Showing posts with label Flexim. Show all posts
Showing posts with label Flexim. Show all posts

Thursday, December 28, 2017

Measurement and Calibration Principle of FLEXIM's Non-Invasive Ultrasonic Flowmeter

The principle of FLEXIM's ultrasonic flow measurement of liquids and gases relies on the propagation of ultrasonic wave signals into the medium. This measurement method exploits the fact that the transmission speed of an ultrasonic signal depends on the flow velocity of the carrier medium. Similar to a swimmer swimming against the current, an ultrasonic signal moves slower against the flow direction of the medium than when in flow direction.

For the measurement, two ultrasonic pulses are sent through the medium, one in the flow direction, and a second one against it. The transducers are alternatively working as an emitter and a receiver. The transit-time of the ultrasonic signal propagating in the flow direction is shorter than the transit-time of the signal propagating against the flow direction. A transit-time difference, Δt, can thus be measured and allows the determination of the average flow velocity based on the propagation path of the ultrasonic signals. An additional profile correction is performed by our proprietary algorithms, to obtain an exceptional accuracy on the average flow velocity on the cross-section of the pipe - which is proportional to the volume flow, and when temperature and pressure compensated, to the mass flow.

Since ultrasounds propagate in solids, the transducers can be mounted onto the pipe. The measurement is therefore non-invasive, and thus no cutting or welding of pipes is required for the installation of the transducers.

For more information about FLEXIM, contact Flow-Tech at 410-666-3200 or visit

Saturday, November 11, 2017

Clamp-on, Transit-time Difference Ultrasonic Flowmeters Ideal for HVAC Retrofit and New Construction

Transit-time Difference Ultrasonic Flowmeters
Transit-time Difference Ultrasonic Flowmeters (Flexim)
There are many reasons for large commercial buildings, medical centers, museums, airports, sports complexes, federal institutions and military complexes to invest in building energy optimization efforts. Better and more efficient operation of HVAC equipment can reduce the buildings energy and operational costs significantly.

Controlling flow, temperature and pumps can provide energy cost savings of over 20%. Many campus energy managers believe that the biggest user of energy in any complex is the HVAC system, and the key to saving energy in HVAC systems is an accurate and reliable flow metering capability.

Better efficiency of the heating and cooling infrastructure of a building also leads to more environmentally friendly buildings, something that has become a social prerogative of building owners and operators.  Older buildings were not built with BTU meters as metering requirements were added to buildings through increased regulations.

Submetering the buildings heating and cooling systems have become increasingly more important, as building owners are both mandated to meter these utilities and have a financial interest in the accuracy of these BTU measurements. The problem historically is that nearly all flow meters are designed for gradual failure due to direct contact with the fluids they are monitoring and the particulate accumulation on the sensors.

Clamp-on, transit-time difference ultrasonic flowmeters are the ideal retro-fit flowmeter, and also should receive strong consideration for new building construction. Transit-time difference ultrasonic clamp on flowmeters exploit the fact that the transmission speed of an ultrasonic signal depends on the flow velocity of the carrier medium - kind of like a swimmer swimming against the current. The signal moves slower against the flow than with it.

How Transit-time Difference Ultrasonic Flowmeters Work

The flowmeter sends ultrasonic pulses through the process medium - one in the same direction as the
flow and one in the opposite direction. The flowmeter's transducers alternate as emitters and receivers. The transit time of the signal going with the flow is shorter than the one going against. The flowmeter measures transit-time difference and determines the average flow velocity of the process medium. Since ultrasonic signals propagate in solids, the flowmeter can be conveniently mounted directly on the pipe and measure flow non-invasively.

Contact Flow-Tech with your questions about any flow measurement application. Reach them at 410-666-3200, or visit

Sunday, April 30, 2017

Understanding Ultrasonic Flow Measurement

externally mounted flow meters
Externally mounted (clamp-on) flow meters (Flexim)
Ultrasonic flow meters measure, via sound waves inaudible to humans, the velocity of fluid flowing through a conduit. The conduit can be a recognizable closed piping run, or open channels, flumes, or chutes. The technology is predominantly applied to liquids and gases.

There are three types of ultrasonic flow meters, differentiated by their means of measurement. An open channel flow meter derives liquid depth by computing geometrical distance, combining it with a velocity measurement and known dimensional properties of a flume or other channel. A Doppler shift flow meter reflects ultrasonic energy off sonically reflective materials and measures the frequency shift between emission and reflection to derive a fluid velocity measurement. The contrapropogating transit-time flow meter, more recognizably, the transmission flow meter. The transmission flow meter has two versions: the in-line and the clamp-on. The in-line configuration is intrusive, with flow meter hardware extending into and exposed to the measured media. A clamp-on style ultrasonic flow meter resides on the outside of the pipe, emitting and receiving the ultrasonic pulses through the pipe wall. These process measurement tools, using ultrasound technology, have the ability to measure fluid velocity and calculate volumetric, mass, and totalized flow. The use of ultrasonic flow measurement is prevalent in the oil and gas, nuclear, wastewater, pharmaceutical, and food and beverage industries. It is also employed in energy management systems as a means to measure energy demand.

ultrasonic flowmeterFor intrusive flow meters, sensors are fitted opposite one another and alternate bouncing ultrasonic signals back and forth in the pipe, in an almost tennis-like format. In an elementary explanation, by increasing the number of sensors, engineers are able to decipher flow proportions through calculations of velocity between sensory transmissions; thereby, the flow volume can be computed.

For externally mounted flow meters, a clamp-on device affixes the flow meter measurement elements to the pipe. One special characteristic of clamp-on flow meters is the ability to transmit ultrasonic signals through piping up to four meters in diameter, making them suitable for application in very large systems such as those found in hydroelectric or wastewater installations. The clamp-on arrangement also facilitates addition of a flow measurement point to an existing system without process interruption.

The technology is pervasive in the processing industries, having its particular niche of applications where it excels. Proper installation is a key element in producing reliable and consistent results. Ultrasonic energy flow technology is used for custody transfer of natural gases and petroleum liquids. Custody transfer usually entails following industry, national, and government standards and regulations. Other popular applications include compressed air system monitoring and energy usage metering.

Ultrasonic flow meters, with no moving parts, are comparatively low maintenance and self-diagnosing. Temperature and pressure measurements are needed to calculate mass flow of gases. When measuring liquid mass flow in pipes, it is generally necessary for the pipe cross section to be media filled in order to obtain reliable results.

Whatever your flow measurement challenge, share it with a process measurement specialist. Combine your process knowledge with their product application expertise to develop effective solutions.

Tuesday, April 25, 2017

Campus & District BTU Energy Metering

Campus & District BTU Energy Metering
Saving energy through non-invasive
ultrasonic thermal energy management.
Measuring energy consumption for university campuses, medical centers and building systems is increasingly critical for conservation as well as for saving money. Energy and BTU metering of cooling and heating systems through the use of highly accurate, clamp-on flow metering instruments is taking hold in a wide variety of markets. Sectors include: large and small commercial complexes, industrial, government and university campuses, healthcare, and real estate. BTU measurement is an emerging market and is fast becoming critical for entities to remain cost-efficient and compliant. The document below (courtesy of Flexim) outlines the primary areas where this technology is used and how it is implemented. Anyone who manages or maintains a large commercial, medical, or governmental facility should contact a local expert to discuss the savings and efficiencies delivered with well-designed metering and communication system.

Tuesday, February 28, 2017

Non-invasive, Ultrasonic Flowmeters Are Clear Winners in Wastewater Pumping Stations

non-invasive flowmeters on wastewater pumping stations
Non-invasive flowmeters installed on
wastewater pumping line.
Pumping stations are an integral part of each wastewater network. Flow measurement at such stations is critical as the quantities which are fed to the treatment plant have to be monitored.

Conventionally, magnetic inductive flowmeters are used for such measurement tasks. However, due the medium, which is heavily charged with solid matter, these instruments are subject to wear, leading to incorrect readings and subsequent failure.

Non-invasive ultrasonic flow meters prove to be the better measuring solution. Since these meters measure from outside the pipe wall, there is no wear and tear on the meter making them virtually maintenance-free. Furthermore, there is no need to open the pipe for installation, which would result in at least a partial interruption of operation. There isn't a need for multiple workers or heavy equipment for installation. The entire measuring system, consisting of ultrasonic transducers and a measuring transmitter, is easily carried to the measuring location and installed by a single person. There is no disconnection of pipes or flanged joints, unlike when installing a magmeter. Finally, there is no need for block valves to hold back flow during installation, repair, or replacement.

  • Reliable and accurate non-invasive wastewater flow measurement without any wear and tear or measurement drift
  • Extremely easy to set up a measuring point without any impairment of the plant’s normal operation
  • ATEX-certified transducers with protection degree IP68 for use in hazardous areas as well as in flooded chambers
For more information on non-invasive ultrasonic flow measurement, contact Flow-Tech in Maryland at 410-666-3200, in Virginia at 804-752-3450, or online at

Thursday, October 13, 2016

Accurate Measurement of Low Flow In Compressed Air Systems

Plant operators are well aware of the cost associated with continuous delivery of compressed air, a useful medium utilized as an energy source. Large or multiple compressors consume considerable amounts of electric power maintaining system pressure and flow requirements. With extensive piping and countless fittings, there are many potential points of leakage. Scheduling of various production operations can vary the demand for compressed air significantly. Getting control of your compressed air system and reducing operating cost is a noble goal. One of the primary tools needed to manage energy costs will be accurate and reliable flow measurement equipment. Here are some characteristics of flow measurement instrumentation that should prove advantageous:
Portable ultrasonic flow meter with clamp on transducer
Portable Ultrasonic Flow Measurement Instrument

  • Non-invasive measurement from the outer pipe wall that does not add potential leak sources or pressure drop.
  • Availability in fixed or portable configuration.
  • Highly accurate, with paired temperature compensated traceable calibrated transducers
  • Installed without disturbance to piping.
  • Bidirectional measurement
  • Rugged instrument design suitable for any kind of industrial environment
Ultrasonic flow measurement technology can provide all of these characteristics, providing information that enables the operator to make fact based decisions about system design, management, and maintenance. Learn more about how ultrasonic flow meters specifically configured for compressed air system application can help you start reducing your operating cost and developing a higher level of control over your compressed air system. Share your process challenges with a product specialist and work together to build the best solution.

Monday, August 29, 2016

Flow Measurement of Activated Sludge

Flexim flowmeter
Better, non-invasive,
alternative for
activated sludge.
Reprinted with permission from Flexim

A wastewater treatment plant that serves 1,800 households includes several mechanical and biological wastewater treatment facilities.

The mechanical treatment consists of a screening system and an aerated circular grit trap. The biological treatment is carried out in a combi-tank (biological treatment stage outside, secondary clarifier-settler basin inside).

The plant also includes facilities for the removal of nitrogen which is carried out by intermittent nitrification/denitrification. In addition, the plant also has a static sludge thickener. The activated sludge, which has been formed in the biological treatment stage through the growth of microorganisms, slowly separates via gravity in the secondary clarifier basin.

A portion of the activated sludge is fed back into the biological treatment stage as return sludge and mixed with the newly added nutrient-rich wastewater. The amount of return sludge should always be in a defined ratio to the current feed quantity. For this reason, the flow rate of the recirculation pipeline has to be measured.

The installation of a wetted magnetic-inductive flowmeter, which is very common in the water and wastewater industry, would have required modifications to the piping and subsequent expensive civil engineering work. The only available manhole location on the buried recirculation pipeline has not been suitable for retrofitting a magnetic-inductive flowmeter. Moreover, the pipeline in the manhole is always submerged in water.

Retrofitting the measurement point with a FLEXIM non-invasive ultrasonic flow meter, including IP68 fully submersible transducers, proved to be a convincingly simple, accurate, reliable and cost effective solution.

There is no need to open the pipeline when mounting the transducers onto the outside of the pipe and therefore no interruption to operation. The cramped installation point in the flooded shaft does not pose a particular challenge to FLEXIM’s measuring system: the IP68 transducers can be operated while permanently submerged and, since they were installed, they have been providing highly reliable measurements for automatic control of the pumps that convey the return flow quantity of the activated sludge.

  • Reliable and accurate flow measurement of activated sludge for automatic pump control
  • Secure automatic control of the recirculation proportional to the demand
  • Easy to retrofit measuring point during ongoing operation, without any pipe work and without the need to modify the existing pipeline system
  • No expense for civil engineering and excavation work
  • Submersible IP68 transducers guarantee long-term stable measurements

Friday, July 22, 2016

The Transit-Time Difference Method to Measure Flow

Transit-time flowmeter
Transit-time flowmeter
(courtesy of FLEXIM)
The transit-time difference method for measuring flow exploits the fact that the transmission speed of an ultrasonic signal depends on the flow velocity of the carrier medium.

Similar to a swimmer swimming against the current, an ultrasonic signal moves slower against the flow direction of the medium than when in the flow direction.

For the measurement, two ultrasonic pulses are sent through the medium, on in the flow direction, and a second on against it. The transducers are alternatively working as an emitter and receiver.

The transit-time of the ultrasonic signal propagating in the flow direction is shorter than the transit-time of the signal propagating against the flow direction.

A transit-time difference, Δt, can thus be measured and allows the determination of the average flow velocity based on the propagation path of the ultrasonic signals.

An additional profile correction is performed by the proprietary FLEXIM algorithms, to obtain an exceptional accuracy on the average flow velocity on the cross-section of the pipe - which is proportional to the volume flow.

Since ultrasounds propagate in solids, the transducers can be mounted onto the pipe. The measurement is therefore non-intrusive, and thus no cutting or welding of pipes is required for the installation of the transducers.

Friday, May 6, 2016

Accurate Thermal Metering Using Non-Invasive Technology For Building HVAC Energy Management

BTU meter non-invasive ultrasonic technology
Specialized Ultrasonic Flow Meter for BTU Metering
Courtesy Flexim
The modern business climate has, for some now, been spooling up demand for accountability and, even more so, efficiency. Whether you think of efficiency as "doing more with less" or just avoiding the waste of financial, human, or natural resources the end result is the same and calls for similar prerequisites.

We live in a society of buildings, each with a mapped out function. Most buildings are predominantly occupied by people, bringing a requirement to maintain temperature, relative humidity, and air quality at levels of suitable comfort for human occupants. The energy consumption involved with providing that level of comfort stands as a bold line item in the operating expense ledger for any building. That is where accountability and efficiency come in. It is in the building stakeholders' interest to have knowledge regarding rates and quantity of thermal energy usage, as well as efficiency measures of delivered output per unit of input energy.

HVAC (Heating, Ventilation, Air Conditioning) primarily is an endeavor that generates and moves thermal energy throughout an enclosed space. Commercially available technology now allows a building operator to accurately measure that movement of thermal energy throughout a system or building. The process is generally called BTU metering and has a number of justifiable benefits.

  • Real time equipment performance measurement.
  • Sub metering can indicate specific areas of consumption.
  • Ability to directly bill multiple tenants in a single building for their thermal energy usage.
  • Monitor and balance energy flows.

BTU metering essentially involves inlet and outlet temperature measurement of heat transfer liquids, along with their flow rate. While the principle is simple, the intricacies of the measurement methods and equipment accuracy can have a substantial impact on the accuracy, and thus the benefit, of the measurement data. Additionally, adding more instrumentation to an already complex system can create an additional on-going maintenance and calibration burden to retain the necessary levels of accuracy and function. Success at gaining the benefit of the performance data while minimizing the additional maintenance burden due to the instrumentation should be the goal.

One solution calls for the use of clamp on ultrasonic flow meters to measure liquid flow, coupled with temperature measurement in a single unit that will perform necessary calculations and provide output data in useful engineering units. An overarching benefit of the clamp on meter is its non-invasive nature, allowing its retrofit to in-place systems with no disturbance to existing piping. Here are some other characteristics of a highly effective BTU measurement unit:
  • No wear mechanism as part of the flow measurement unit
  • Traceable accuracy of flow and temperature measurements
  • Simple installation in new or retrofit applications without disruption to system operation
  • Reliable and maintenance free operation
  • Accurate measurement from near zero flow rate to maximum system flow
  • Stable sensing with no zero drift
  • Communications protocol to match building energy management system
  • Large storage cache for data, in case of communication failure
  • Common output signals, 4-20 ma or other, usable with selected ancillary equipment
Selecting the right equipment or instrumentation is the most important step along the path of adding measurement capability to increase efficiency. Without a solid stream of reliable data, useful decisions become difficult. Contact a product application specialist and share your requirements and goals. Combining your process and system knowledge with their product application expertise will produce a good outcome.

Sunday, March 27, 2016

Campus Metering: Improve the Energy Efficiency of Your Building with Clamp-on Flowmeters

Clamp-on, Ultrasonic Flowmeter
Clamp-on, Ultrasonic Flowmeter
(courtesy of FLEXIM)
Today there are many reasons to focus on energy optimization efforts. Due to rising cost of fossil fuels and environmental concerns, decreasing overall energy consumption, decreasing operational costs, improving HVAC performance, improving building quality and certification rating is becoming increasingly important. Facility Managers are stepping up their efforts to find efficiency and savings related to heating, ventilation and air conditioning systems, including chillers, boilers, and air-handling components. Energy-efficiency is a top priority for institutional and commercial organizations and will continue to grow in importance for the foreseeable future.

Finding new ways to reduce energy consumption in buildings without compromising comfort and indoor air quality is an ongoing challenge. One of the most significant options a facility has is to add BTU energy metering that is able to accurately meter the new performance of upgraded chillers, pumps, and chilled water distribution system.

Superior precision can be achieved by using clamp-on flowmeters with specially matched and paired ultrasonic transducers and temperature probes that control the heating and cooling flows within the building. These devices offer a superior solution with a high degree of reliability and repeatability for both temporary and permanent applications.

The biggest challenge in retro-fitting flowmeters in existing piping structures are the very tight piping typical of chiller plants, existing valves, vents, and pipe bends. Clamp-on ultrasonic flowmeters provide an easy work-around. Since the clamp-on ultrasonic transducers are simply mounted on the outside of the pipeline, plant operation is not affected in any way during retrofitting. The reworking of existing piping systems for flowmeter installation is not required, making the clamp-on flow meters an ideal solution for retrofitting existing facilities.

Designed with temperature compensation to eliminate inaccuracies or drift through deviations, and powerful correction algorithms to compensate for non-ideal pipe conditions, these energy flow meters offer an accuracy of 1% or better on the flow rate. Plus, low flow velocities can be detected reliably and accurately.

The advantages for choosing clamp-on ultrasonic flowmeters for HVAC retrofit are:

  • Reliable, non-invasive recording of thermal energy (BTU) flows
  • Practically wear-free measurement without measurement drift, unaffected by potential coating formations
  • Works independently of the conductivity of the medium
  • Simple set-up of measuring points without any interruption of operation
  • Minimum installation effort
  • Compact measurement system, can also be easily installed on measuring points which are difficult to access

Research demonstrates the addition and/or upgrade of metering existing HVAC systems can offer effective solutions for energy conservation and thermal comfort, with possible energy savings in the range of 30-40%.

For more information on BTU/Campus/Building Metering, contact:

Flow-Tech, Inc.
10940 Beaver Dam Rd
Hunt Valley, MD 21030
Ph: 410-666-3200

Central VA Office
10993 Richardson Rd#13
Ashland, VA 23005
Ph: 804-752-3450

Friday, March 11, 2016

Efficiently Detect Condensate in HRSG Drain Lines

Flexim WaveInjector sensor modified for HRSG Drains
The development of condensate in super heater and re-heater drains leads to trouble in combined cycle and cogeneration plants with heat recovery steam generators (HRSGs). The need to reliably detect and measure condensate in these drain lines is just beginning to emerge.

The Problem 

Heat recovery steam generators were never designed for cyclic service. The move toward renewable energy resources (such as wind and photovoltaic), in tandem with the ability of the combined cycle plant to start-up and stop quickly, is expanding the role of the combined cycle plant as a backup source of power. With frequent starts/stops condensate management becomes a problem. Draining this condensate is critcally important for the safe and reliable operation of the boiler. While the problem of condensate drainage has been around for years, the problem is far greater now with the more frequent start/stop cycle rates. The importance of finding a good solution for detecting condensate in the HRSG drain lines is growing.

Boiler manufacturers address this situation through the use of condensate pots, levels instruments, site glasses, and valves. None of these technologies provide a satisfactory combination of reliability, economy, and efficiency. Knowing when steam converts to water is difficult with this approach. Plus, over cautious systems sometimes release steam instead of condensate, wasting energy. A more reliable and consistent way to sense the presence of water in drain lines had to be found.

The Solution

By designing specialized mounting and tooling, modifying their sensing diagnostics, putting in hundreds of hours of field testing, and investing hundreds of hours improving their firmware for water detection, the manufacturer Flexim developed an ultrasonic flow meter that elegantly and reliably solves the HRSG drain line problem.

These clamp-on sensors work by measuring the transit-time difference of an ultrasonic signal, at varying flow velocities, through the process media. Ultrasonic, clamp-on flow meters have no moving parts, are not affected by density, and are mounted non-invasively directly to the pipe.

The most challenging aspects of this application are the high temperature sensor exposure and the thick-walled pipes with small diameters commonly used for drains.  To handle the high temperatures, specialized mounting and tooling were developed for the sensor allowing for pipe temperatures up to 750 deg. F. To overcome the small diameter / think pipe issue, Flexim engineers reconfigured the sensor’s firmware to change from measuring flow rate, and instead measure noise (decibels) as a innovative way to distinguish steam from water.

Flexim’s unique ability to measure the presence of liquid in condensate drain pipes is a revolutionary development. This valuable solution helps customers run longer and safer, minimizing downtime.

For more information, contact:

10940 Beaver Dam Rd
Hunt Valley, MD 21030
Ph: 410-666-3200

Central VA Office

10993 Richardson Rd#13
Ashland, VA 23005
Ph: 804-752-3450