Ultrasonic Flow Meter


Welcome to Coltraco Ultrasonics’ range of Ultrasonic Flow Meters. 

We pride ourselves with the quality, reliability and accuracy of our instruments – all made in the UK. 

Our Ultrasonic Flow Meter range has been tested and calibrated at an ISO 17025 laboratory, meeting accuracies of +/- 0.5% of the true flow rate. 

Using non-invasive technology, our transit time flow meters have significant advantages against an inline flow meter by reducing installation cost, risk and downtime for your flow rate measurements.  

Portasonic® PLUS is a portable ultrasonic transit-time flow meter designed to measure, internally record, and export the flow rate within a pipe with precision and ease. Portasonic® PLUS uses a customisable pre-programmed database to allow it to work with a wide variety of pipe materials and liquid types as a highly versatile monitoring solution that can be adapted for specific applications.

P/N: 2618949-PSOPLUS


The Permaflow® is a fixed, clamp-on, ultrasonic transit time flow and heat meter that is non-invasive for measuring the flow rates of liquids containing less than 10% of gas/solid contents. It is mains powered, designed for 24/7 monitoring and is accurate to +/- 0.5% of measured value under ideal conditions.

P/N: 3578010-FLOW

Calculate internal pipe pressures using externalnon-invasive and portable flow sensors. To be used alongside the Portasonic 2.FLO® portable ultrasonic flow meter 

P/N: 2618949-CALC


The Portasonic® PRO is a handheld tablet-based ultrasonic clamp-on flow meter with pressure prediction software for calculating internal pipe pressure from measured flow rates. It combines the functionality of the Portasonic® 2.FL0 in measuring flow rates non-invasively with the Portasonic® CALCULATOR, to form the first instrument capable of calculating the internal pressure within pipes, using non-invasive, externally measured flow sensors.

P/N: 2618949-PSOPRO

What is an Ultrasonic Flow Meter?

Ultrasonic flow meters are non-invasive flow-measuring devices that use sound waves to determine the flow rate of liquids and gases. These meters are becoming increasingly popular due to their high accuracy, low maintenance requirements, and versatility. They can be used in various applications, including industrial processes, water treatment, and energy management.


Working Principle of Ultrasonic Flow Meters

The working principle of ultrasonic flow meters is based on measuring the transit time of sound waves through a fluid. Ultrasonic flow meters use high-frequency sound waves to determine the flow rate of a liquid or gas. The sound waves are sent through the fluid in the direction of the flow, and the time taken for the waves to travel from one point to another is measured. The flow rate can then be calculated based on the difference in transit time between the two points.

There are two main types of ultrasonic flow meters: transit-time and Doppler. Transit-time ultrasonic flow meters measure the difference in transit time between sound waves travelling with and against the flow. In this type of meter, two transducers are installed on opposite sides of the pipe, one sends a sound wave through the fluid in the direction of the flow, and the other receives it. The transit time is then calculated by comparing the time the wave travels from the first transducer to the second transducer with and against the flow.

Doppler ultrasonic flow meters, on the other hand, measure the frequency shift of sound waves reflected off of moving particles in the fluid. In this type of meter, a single transducer sends a sound wave into the fluid, and the frequency shift of the wave is measured as it is reflected off of moving particles in the fluid. The flow rate can then be calculated based on the frequency shift of the reflected wave.

Transit-time and Doppler ultrasonic flow meters offer high accuracy and versatility, making them suitable for various applications. However, the choice between the two types of meters will depend on the specific requirements of the application, including the type of fluid being measured, the flow rate, and the conditions of the measuring environment.


Why choose Coltraco Ultrasonics’ range of Ultrasonic Flow Meters?

  1. Accuracy and reliability proved at an ISO 17025-certified laboratory for flow measurement devices in the UK

  2. We strive to offer the highest quality instruments, built with exceptional quality materials in the UK and remain competitively priced in the market worldwide through our unique R&D position
  3. Our ultrasonic flow sensors are made using a special composite material to optimise ultrasound transmission
  4. All units come with a built-in oscilloscope for signal diagnostics that assist you in performing a reliable measurement as part of the setting up process
  5. Modular I/O options for the Permaflow® system which allow you to choose only what you need, saving cost and money
  6. Integrated ultrasonic thickness gauge on the Portasonic® PLUS which allows you to perform simple NDT testing (ultrasonic thickness gauging) on the wall thickness of your pipe to determine wall thickness and look for signs of corrosion
  7. Technical support and advice are available throughout the lifetime of the unit and we are here to help you with your application

Transit Time Ultrasonic Flow Meter Operating Principle

The Portasonic®  and Permaflow®  range of ultrasonic flow meter works on the transit-time principle. The principle of flow measurement using ultrasonic clamp-on transit time measurement is simple and can be illustrated in the figure below.

ultrasonic flow meter drawing
Flow velocity drawing

Two ultrasonic sensors are clamped to the outside of the pipe at a pre-determined distance apart. The ultrasonic signal travels between the transmitters through the pipe wall and the fluid within the pipe. If the fluid is flowing, then it takes slightly longer for the ultrasound to travel against the flow (upstream time T_up) than with the flow (downstream time T_down).

In a typical installation, the individual times measured upstream and downstream are just a few hundred microseconds, the difference between them is typically measured in tens of nanoseconds.

This very small time difference (T_up – T_down) is measured by the flowmeter and is directly proportional to the flow velocity (V) of the fluid.

Doppler Ultrasonic Flow Meter Operating Principle

Ultrasonic flow meters use a single ultrasonic transducer that emits high-frequency sound waves into the fluid. The sound waves reflect off the particles or bubbles in the fluid and create a frequency shift known as the Doppler shift. The change in frequency is proportional to the fluid velocity. By measuring the Doppler shift, the flow velocity and volume can be calculated.

Types of Flow Measured by Portasonic® PLUS and Permaflow®

Volumetric Flow Rate: Knowing the pipe’s internal cross-sectional area the ultrasonic flow meter can calculate the volume flow rate in many common engineering units such as litres per hour (l/h), gallons per minute (gpm) etc. This gives a similar measurement unit to that given by a vortex flow meter, variable area flow meter, differential pressure flow meter or another inline flow meter.

Mass Flow Rate: Incorporating the density of the fluid allows the ultrasonic meters to calculate the mass flow rate. This gives a similar measurement unit to that given by mass flow meters or Coriolis meter.

Heat or Energy Flow Rate: A knowledge of inlet and outlet fluid temperature and the Specific heat Capacity of the fluid allows the flow meter to calculate the heat flow rate. This is suitable for energy efficiency calculations for heating and chilling applications.

Totalised Flow: Both the Portasonic® PLUS and Permaflow® come with a flow totalizer function. The flow totalizer totalises (adds up) the volume of fluid that has flowed through the pipe. The totalizer function allows these rates (Volumetric Flow Rate, Mass Flow Rate, Heat or Energy Flow Rate) to be totalled and positive, negative and net values can be displayed.

Key Transit Time Flow Meters Installation Considerations

  1. Ensure the pipe is full of fluid and that air bubbles in the fluid are minimised to ensure the ultrasound signal transmits effectively
  2. Ensure the sufficient distance between the ultrasonic sensors and the nearest bend or valve in the pipework to minimise turbulence
  3. Ensure the fluid has less than 10% solids content, if the fluid exceeds this limit then a Doppler flow meter may be more suitable

Advantages of an Ultrasonic Flow Meter against an Inline Flow Meter

  1. No installation costs such as drilling into pipes, therefore no downtime to the pipe network is present
  2. As there is no contact with the fluid being measured, there is no risk of pressure drop throughout your pipe network
  3. As the fluid cannot damage the flowmeter, this could contribute to a longer lifespan and lower maintenance cost compared to inline flow meters which are in contact with the fluid and risk being damaged by the pressurised flowing fluid

The Importance of Calibration in Flow Meters

Performing calibration of flow meters is the only way to ensure the flow measurement performed by your ultrasonic flowmeter is accurate. Calibrated flow meters operate to give you the confidence that your ultrasonic flight flow meters will produce a reliable measurement.

At Coltraco Ultrasonics, our ultrasonic flow meter range has been tested and accuracy proven at an ISO 17025-certified laboratory for flow measurement in the UK.

Using a non-invasive ultrasonic flow meter to determine the pressure

Coltraco Ultrasonics has developed the Portasonic® Calculator, the first instrument capable of determining the internal pressure within pipes, using non-invasive, external flow measurement technology.

This Portasonic® Calculator is designed to operate alongside our Portasonic® PLUS Ultrasonic Flow Meter. The Portasonic is one of the world’s leading non-invasive flow meters and is an essential tool for a wide variety of maintenance and inspection needs

The Portasonic® Calculator is designed as a supporting instrument and uses an empirical equation derived from the laws of fluid dynamics to calculate the liquid pressure to within 5% accuracy.

Our knowledge of the properties of 19+ different fluids and 23 different common pipe materials has enabled us to understand the pressure required to drive different fluids at various flow speeds.

Suitability of an ultrasonic flow meter for water flow metering

Water meters are used all throughout domestic and commercial environments to track water usage. Transit time ultrasonic flow meters can perform accurate and reliable water measurements in pipes. While water meter users typically go for low-cost instruments, ultrasonic flow meters are the most appropriate solution for situations where the pipe cannot be drilled into or if the flow of water cannot be interrupted while the water meter is being fitted. The non-invasive principle of a transit time ultrasonic flow clamp on a meter is highly beneficial for such situations whereby an inline flow meter cannot be used. Water is one of the easiest liquids to measure due to its physical and chemical properties and you should have no problems with using ultrasonic flowmeters as water meters.

Why Choose an Ultrasonic Flow Meter?

Ultrasonic flow meters offer several advantages over other types of flow measurement instruments, including:

  1. Non-intrusive: Ultrasonic flow meters do not require any contact with the fluid, which means they do not have any pressure drop or obstruction in the flow path. This leads to less maintenance and less downtime.
  2. Accurate: Ultrasonic flow meters can measure flow rates with high accuracy and repeatability. They can handle a wide range of flow rates and fluid types.
  3. Versatile: Ultrasonic flow meters can be used for both liquids and gases. They can measure flow rates in both directions and be used for custody transfer and process control applications.
  4. Cost-effective: Ultrasonic flow meters are cost-effective compared to other flow measurement instruments, such as Coriolis and thermal mass flow meters.

Receive Expert Advice and Guidance on Ultrasonic Flow Meters, and Get in Touch with Coltraco Ultrasonics.

In summary, Ultrasonic Flow Meters are a reliable and accurate technology for measuring flow rates in various industrial processes. Their non-invasive nature eliminates the need for moving parts, ensuring their durability and longevity. Ultrasonic Flow Meters can handle different fluids and work well in extreme temperatures and pressures.

Nevertheless, it is crucial to be aware of the limitations of Ultrasonic Flow Meters when selecting this technology. These flow meters require a clear and unobstructed path for the sound waves to travel, making them unsuitable for use in pipelines with built-in obstructions or fluids containing high amounts of suspended solids. Additionally, some models may not accurately measure flow rates below a certain threshold or very low flow rates.

When considering Ultrasonic Flow Meters for a particular application, it’s essential to weigh the specific requirements of the application against the technology’s limitations to make an informed decision.

If you need more information or guidance, contact Coltraco Ultrasonics’ team of experts.

Portasonic® PLUS and Permaflow® Technology Comparison

Ultrasonic Flow Meter Frequently Asked Questions

Is the ultrasonic technology used in Portasonic® PLUS and Permaflow® similar to the ultrasonic technology used for natural gas flow metering and flow meter for gas?

The ultrasonic technology used in flow meters for gas or flow meters for air is not applicable to our range of ultrasonic flowmeters. Our ultrasonic flow meters are designed for the flow measurement of fluids.

In ultrasonic flow meter technology, what are the main differences between transit time flow meters and Doppler flow meters in measuring volume flow rate?

Transit time flow meters use two clamp-on ultrasonic sensors spaced at a pre-determined distance, one as an ultrasonic transmitter and another as an ultrasonic receiver. The ultrasonic signal travels between the ultrasonic sensors through the pipe wall and the fluid within the pipe. If the fluid is flowing, it takes slightly longer for the ultrasound to travel against the flow than with the flow. The time difference between upstream and downstream is measured and is directly proportional to the fluid velocity.

Doppler flow meters, on the other hand, rely on bubbles and particles in fluids which are suspended to reflect the ultrasonic signal that provides a shift in the frequency. The shift in frequency is directly linked to the velocity of the travelling fluid. By measuring the frequency shift between the ultrasonic transmitter, receiver and fluid carrier (i.e. bubbles and particles), the fluid velocity is determined.

What are the main differences between an ultrasonic flow meter and a mechanical flow meter?

A mechanical flow meter is an inline flow meter. Examples are positive displacement flowmeters (PD meters) and turbine flow meters. An ultrasonic flow meter uses clamps on ultrasonic sensors which are non-invasive. Mechanical flow meters are typically built for a specific range of pipe sizes, and cannot be retrofitted into other pipe sizes whereas an ultrasonic flow meter works over a broad range of pipe sizes as it is non-invasive. The pressure of the pipework also has to be taken into account for a mechanical flow meter as this can damage the mechanical flow meter whereas this is not a point of concern for ultrasonic flow meters which are external, non-invasive and clamped on the pipe.

How do the Portasonic® PLUS and Permaflow® compare against inline flow meters for measuring mass flow?

An example of an inline flow meter for measuring mass flow is a Coriolis meter. The Coriolis flow meter is an invasive flow meter that requires breaking into the pipe during installation. The mass flow measurement from a Coriolis meter is very reliable, however, the ultrasonic flow meter is capable of matching the mass flow measurement accuracy of the Coriolis meter under certain conditions. If you are looking for a non-invasive solution to measure mass flow, the Portasonic® PLUS can assist with its clamp-on ultrasonic transmitters that is capable of measuring mass flow.

Can we distinguish between a rotameter and an ultrasonic flow meter?

A rotameter is a form of a variable area flow meter. It is a form of inline flow meter and is commonly used in different applications to ultrasonic flow meters.

How does an ultrasonic flow meter work?

An ultrasonic flow meter operates based on the principle of measuring the time it takes for an ultrasonic signal to travel between two points in a fluid. It consists of transducers that emit and receive ultrasonic signals. The flow meter sends ultrasonic signals through the fluid, and the signals are reflected back to the receiving transducer. By comparing the time taken for the signals to travel upstream and downstream, the flow meter calculates the velocity of the fluid and determines the flow rate.

What is the main advantage of an ultrasonic flow meter?

The main advantage of an ultrasonic flow meter is its non-intrusive nature. It does not require physical contact with the fluid, eliminating the need for cutting pipes or disrupting the flow. This non-intrusive design results in minimal pressure drop, reduced maintenance, and improved efficiency. Additionally, ultrasonic flow meters can measure a wide range of fluids, including clean liquids, slurries, and even gases.

Are ultrasonic flow meters accurate?

Yes, ultrasonic flow meters are known for their high accuracy. When properly installed and calibrated, they can provide precise flow measurements across a wide range of flow rates. Accuracy can be affected by factors such as fluid properties, pipe conditions, and installation quality. Regular maintenance, including cleaning of transducers and verification of calibration, is necessary to ensure continued accuracy.

What is the difference between an ultrasonic and magnetic flow meter?

The main difference between an ultrasonic flow meter and a magnetic flow meter lies in their operating principles. While an ultrasonic flow meter relies on ultrasonic signals to measure flow, a magnetic flow meter utilizes Faraday’s law of electromagnetic induction. Ultrasonic flow meters are suitable for a wide range of fluids and offer non-intrusive installation, while magnetic flow meters excel in measuring conductive fluids and require a conductive medium for operation.

What is the difference between sonar and an ultrasonic flow meter?

Sonar and ultrasonic flow meters differ in their applications and operating principles. Sonar is primarily used for underwater distance measurement and object detection using sound waves. On the other hand, an ultrasonic flow meter is specifically designed to measure fluid flow rates in pipes. Ultrasonic flow meters employ transducers that emit and receive ultrasonic signals, allowing them to calculate flow velocities and determine flow rates.

How is flow measured in an ultrasonic flow meter?

Flow is measured in an ultrasonic flow meter by analyzing the time it takes for ultrasonic signals to travel between transducers. By measuring the time difference between upstream and downstream signals, the flow meter can calculate the velocity of the fluid. The flow rate is then determined by multiplying the fluid velocity by the cross-sectional area of the pipe.

Can an ultrasonic flow meter measure air flow?

Generally, ultrasonic flow meters are designed for measuring the flow of liquids rather than air. Ultrasonic flow meters rely on the propagation of ultrasonic signals through a fluid medium, and the properties of air (being a compressible gas) make it challenging to obtain accurate measurements using ultrasonic technology. For air flow measurement, other techniques such as thermal mass flow meters or anemometers are more commonly used.

What diameter should an ultrasonic flow meter be?

The diameter of an ultrasonic flow meter depends on the pipe size or the diameter of the pipe through which the fluid flows. Ultrasonic flow meters are available in various sizes to accommodate different pipe diameters. It is important to select a flow meter that matches or is compatible with the pipe diameter to ensure accurate and reliable measurements.

How do you install an ultrasonic flow meter?

Installing an ultrasonic flow meter typically involves the following steps:

Select an appropriate location: Choose a suitable location on the pipe where the flow meter can be securely installed. Consider factors such as pipe accessibility, straight pipe lengths, and the absence of obstructions.

Prepare the pipe: Clean the pipe surfaces to ensure proper adhesion of transducers and remove any debris or contaminants that may interfere with the measurements.

Mount the transducers: Attach the transducers to the pipe using clamps or adhesive coupling. Follow the manufacturer’s instructions for proper alignment and positioning.

Connect the cables: Connect the cables from the transducers to the flow meter’s electronics module or control unit.

Configure and test: Configure the flow meter settings according to the specific application requirements. Perform a thorough testing and verification process to ensure accurate measurements.

It is recommended to refer to the manufacturer’s installation guidelines and user manual for detailed instructions specific to the ultrasonic flow meter model you are working with.

Is an ultrasonic flow meter bidirectional?

Yes, many ultrasonic flow meters are bidirectional, meaning they can measure flow in both directions (forward and reverse). This capability is particularly useful in applications where flow direction changes or when it is necessary to monitor flow in both directions. However, it is important to check the specifications of the specific ultrasonic flow meter model to ensure bidirectional flow measurement capability.

What are the applications of an ultrasonic flow meter?

Ultrasonic flow meters find applications in various industries and fluid handling systems, including:

    • Water and wastewater management
    • Oil and gas industry
    • Chemical and petrochemical processes
    • HVAC (Heating, Ventilation, and Air Conditioning)
    • Power generation plants
    • Pharmaceutical manufacturing
    • Food and beverage processing
    • Mining and mineral processing
    • Agriculture and irrigation systems

These flow meters are suitable for a wide range of liquids, such as water, fuels, oils, chemicals, and various process fluids.

Do ultrasonic sensors work in the dark?

Ultrasonic sensors do not rely on visible light and can operate in darkness. They use sound waves that are outside the range of human hearing. The absence of light does not affect the performance or functionality of ultrasonic sensors, making them suitable for applications in low-light or dark environments.

How do I know if my flow meter is accurate?

To verify the accuracy of a flow meter, you can follow these steps:

Reference Standards: Compare the measurements obtained from the flow meter with a known reference standard, such as a calibrated flow meter or a flow measurement device of high accuracy.

Calibration: Periodically calibrate the flow meter according to the manufacturer’s recommendations and industry standards. Calibration ensures that the flow meter provides accurate measurements over time.

Verification Tests: Conduct verification tests by using different flow rates and conditions to check the flow meter’s performance. Compare the measurements obtained by the flow meter with expected or theoretical values.

Regular Maintenance: Proper maintenance of the flow meter, including cleaning, inspection, and ensuring the integrity of transducers or sensors, helps maintain accuracy.

If you have concerns about the accuracy of your flow meter, consult the manufacturer or engage with a qualified calibration service provider to assess and verify its accuracy.

Can ultrasonic waves go through walls?

Ultrasonic waves have difficulty passing through solid objects like walls, especially those made of dense materials. Solid objects tend to reflect or absorb the ultrasonic waves, limiting their transmission through the wall. However, certain types of ultrasonic waves, such as low-frequency or long-range ultrasonic waves, may have better penetration capabilities through walls compared to high-frequency waves. The ability of ultrasonic waves to go through walls depends on the wall material, thickness, frequency of the waves, and the specific characteristics of the ultrasonic system being used.