitable sensor must meet the requirements of the specific process, be it for high temperatures, different pressure conditions or special flow characteristics in the pipe.
- Transmitter
Transmitters are crucial for processing and transmitting the sensor data of a flow meter. They convert the recorded signals into electrical signals that can be used for display, monitoring or further processing. A transmitter ensures that the measured values are provided to the user precisely and reliably. This component is often equipped with interfaces to transmit data in real time and enable integration into existing process control systems. Temperature and pressure compensation functions are also frequently integrated.
Types of flow meters
There are different types of flow meters, each developed for specific applications. Direct meters determine the flow rate through direct physical interaction with the medium, while indirect meters are based on physical principles such as ultrasound or vortex formation. The selection of the appropriate flowmeter depends on factors such as the medium, the desired accuracy and the specific process requirements. Each type offers unique advantages for different industrial requirements.
- Direct meters
Direct meters measure the flow of a medium by coming into direct contact with it. A commonly used type is the impeller meter, which is mounted directly in the flow pipe and measures the volume flow by measuring the rotational speed of an impeller. Direct meters offer the advantage of direct, immediate data that provides high accuracy, but material wear and pressure losses can affect performance.
- Impeller meter
Impeller meters are a type of direct flow meter in which a rotor or impeller rotates in the liquid flow. The rotational speed of the wheel is proportional to the flow rate, which enables precise measurements. These devices are ideal for clear liquids and are often used in water and wastewater systems. Their simple design makes them cost-effective, but they can become inaccurate due to high wear and viscosity influences.
- Oval gear meter
Oval gear meters are volumetric flow meters that are particularly suitable for viscous liquids. Two oval gear wheels rotate in each other and thus directly measure the volume flowing through. This design allows accurate measurement regardless of fluctuations in pressure and viscosity. Oval gear meters offer high precision and are popular in oil and chemical industry applications. Their robust design minimizes wear, but they require regular maintenance for optimum performance.
- Indirect meters
Indirect meters measure flow without direct contact with the medium. They use physical principles such as ultrasonic waves or pressure changes to determine the volume flow. These devices are suitable for applications where hygiene or minimal intervention in the process are crucial. Examples are ultrasonic meters and vortex flow meters. Indirect measuring devices offer high accuracy and flexibility, but are often more expensive than direct alternatives and require more complex calibration.
- Ultrasonic meters
Ultrasonic meters are indirect flow meters that use sound waves to determine the volume flow. They send and receive ultrasonic pulses, with the transit time or frequency shift determining the flow rate. This non-contact measurement method is ideal for hygiene-critical applications in the food and pharmaceutical industries. Ultrasonic meters offer high accuracy, but require clear liquids without particles and careful installation to ensure reliable results.
- Vortex flow meter
Vortex flow meters are indirect measuring devices that use the Kármán vortex street effect to measure flow. When a medium flows around a baffle, vortices are created behind this obstacle. The frequency of these vortices is proportional to the flow rate and is detected by sensors. Vortex flow meters are versatile, offer robust accuracy and are ideal for liquids and gases in the chemical and petrochemical industries.
Application and selection of flow meters
The right choice of flow meters depends on specific applications and process requirements. Different industries such as water treatment and food production require customized measuring solutions. Factors such as medium, temperature, pressure and required accuracy influence the choice of device. Users need to analyze the individual process conditions to select a suitable flow meter model that provides accurate results and efficient operation.
Application in various industries
Flow meters are widely used in various industries, from water treatment to food and beverage production. In the water treatment industry, they measure the volume flow to control water quality. In the food industry, they ensure precise dosing and mixing ratios, while in the chemical industry they monitor the safe transportation of gases and liquids. Each application requires specific devices to ensure optimum operation and product quality.
- Water treatment
In the water treatment industry, flow meters are essential for monitoring and controlling volume flows. They ensure precise measurements of the water flow through various treatment stages, whether for filtering, adding chemicals or pumping into distribution networks. Flow meters help to ensure water quality and make processes efficient. Accurate measurement of the flow rate is crucial in order to keep the pressure constant and energy consumption under control.
- Food and beverage industry
In the food and beverage industry, precise flow measurements are crucial for product quality and consistency. Flow meters monitor the exact quantities of liquids used in recipes and in the filling of products. They support compliance with strict hygiene regulations as many devices are contactless. The right choice of flow meters helps to increase efficiency, reduce waste and improve taste quality.
Criteria for choosing the right flow meter
Selecting the right flow meter requires consideration of several criteria: the type of medium (gas or liquid), process conditions such as temperature and pressure, required accuracy, installation size of the pipe and available budget. Additional requirements may include hygiene standards or potentially explosive environments. A detailed analysis of these factors helps users to choose the best flowmeter for their specific applications.
- Process conditions
Process conditions are crucial factors when selecting a flowmeter. These include temperature, pressure and viscosity of the medium as well as the size and material properties of the pipe. Knowledge of these parameters is essential to ensure the compatibility of the flow meter and to achieve optimum accuracy. Specific process requirements, such as aggressive media or high pressure fluctuations, influence the choice of devices and their long-term performance in industrial use.
- Aim of the measurement
The objective of the measurement is a key aspect when selecting a flow meter. Depending on the application, the main objective may be to monitor processes, ensure product quality or cost efficiency. Highest accuracy and reliability are required for exact billing, while robust and low-maintenance devices are often preferred in process circuits. Clearly defining the measurement objectives helps users to choose a device that efficiently meets the specific requirements.
Norms and standards in flow measurement
Norms and standards play a crucial role in flow measurement and ensure that devices meet requirements in terms of accuracy, safety and performance. They provide guidelines for calibration, installation and operation of flowmeters. European and international standards, such as ISO and EN, promote compatibility and quality in various industries, from food production to petrochemicals. Compliance with these standards ensures consistent and reliable measurements, which are essential for efficient process control.
- Relevant European directives
European directives are essential for the regulation of flow meters. The MID (Measuring Instruments Directive) specifies requirements for the accuracy and safety of measuring instruments for liquids and gases. The ATEX directive concerns devices used in potentially explosive atmospheres to ensure maximum safety. Compliance with these directives ensures that flowmeters meet the high standards of the EU, facilitating reliability and market access within Europe and providing confidence to users.
Safety and quality standards
Flowmeters must meet strict safety and quality standards to ensure reliable results and minimize potential risks in demanding industrial environments.
Product overview: Flow measurement and flow monitoring
For flow measurement and flow monitoring, we offer various devices and systems that are optimally adapted to different applications and process conditions. Below you will find an overview of our most important product categories:
- Flow monitoring of gases
Specialized devices that can reliably detect and quantify gases are suitable for the safe and precise monitoring of gas flows in industrial plants.
To the category Flow monitoring of gases
- Flow meters
Flow meters measure the volume flow of gases and liquids directly and continuously. Different measuring principles are used depending on the application.
To the flow meter category
- Volumetric flow measurement
Volumetric flow meters enable the precise determination of the flow rate of a medium and thus contribute to process optimization and resource conservation.
To the volume flow measurement category
- Flow monitoring with SIL classification
Special flow monitors with SIL (Safety Integrity Level) are used for the highest safety requirements, such as those required in the process industry.
To the category Flow monitoring with SIL classification
- Flow monitoring in potentially explosive atmospheres (ATEX)
For use in potentially explosive atmospheres, we offer devices in accordance with the ATEX directive that have been specially developed for increased safety requirements.
To the category ATEX flow monitors
- Flow monitoring accessories
Our comprehensive range of accessories rounds off the use of flow and flow monitors and enables flexible and safe installation and maintenance.
To category Flow monitoring accessories
FAQ - Frequently asked questions about flow measurement
Question: How does a flow meter work? Answer: A flow meter measures the volume or mass flow of a gas or liquid using various physical principles, depending on the type of device (mechanical, magnetic, ultrasonic, thermal, etc.).
Question: How accurate are modern flow meters? Answer: High-quality models achieve measuring accuracies of less than 1% of the measuring range, depending on the measuring principle, medium and installation conditions.
Question: Where are flow meters used? Answer: Typical areas of application are water treatment, food industry, chemical and pharmaceutical industry, energy sector and plant engineering.
Question: What must be considered when selecting a flow meter?
Answer: The medium, temperature, required accuracy, installation conditions, standards and budget are important.
Question: Which standards apply to flow measurement? Answer: The most important standards are ISO, EN, MID (Measuring Instruments Directive), ATEX (for potentially explosive atmospheres) and industry-specific hygiene standards.