Non-Intrusive, Clamp-on Ultrasonic Technologies
Emerson’s Flexim ultrasonic flow measurement technology measures liquids, gases, and steam without intrusion. Its clamp-on ultrasonic flow meters attach easily to the pipe’s exterior, requiring no operational interruptions or leak risks. Designed for industrial production and safety, these meters ensure maximum plant availability and reliable performance.
Products
Measurement Principles
Ultrasonic flow meters transmit sound waves and measure the time they take to return. Clamp-on systems use the transit-time difference method, detecting delays caused by fluid flow inside the pipe. This delay is accurately measured, and the transmitter calculates flow rate using pipe and fluid data. The FLUXUS® series delivers top performance in demanding applications.
Proven Accuracy
Reliability and accuracy depend on quality manufacturing and calibration. Flexim ensures consistent quality with DIN ISO 9001 and a calibration lab certified to DIN EN ISO/IEC 17025:2018. It uniquely calibrates transmitters and sensors independently using its patented AperCal method. This calibration, traceable to national standards, avoids uncertainties by not relying on flow rigs or pipe conditions.
Non-Intrusive Ultrasonic
The Flexim FLUXUS® non-intrusive ultrasonic flow meters measure virtually any fluid—liquid, gas, or steam—using clamp-on technology. They work bi-directionally across a wide range. This reliable, external method has become standard in many industries due to its versatility and practical advantages for flow measurement.
Diagnostic Insight: Advanced Meter Verification
Advanced Meter Verification (AMV) lets you check your Flexim flow meter’s health on site without interrupting processes, saving costs and ensuring performance. The transmitter continuously stores diagnostic data for regular verification. This helps plan maintenance, prevent failures, and allows automatic generation of verification reports for quality management documentation.
On-Site Measurement Services
Let our experienced technicians handle your flow measuring tasks on-site, saving you time and resources. Our services are tailored to your needs, covering volumetric and mass flow of liquids and gases, energy surveys for heat, cold, and compressed air, and flow measurements on pipes up to 1166 °F (630 °C). We also offer lab analysis, project support, training, rentals, and consulting.
Applications
Gas Applications
The FLUXUS® G gas flow meter series from Emerson Flexim sets the standard for non-intrusive ultrasonic gas metering. Clamped outside the pipe, these bi-directional meters measure any gas and come in portable and stationary types. With pressure and temperature integration, they deliver precise mass and volumetric flow rates. Ideal for hazardous gases, including explosive, toxic, or aggressive types.
Liquid Applications
Flexim FLUXUS® F ultrasonic liquid flow meters measure liquid flow non-intrusively with transducers mounted outside the pipe. Available in portable and stationary types, they handle water, low flow rates, extreme temperatures, explosive areas, and underwater use. Emerson Flexim uniquely offers SIL2-certified clamp-on ultrasonic transducers for safety-critical applications.
Steam Applications
Emerson Flexim leads in non-intrusive steam flow measurement with clamp-on ultrasonic technology. FLUXUS® ST-LT measures volumetric and mass flow of steam up to 180 °C (356 °F) and is available portable or stationary. The stationary ST-HT handles temperatures above 240 °C (464 °F), reaching up to 630 °C (1,166 °F) with the WaveInjector® mounting fixture.
Compressed Air
Accurate compressed air flow measurement improves energy efficiency and reduces costs. The non-intrusive FLUXUS® CA ultrasonic air flow meters, available as permanent or portable solutions, are ideal for energy audits, consumption metering, meter verification, leak detection, network balancing, and monitoring compressor efficiency.
Thermal Energy
Based on Flexim's clamp-on technology, FLUXUS® TE combines volumetric flow and energy calculation in one transmitter. With up to 2 flow channels and 4 temperature inputs, it measures flow rates, thermal energy, temperatures, and counters. It’s ideal for applications like heating and cooling, offering efficient, accurate energy monitoring.
Extreme Temperatures
The Flexim WaveInjector® technology is used in extreme temperatures. The patented transducer mounting device separates the ultrasonic transducers thermally from the pipe thereby extending the application range of non-intrusive clamp-on ultrasonic technology to temperatures of -200 to 630 °C (-328 to 1166 °F). So much heat is radiated or absorbed via its metallic coupling plates that the temperature of the transducer clamping fixture lies within the working range of the ultrasonic transducers. The WaveInjector® is also mounted on the outside of the pipe without having to open the pipeline. Since it is a purely mechanical arrangement, the WaveInjector® can also be used in potentially explosive areas.
Process Analytics
Emerson Flexim mass flow meters measure the flow velocity, and they use the sound speed to determine concentration or density of binary liquid solutions. Combining both flow and density the PIOX S provides a mass flow rate reading. Typical applications are sulfuric and hydrochloric acid, caustics, brines, and nitrogen fertilizer products. The clamp-on technology with no wetted parts is ideal for analyzing challenging fluids. When only density and concentration measurements are required, Flexim offers the PIOX® R inline process refractometer. It combines the long-established concept of the concentration meter with the innovative transmitted light principle. This unique technology provides online concentration with outstanding precision. Both systems can also be used in combination, to analyze more complex media in customer specific applications.
Industries
Oil & Gas
Oil & Gas production, transportation, and storage operations are subject to the highest and most complex process conditions and to strict standards of performance, availability, and efficiency. Accurate, reliable, and cost-effective clamp-on oil and gas flow meters are specifically designed to withstand the extreme processes and ever-changing conditions of the industry. Our non-intrusive, clamp-on ultrasonic flow meters are the perfect solution for high pressures, high temperatures, abrasive fluids, and safety requirements across the industry.
Chemical
The operational conditions within chemical sites are very demanding. A wide range of organic and inorganic fluids are handled, some of which are flammable, toxic, or highly corrosive. Furthermore, extreme temperature ranges can be encountered. It is under these challenging conditions that the outstanding advantages of ultrasonic flow meters and concentration meters become most apparent. They are maintenance-free and offer excellent accuracy and repeatability.
Food & Beverage
The strict requirements of the food & beverage industry for hygienic design, measuring performance and accuracy are easily met by Emerson Flexim flow meters. With the use of the sanitary FLUXUS® flow measurement systems, the risk of contaminating pure fluids or creating problematic hygienic “dead spots” within a product line is excluded. 100% hygienic and 100% contamination free.
Water
Our range of water flow meters are useful in a wide range of applications across multiple industries, including potable water treatment, wastewater treatment and metering for water distribution. Our clamp-on ultrasonic water flow meters can be installed without any service interruption or pipework alterations. Because they make no contact with the water itself, these ultrasonic water flow meters are a hygienic solution, and they cause no wear to pipes and other components.
Power
Modernization is essential for driving efficient power generation. Non-intrusive instrumentation for steam flow measurement in power plants and other applications means no interruption in supply and no direct contact with the process fluids. This makes our energy consumption measurement solution also free of maintenance and helps power plant operators to monitor and control their processes with the highest efficiency and outstanding flexibility.
Mining
The mining industry faces some of the harshest industrial environments. Accurate, reliable and durable flow monitoring is crucial to maintain well balanced and optimized minerals processing. The flowing fluids, most often abrasive mineral slurries, corrosive leach solutions or toxic chemicals, cannot damage or wear the non-intrusive Flexim transducers.
Pulp & Paper
Wood is the most important raw material in industrial paper production. The main processes involve the processing of wood chips and the subsequent pulp production. When it comes to guaranteeing consistent paper quality, the right mixture is key. This is where Flexim’s flow and concentration measuring technologies come into play, especially in difficult applications when measuring the highly corrosive liquors or the flow of slightly adhesive substances like glue and paste or highly abrasive slurries and pulps.
HVAC Systems
Easy to retrofit and reliable thermal energy flow measurement devices, Flexim flow meters for chilled water and hot water are an ideal technology for today’s energy management, submetering and monitoring measuring tasks. Hot water and chilled water flow meters serve an important function in maintaining an efficient system.
Aviation
Check and monitor the functionality and internal leak rate of the green, yellow and blue hydraulic systems for the complete, left-hand wing, right-hand wing and tail sections of the aircraft without the need for any direct works on the hydraulic lines. These hydraulic oil flow meters are clamped directly to the hydraulics line. The use of ultrasonics enables these hydraulic flow meters to do their job without lengthy installation times or creating obstructions on the line. Their non-intrusive nature and accuracy make them some of the most important hydraulic measuring instruments available today.
Resources
Strong Customer Focus
Flexim manufactures high-quality measurement instruments and offers technical and consulting services. We offer on-site measurements, lab analysis, project handling, training, commissioning, rentals, and expert consulting.
The FLUXUS ultrasonic systems measure the flow rate using the transit time difference method. Clamp-on ultrasonic sensors mounted on the outside of the pipe alternately send and receive signals in and against the direction of flow in the pipe. As the fluid in which the signals spread flows, the signals are carried along with it. This movement causes a shortening of the sound path for the signal in the direction of flow and a lengthening for the signal against the direction of flow. As a result, the transit times also change. The transit time of the signal in the direction of flow is shorter than that in the opposite direction. The transit time difference is proportional to the average flow velocity. Based on this, the measuring transducer calculates the volume flow by processing the pipe cross-section and the mechanical fluid parameters.
The measurement of the transit time difference is a pure time measurement. This can be realized with extreme accuracy. The uncertainty of our FLUXUS flow meters for the measured volume flow is typically 1% of the measured value, while the repeatability, which is crucial in many applications, is 0.15%.
With the FluxDiag software, Emerson | Flexim offers powerful software to precisely determine the uncertainty at the measuring point and to evaluate the measurement quality.
Emerson | Flexim is the only manufacturer of ultrasonic flow meters that calibrates transmitters and sensor pairs independently of each other and traceable to national standards. Only by doing so is it ensured that the specified measurement uncertainty is reliably maintained regardless of the combination of transducer and sensors.
In principle, yes. The only requirement for the functioning of flow measurement with externally mounted clamp-on ultrasonic sensors is that both the pipe wall and the medium flowing inside can be penetrated acoustically, i.e. measurement on partially filled pipes is not possible (or does not provide reliable measurement results). The ultrasonic sensors for liquids offered by Emerson | Flexim cover a pipe size range (internal diameter) from 0.24 to 256 in (6 mm to 6.5 m).
The powerful transmitters of the FLUXUS series as well as the broad sensor portfolio with both shear wave and Lamb wave sensors enable non-intrusive flow measurement even on challenging composite pipe materials such as PCCP and also on liquids with high solid or gas content. One of the main advantages of non-intrusive measurement technology in such challenging applications is that the feasibility can be checked directly on site without any disruption to plant operation.
No. A key feature of ultrasonic flow measurement technology is its extreme measurement dynamics. FLUXUS measures highly accurate flow velocities from 0.39 in/s to 82 ft/s (0.01 to 25 m/s) regardless of the flow direction, i.e. the measurement is bidirectional. Cross-sectional tapering, which may be necessary for wetted measurement methods that require a minimum flow, is no longer necessary.
No, FLUXUS can do much more. The primary variable measured by the FLUXUS flow meter is the difference in signal transit time in and against the direction of flow. This is a metric for the average flow velocity. The measuring transducer uses this to calculate the volume flow.
If the pressure and temperature - and therefore the density of the fluid - are constant in the process, the transmitter can also output the mass flow. If pressure and temperature change, these must be measured and fed into the transmitter via current inputs. FLUXUS then determines the mass flow from the volume flow and density non-intrusively.
FLUXUS can also determine the heat flow in heat transfer processes. For this purpose, the temperature only needs to be recorded in the flow and return. The heat flow meters from Emerson | Flexim are called FLUXUS F TE.
Using the same measurement technology as for flow measurement - i.e. the clamp-on ultrasonic sensors mounted on the pipe - FLUXUS also simultaneously measures the sonic velocity in the fluid. This is a material-specific variable. Therefore, non-intrusive acoustic measurement technology is also suitable for process analysis purposes, such as media differentiation and media determination. The clamp-on ultrasonic analytical systems from Emerson | Flexim are called PIOX S.
No. Because the sensors do not come into direct contact with the medium, they are practically not subject to wear. Permanently stable coupling foils ensure the best acoustic coupling over the long term. For measuring tasks where accuracy is particularly important, Emerson | Flexim recommends regular checking of the measurement at 5-year intervals and possibly recalibration. The check can be carried out by our experienced service technicians on your premises.