March 2009 Vol. XV, No.3 • www.FlowControlNetwork.comMarch 2009 Vol. XV, No.3 • www.FlowControlNetwork.com

Wireless Standards Outlook • Flowmeter Diagnostics • Sight-Flow Best PracticesWireless Standards Outlook • Flowmeter Diagnostics • Sight-Flow Best Practices

Thermal Flowmeters Buck Woeful Economyon Environmental Monitoring PushThermal Flowmeters Buck Woeful Economyon Environmental Monitoring Push

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Among the established flow measure-ment technologies, thermal flowme-ters account for fewer units shipped

than any other flow technology except fortarget meters. In perspective, thermalflowmeters, at a market size of under $100million, represent less than 2 percent of aworldwide flowmeter market that is pro-jected to approach $5 billion in 2009. Yet,despite a global economic slump, thermalflowmeters are suddenly emerging into thespotlight and are primed to show anupswing in demand. Why is this? Theanswer lies primarily in the trend towardincreased environmental monitoring andthe suitability thermal flowmeters have forsuch applications.

How Thermal Flowmeters WorkThermal flowmeters are used almostentirely for gas flow applications. As thename implies, thermal flowmeters useheat to measure flow. Thermal flowmetersintroduce heat into the flowstream andmeasure how much heat dissipates usingone or more temperature sensors. Thismethod works best with gas flow meas-urement. It is difficult go get a strong sig-nal using thermal flowmeters in liquids,due to considerations relating to heatabsorption.

While all thermal flowmeters use heat tomake their flow measurements, there aretwo different methods for measuring howmuch heat is dissipated. One method iscalled the constant temperature differential.Thermal flowmeters using this methodhave two temperature sensors — a heatedsensor and another sensor that measuresthe temperature of the gas. Mass flowrateis computed based on the amount of elec-trical power required to maintain a con-stant difference in temperature between thetwo temperature sensors.

A second concept is called a constant-current method. Thermal flowmeters usingthis method also have a heated sensor andanother one that senses the temperature ofthe flowstream. The power to the heatedsensor is kept constant. Mass flow is

measured as a function of the dif-ference between the temperatureof the heated sensor and the tem-perature of the flowstream. Bothmethods are based on the princi-ple that higher velocity flows resultin a greater cooling effect. Bothmeasure mass flow based on themeasured effects of cooling in theflowstream.

Limitations of ThermalFlowmetersWhile thermal flowmeters areuniquely capable of supportingmany gas flow applications, theyhave a limited application for liq-uids, and they are not a good fitfor steam flow measurement. Thisexplains why thermal technologiesaccount for such a small share ofthe overall flowmeter market, asgas flow accounts for only about20 percent of total flow applica-tions. And many of these applica-tions are in process gas and other

A Market Prime for BoomThermal Flowmeters Positioned to Gain from Environmental Push

by Jesse Yoder, Ph.D.

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2007 2008 2009 2010 2011 2012

Total Shipments of Thermal Flowmeters

Worldwide (Millions of Dollars)

Thermal flowmeters based on the constant-currentmethod use two temperatures sensors, one of which isexposed to a constant power source. Mass flow ismeasured as a function of the difference between thetemperature of the heated sensor and the temperatureof the flowstream. Image courtesy of Fluid ComponentsInt’l (www.fluidcomponents.com).

Source: Flow Research Inc.

non-custody transfer applications. Thermal flowmeters do not have the

necessary industry approvals for use withcustody-transfer of natural gas in pipelines.This market is dominated by ultrasonic,turbine and differential-pressure flowme-ters, all of which possess custody-transferapprovals from the American GasAssociation (AGA, www.aga.org). Thermalflowmeters are unlikely to achieve thisapproval without technological break-throughs that would increase measurementaccuracy to the very high level required forcustody transfer.

CEM Boosts Thermal FlowmetersOn the other hand, thermal flowmetershave carved out a unique niche in theflowmeter market due to their ability to helpend-users maintain compliance with certainenvironmental requirements. In the early1990s, for example, new environmentalregulations mandated that companiesdetect and reduce the emission of sulfurdioxide (SO2) and nitrous oxide (NOX) —both of which were found to be principalcauses of acid rain.

By combining a measurement offlowrate with a measurement of the con-centration of SO2 and NOX, it is possible todetermine how much of these substancesare released into the atmosphere. As such,by regulating SO2 and NOX emissions, theU.S. Environmental Protection Agency hasdeveloped an entire industry aroundContinuous Emissions Monitoring (CEM).

In response to the trend toward CEM,thermal flowmeter companies developedmultipoint thermal flowmeters. In manycases, continuous emissions monitoringoccurs in large stacks that emit pollutionfrom industrial sources. Single-point ther-mal flowmeters measure flow at a point,making it difficult to accurately computeflow in a large pipe or smokestack.Multipoint thermal flowmeters measure gasflow at multiple points, and use these val-ues to compute flow for the entire pipe,duct or stack. Some multipoint flowmetershave as many as 16 measuring points,which enables them to support some of thelarge smokestack applications require forCEM. Thermal flowmeters, due to theirinsertion style, are one of the few types offlowmeters that can accurately measuregas flow in such large pipes.

A New Age of Environmental AwarenessWhile the need for CEM is ongoing, the21st century has brought new environmen-tal awareness and requirements. Scientificthinking has evolved substantially in thepast 10 years, and while global warmingand the need to reduce carbon emissionswere once viewed as scientific theory, theyare now widely accepted as scientific fact.

In the United States, for example, theObama administration has made a commit-ment to reducing greenhouse gas emission80 percent by 2050. The new administra-tion is also pledging to make the UnitedStates a leader in climate change, whichfigures to make emissions monitoring afast-growing application segment for theforeseeable future.

Clearly, it is not just in the United Stateswhere the effort to reduce greenhouse gasemissions is resulting in market opportuni-ties for thermal flowmeter providers. TheKyoto Accord, for example, has resulted inthe creation of several mechanisms thatrequire measurement of greenhouse gasesinternationally. These include CertifiedEmission Reductions (CER), which is acredit system designed to aid European

Union countries in achieving emission limi-tation targets covered by the EuropeanUnion Emission Trading Scheme. Anotherprogram is the Clean DevelopmentMechanism (CDM), which allows countriesto invest in sustainable development proj-ects that reduce emissions in developingcountries.

This new age of environmental aware-ness, together with the Kyoto Accord andother greenhouse gas initiatives, has result-ed in a rewriting of the rules on measuringindustrial emissions. There is suddenly aneed and demand to measure greenhousegases in applications that formerly mayhave gone unnoticed. Many of these appli-cations present opportunities for thermalflowmeters, including the following:• Measurement and recovery of landfill

gas – Landfills produce carbon dioxide,methane and a mixture of other gases.These gases are measured as they leavethe landfills, extracted from different well-heads, and collected to a common head-er pipe. The collected gases are disposedof or recovered as a fuel source.

• Ethanol distillation and refining –Ethanol production is a complex processinvolving both fermentation tanks anddistillation tanks. Thermal flowmetersmeasure the flow of air and fuel goinginto the distillation tanks, and the CO2leaving the fermentation tanks.

• Measuring emissions from steam gen-erators, boilers, and process heaters –Thermal flowmeters measure these emis-sions, especially NOX and carbon monox-ide.

• Biomass gasification – Organic industrialwaste and food waste can be digested inaerobic conditions in reactor tanks andfermentation towers. The output from thisprocess is called biogas. Biogas includesmethane, carbon dioxide, and a mixtureof other gases. Thermal flowmeters areused to measure gas flow at multiplepoints along the way, providing optimalproduction, control and reporting.

• Recovery of methane from coal mines– Methane that is recovered from coalmines often is mixed with air, carbondioxide, and nitrogen. It is important foraccurate flow measurement to calibratethe flowmeter with the actual mixture ofgases. Thermal flowmeters are used tomeasure the amount of extracted gases

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Here an immersible thermal mass flowmeter is usedin a bio gas application. Photo courtesy of SierraInstruments Inc. (www.sierrainstruments.com).

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Thermal Flowmeters – Then to Now

The history of the thermal flowmeter market in southernCalifornia reads a little like the beginning of the book ofMatthew in the New Testament. According to the first part

of Matthew, Abraham begat Isaac, Isaac begat Jacob, andmany generations followed. In the case of the thermal flowme-ter companies, there were three “father” companies founded inthe 1960s and 1970s — Sierra Instruments (www.sierrainstruments.com), Fluid Components International (www.fluidcomponents.com) and Kurz Instruments (www.kurz-instruments.com). In 1988, 1994 and 2002, former employeesof these companies formed three more companies. Thesecompanies are Eldridge Products (www.epiflow.com), FoxThermal Instruments (www.foxthermalinstruments.com), andSage Metering (www.sagemetering.com).

How it All StartedFluid Components International (FCI), founded in 1964, was thefirst company in the group to be formed. Mac McQueen andBob Deane jointly founded FCI. John Olin, Ph.D. and Jerry Kurz,Ph.D. together formed Sierra Instruments in 1973. In 1977, Dr.Kurz formed Kurz Instruments, leaving Dr. Olin with sole own-ership of Sierra Instruments.

Even though FCI, Sierra, and Kurz all ended up making ther-mal flowmeters, they each approached this subject from differ-ent perspectives. FCI began by manufacturing thermal flowswitches to detect the movement of flow in oil-well pipes inBakersfield, Calif. While FCI was the earliest of the thermalcompanies to be founded, it didn’t get into the flowmeter busi-ness until 1981. That year, FCI began putting more sophisticat-ed electronics on its flow switches, enabling the company tocreate its first thermal flowmeters for gas flow measurement.

By contrast, Sierra Instruments got into the market by creat-ing air-sampling products and thermal mass flowmeters. Thethermal mass flowmeters took the form of portable air-velocitymeters and transducers. When Dr. Kurz formed KurzInstruments in 1977, the thermal flowmeters went to Kurz,while Sierra Instruments retained the air sampling products.These instruments measured particle size and distribution inthe air. It was not until 1983 that Sierra got back into theflowmeter market.

The origins of both Sierra’s and Kurz’s thermal flowmetersgo back to their founders’ research using hot-wire anemome-ters. Dr. Kurz and Dr. Olin worked together for Thermo-Systems Inc. (TSI) in Minnesota from 1968 through the early1970s. They used hot-wire anemometers in their research. Hot-wire anemometers, which consist of a heated, thin-film ele-ment, are used in velocity profile and turbulence research.While these fragile instruments are suited for research environ-ments, they are too light for industrial environments, since theybreak easily. Both Kurz and Olin would later sell industrial ther-mal flowmeters that worked somewhat like the hot-wireanemometers, but were ruggedized and hardened to fit intomore demanding industrial environments.

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The FoundingCompaniesTodayFCI is the onlyCalifornia thermalflowmeter compa-ny not located inthe Monterey area.Instead, FCI islocated in SanMarcos, Calif., justnorth of San Diego.

Of the threecompanies, SierraInstruments is theonly companyamong the group to offer mass flow controllers (MFCs), in addi-tion to industrial thermal mass flowmeters. Sierra sells its MFCsinto both semiconductor and industrial markets. Sierra also hasexpanded into the vortex and ultrasonic flowmeter markets. FCIand Kurz mainly remain focused on the industrial thermal flowme-ter market.

Each of the thermal flowmeter companies has distinguisheditself by focusing on particular industries and applications. FCIemphasizes wastewater treatment applications and flare gasmeasurement and monitoring. The company also offers solutionsfor landfill gas recovery, biogas recovery, and ethanol productionand refining.

Sierra Instruments has developed thermal flowmeter solutionsfor air and natural gas flow measurement, including applicationswith mixtures of different gases. Sierra’s thermal flowmeters areused in a range of industries, including pharmaceutical, biotech,petrochemical, and metals processing. Applications include com-bustion airflow,natural gas fuelflow, custodytransfer, andstack gas emis-sions monitoring.

KurzInstruments isespecially activein the powerindustry. Kurz hasdeveloped aseries of single-point and multi-point insertionthermal flowmeters for stack-gas and flare-gas monitoring. Kurz’sflowmeters are also used in the refining, cement, pulp & paperand other process industries.

New Companies EmergeThe first of the offspring companies was established in 1988 byMark Eldridge as Eldridge Products. Previously, Eldridge had

Mark McMahon, scientific product manager, MattOlin, president and CEO, and Scott Rouse, indus-trial product manager, for Sierra Instruments.Sierra was co-founded in 1973 by Olin’s father,John Olin, Ph.D., with Jerry Kurz, Ph.D.

Jerry Kurz, Ph.D., (center) pictured here with hissons Daniel Kurz (left) and Jerry Kurz, Jr. (right)celebrating Kurz Instruments’ 30th anniversaryin 2007.

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worked forKurzInstruments.Still located inMonterey,Calif., Eldridgespecializes inthermalflowmeters forgas submeter-ing, com-pressed-airmonitoring,and water &wastewater

treatment.Eldridge exclusively offers thermal mass flowmeters.

Fox Thermal Instruments was founded in 1994 by BradLesko, a former employee of Kurz Instruments. Fox is locat-ed in Marina, Calif., which is near Monterey. Fox specializesin thermal flowmeters for compressed-air monitoring, emis-sions monitoring, and fuel monitoring applications.

Sage Metering is the newest member of the thermalflowmeterclub. BobSteinberg,formerlyanemployeeof Sierra,Kurz, andEldridge,foundedSage in2002.Sage islocated inMontereyand hasdevelopeda number of unique features in its thermal flowmeter line,including a user-friendly transmitter display, a touch screen,and digital electronics. Sage’s thermal flowmeters are used ina variety of applications, including biogas, digester gas, andlandfill gas monitoring.

While the focus here has been on thermal flowmeter com-panies in California, other companies have also entered thethermal flowmeter market. These includes Endress+Hauser(www.us.endress.com), ABB (www.abb.com), Intek(www.intekflow.com), Thermal Instrument Co. (www.ther-malin strument.com), Tokyo Keiso (www.tokyokeiso.co.jp),Magnetrol International (www.magnetrol.com), andBronkhorst (www.bronkhorst.com). Expect to see morecompanies entering this dynamic and exciting market.

Mark Eldridge, president (pictured left), andCraig Schieding (pictured right), director ofsales and marketing, of Eldridge ProductsInc. Eldridge formerly worked for KurzInstruments prior to founding his own ther-mal flowmeter company in 1988.

Bob Steinberg, president of Sage Metering Inc.,worked for Sierra Instruments, KurzInstruments, and Eldridge Products before star-ing his own thermal flow company in 2002.

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recovered from coal mines. • Monitoring of flue gas – Flues typically are large pipes, stacks,

ducts or chimneys that dispose of gases created by a combustionprocess. Thermal flowmeters measure the flow of gases throughflues. This is often required by environmental regulations.

• Measurement and monitoring of flare gas flow – Flare systemsare used to burn off waste gases from refineries, process plantsand power plants. Flares can be a single pipe or a complex net-work of pipes. Flares are subject to strict environmental regula-tions. Thermal flowmeters are used to measure the amount of gasflared.

The applications noted here provide a mere sampling of the growingnumber of scenarios that require measurement of greenhousegases. Thermal flowmeters are uniquely suited to make these meas-urements because their insertion technology allows them to handlelarge pipe sizes and because they can accurately measure differentmixtures of gases. The need for these measurements figures togrow substantially in the next 5-10 years. As a result, so will thedemand for thermal flowmeters.

Jesse Yoder, Ph.D., is president of Flow Research, Inc. in Wakefield,Mass., a company he founded in 1998. He has 22 years of experi-ence as an analyst and writer in process control. Yoder specializes inflowmeters and other field devices, including pressure and tempera-ture products. He has written over 100 market research studies inindustrial automation and process control and has published morethan 90 journal articles on instrumentation topics. Dr. Yoder can bereached at jesse@flowresearch.com or 781 245-3200.

www.flowresearch.com

Flow Research is currently working on a new market study coveringthermal flowmeter technology. The study, titled “The World Marketfor Thermal Flowmeters”, is scheduled to be published in May 2009.For more on this study, visit www.flowthermal.com.

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Stack emissions flow applications are growing in importance due to envi-ronmental regulations, and thermal flowmeters are particularly well suitedto provide such measurements. Image courtesy of Fluid Components Int’l(www.fluidcomponents.com).