Tag Archives: Thermal Mass Flow Meters

Five Ways QuadraTherm Flow Meter Technology Makes You And Your Process Smarter

For engineers and facility managers looking at their production operations to improve process efficiency, reduce costs, and find ways to meet sustainability and environmental governance regulations, selecting the right thermal mass flow meter with accurate flow measurement is critical. 

Utilizing a flow meter that lacks the capabilities to accurately measure your gas flow in your application results in a multitude of issues and ultimately cost more money down the road. These pitfalls include:

  • Poor accuracy and ongoing sensor drift results in inferior data
  • Utilizing more than one device to measure temperature, pressure, and flow results in increased installation costs, potential down time, and maintenance costs
  • Flow conditions and gas compositions can change over time. These changes will impact the meters ability to report accurate information. Is your meter equipped to handle these modifications without having to be sent back to the factory?

5 Ways QuadraTherm 640i with qMix Makes You and Your Process Smarter

How can instrumentation make you smarter? We get that accurately measuring flow is tough. You can’t see flow, but you know it’s there.

Most flow meters on the market are so restrictive in terms of their application parameters. It’s got to be the right pipe size, calibrated for specific gases for a specified  full-scale range.

QuadraTherm   technology allows you to change anything you want in the field-making your job easier and your process smarter.

Sounds too good to be true? Let us break it down for you.

#1 World’s Most Accurate Thermal Flow Meter

Achieve extreme precision with “percent of reading” accuracy rivaling accuracies of Coriolis technology over a wide flow range up to 60,000 sfpm (305 smps).

  • +/- 0.5% of reading (inline)
  • +/- 0.75 of reading (insertion)
  • Industry’s only ultra-low flow calibration from 0 to 499 sfpm or any value between for any pure gas or gas mixture
  • 40-point calibration available for highest accuracy

Bottom line: Your gas flow measurement will have precision accuracy, so you know what’s running through your pipe, even if that gas composition changes.


#2 Patented 4-Sensor Technology

Different molecules of gas transfer heat at a different rate, so sensor technology and stability is critical for accuracy.

  • Four-sensor technology provides the critical inputs for the Raptor OS’ living, learning algorithm used in the qTherm brain
  • Three platinum temperature sensors and one patented DrySenseTM mass velocity sensor
  • Eliminate drift with DrySenseTM sensor technology
  • Lifetime limited sensor warranty

QuadraTherm’s patented 4-sensor technology is the physical aspect of how we make the direct mass flow measurement to provide precision accuracy.

#3 qTherm “Brain” Optimizes Field Intelligence

qTherm “brain” manages changes in gas, internal and external temperature, and pressure via a comprehensive heat transfer model using only true variables which instantly calculate precise, stable and accurate mass flow measurement.

  • Solves the first law of thermodynamics
  • Enables Dial-A-Pipe
  • Insertion – adapt to any pipe size 2 inches or greater and pipe roughness
  • Inline – built-in flow conditioning eliminates straight run requirements

#4 qMix Manages gas Composition Changes

  • Use qMix software to easily create pure gases or any gas mixture in the field and retain accuracy – no additional factory calibration necessary
  • Meet EPA emissions regulations like “Quad O”
  • Dial-A-Gas
    • 3 gas slots for any gas or gas mixture you want; air comes standard
    • Accommodates multiple full scales for same gas or gas mixture
    • Capable of increasing full scale by 2x
  • Use “My Gases” Library to store unlimited new qMix gas compositions
  • qMix RealTime Flare Management System (FMS) Delivers Real-Time Flare Gas Measurement:
    • qMix RealTime app connects, reads and updates new flare gas composition from a GC-real time, no recalibration needed
    • Meet EPA rule 40 CFR 63-measure flare gas down to 0.1 sfps (0.03 smps) where ultrasonic flow meters can’t operate
    • Easy to install with current ultrasonic flow meters, no process shutdown

#5 World-Class Flow Calibration Ensures Accuracy

How your meter is calibrated matters.

  • Advanced gas loop delivers highest accuracy
  • Specifically designed for industrial thermal calibration – Over $2 million invested
  • Closed gas loop with pressurization, temperature control and NIST traceable calibration standards
  • Calibrated full scales up to 30,000 sfpm, any gas or gas mixture
  • Calibrated full scales up to 60,000 sfpm with slight de-rate of accuracy for any gas or gas mixture

Additional beneficial features

  • No moving parts
  • Hot-tap for easy install-no process shutdown
  • InSitu calibration with the ValidCal app validates original calibration in the field
  • Digital communications available
    • HART, Modbus, Fieldbus
  • Approvals available cFMus – Explosion proof for Class 1, Div 1, Groups B,C,D
    • CE – European Conformity
    • ATEX/IECEx
    • Canadian Registration (CRN number)
    • GOST R
    • Chinese Pattern

Discover more about QuadraTherm technology and how it can help you in your process by downloading the QuadraTherm Tech Guide.

Want to learn even more? Watch these great videos featuring QuadraTherm technology:

Take Control of Your Facility’s Flow Measurement

How to Achieve Maximum Boiler Efficiency

Breakthrough in Flare Gas Measurement

qMix RealTime Flare Measurement System – How it Works


Understanding Flow Measurement for Emissions Monitoring

Take Charge of Your Boiler Efficiency & Avoid Steep EPA Emissions Fines
Sounds like an impossible task, but it’s not.

Emissions monitoring is a hot topic for plant and facility managers due to the elevating importance of three factors:

  1. Global climate-change mitigation efforts
  2. Increasing governmental regulations
  3. Social pressures

Due to this, there is also a heightened importance to accurately measure gas flow for high boiler and process-heater efficiency.  Why? Because accurate flow measurement is critical to achieving boiler efficiency.

Measuring Flow in Your Boiler

In emissions control and combustion applications, flowmeters are used to measure the flow of fuel gas (normally natural gas) and air to combustion burners within various types of process equipment to maintain a fuel-to-air ratio that will maximize efficiency while producing minimal pollutant products. Ratios that are either too rich in natural gas, or too lean, will result in unnecessary emissions and wasted fuel.


Flow measurement technologies can be used in industrial boilers to monitor the air and fuel inlet, as well as the water inlet and the steam outlet

If the flow of gaseous combustion products — including greenhouse gases like carbon dioxide, carbon monoxide, nitrogen oxides (NOx) and unburned methane — as well as the fuel input, can be measured accurately, users can gain a full picture of the boiler’s efficiency. Accurate measurement of steam production determines whether a boiler is producing the expected amount of steam for the fuel input, or if the boiler needs to be tuned for increased efficiency.

What is Boiler MACT?

Large facilities like petroleum refineries and chemical manufacturing facilities with boilers and process heaters  must meet emissions requirements established in the National Emission Standards for Hazardous Air Pollutants (NESHAP) for industrial, commercial, and institutional boilers and process heaters standards, issued by the EPA which are based on Boiler MACT.

Boiler MACT (Maximum Achievable Control Technology) is an EPA rule to limit hazardous air pollutants (HAP) from commercial and industrial boilers and process heaters.  Driven by the Clean Air Act, the rules are Area Source Boiler MACT 40 CFR 63, subpart JJJJJJ for smaller boilers (stores, hotels, apartments, small manufacturers, etc.) and Major Source Boiler MACT subpart DDDD for large boilers (petroleum refineries, chemical and large manufacturing plants, large facilities).

The rules require two things from manufacturers:

  1. Facilities must monitor the amount of emissions of carbon monoxide, particulate matter, mercury, HCl, and other pollutants.
  2. Requires end-users to “tune” new boilers when they first start up, and then perform periodic tuning to measure the boiler’s efficiency in combusting the fuel and turning the water into steam.

Tuning Your Boiler

Tuning a boiler or process heater involves inspecting the flame pattern and adjusting the burners, as well as inspecting the system that controls the air-to-fuel ratio to ensure it is correctly calibrated and operating properly. Facilities that tune their boilers to ensure the maximum boiler efficiency can simultaneously minimize the amount of air pollutants generated.

A well-tuned boiler is 80% efficient.  If your boiler is less than 80% efficient then you are wasting energy and releasing hazardous air pollutants into the environment unnecessarily.   Improving the suboptimal efficiency could involve repairing leaks, adding insulation and cleaning heat exchanger tubes.

Highly efficient boilers and process heaters minimize the release of greenhouse gases, and accurate flow measurement is an essential part of achieving high efficiency. Flowmeter manufacturers with Boiler-MACT-compliant devices are capable of measuring the combustion gases produced.

Flow Measurement Technologies to Improve Boiler Efficiency

Flowmeters can help meet Boiler-MACT emissions limits and there is a wide range of technologies available for the measurement of gas flowrate in closed pipes for applications involving combustion and steam. Flowmeters can be categorized in several ways, but one approach is to divide them into four classes: mass, velocity, differential pressure, and positive displacement.

Available technologies include:

Key parameters for assessing the effectiveness of a flowmeter device include accuracy, durability, maintenance, and total cost of ownership. The different strength-and-weakness profiles for flowmeters partly depend on the requirements of the application, including whether the fluid being measured is a gas or liquid.

For this blog’s purposes, we are going to look at some of the available flow technologies.

Strengths and Weaknesses of Available Flow Measurement Technologies to Improve Boiler Efficiencies

The Best Choice for Optimizing Your Boiler Efficiency

For gas-flow applications, thermal mass flowmeters often emerge as the best choice. The newest models of thermal mass flowmeters are often able to overcome the limitations of previous models. For example, the accuracy of Sierra’s QuadraTherm thermal mass meters rivals that of Coriolis meters, but at lower prices. In addition, thermal mass flowmeters have wider application flexibility, and the efficiency and capabilities of the latest thermal mass flow meters have been enhanced to include better turndown ratios, minimal pressure drop and the ability to install the instruments without having to shut down a process.

Learn more about flow measurement for emissions monitoring and improving your boiler efficiency, download our new white paper “Understanding Flow Measurement for Emissions Monitoring.”

For more information about tuning your boiler, watch our “3 Tips to Improve Energy Efficiency” video or read or our previous blog, “Tuning Your Boiler for EPA Boiler MACT Compliance.”


DrySense Sensor Technology Is the Key to Thermal Flow Meter Accuracy

Why Are Dry Sensors Critical for Flowmeter Lifetime Sensor Warranty, Accuracy, and In-Situ Validation?

When it comes to flow meters, what matters to plant managers and engineers alike is if their meter is measuring flow accurately and reliably. They want to know they can depend on the data their meter is providing. However, the answer to this question really depends on the type of sensor design of the thermal mass flow meter. For this reason, designing a stable sensor that will last over the lifetime of your thermal mass flow meter is the holy grail in thermal mass flow meter design. However, the truth is most flow meter manufacturers use a “wet’ sensor design.

Wet Sensor Design

Why is a wet sensor problematic? As conditions in your application change, the sensor is heated and cooled over time, expanding and contracting the cement inside the sensor—and you know what happens to cement as it is repeatedly heated and then cooled, it shifts and cracks. This “wet” sensor design greatly compromises the accuracy of the thermal sensor over time.

Since thermal sensors are precisely calibrated to determine the heat transfer versus ­ flow characteristics, any change in the physical makeup of the sensor layers will invalidate this calibration, resulting in drift or outright failure. Excessive drift means users must send the meter back to the factory for recalibration.

DrySense Sensor Differentiator, No-Drift Stability

To minimize the drift in a thermal sensor the epoxies, cements and thermal greases that make up the wet sensor need to be removed.  Addressing this very need, Sierra introduced a patented dry sensor in 1999.

Patented Dry Sensor Technology

The patented no-drift DrySense velocity sensor technology uses a  proprietary swaging process which eliminates all air gaps between the heated velocity sensor and the tubular probe sheath eliminating the need for any potting compounds. The result is maximum sensitivity, reproducibility, immunity to cracking and shifting over time, and ultimately greatly improved accuracy, all backed by a lifetime warranty.

All materials used to make the sensor are selected to assure that the coefficients of thermal expansion are approximately the same. As a result, they expand and contract at the same rate, limiting the stress and cracking. Sierra determined that using a dry sensor was the only way a manufacturer could claim stability over the sensor’s lifetime.

Dry, no-drift sensors make accurate in-situ calibration validation possible. The all-metal, epoxy-free mechanical design provides the confidence that the in-situ calibration validation is actually valid. If the sensor innately drifts, in-situ calibration will inherently be inaccurate.

How DrySense Technology Works

Discover more about DrySense technology, by downloading the In-Situ Calibration white paper.

Editor’s Note: This post was originally published on March 1, 2015. Due to its popularity and continued questions on this issue, we updated the post on February 18, 2021. 

Now Measure All Flow Energy In Your Facility — One Solution — Three Metering Technologies

oil and gas refineryFacilities managers at large facilities often have the challenging task of managing all the flow energy in their facility with the mandate from upper management to save money on energy costs. To accomplish this goal, it’s critical to get accurate flow measurement data of the flow energy in your facility such as: natural gas, compressed air, steam, chilled and hot water.

The next challenge is to find the right flow meters for these gas, liquid, and steam applications. Often many different technologies are needed depending on the type of fluid being measured and many different flow meter companies must be used. Dealing with different companies and technologies can be very time consuming, expensive, and ultimately frustrating.

Sierra is tackling this issue with our new Big-3™ flow energy management strategy. Sierra now offers facilities managers a “one-stop shop” for all flow meters needed for effective flow energy management—all made in the USA and supported globally by our network of over 150 locations in over 50 countries.

We design and manufacture thermal mass flow meters for accurate compressed air and natural gas measurement, vortex shedding flow meters for steam and water measurement, and transit-time ultrasonic flow meters for liquid flow measurement. Product commissioning and training, lifetime tech support, and a global network of flow experts from one company make it easy to install and operate all gas, liquid and steam flow meters.

In addition, for easy integration into your facility, Sierra’s “Big-3” thermal, vortex, and ultrasonic (TVU) flow meters have:

  • Sierra’s commitment to great sensors with lifetime warranty—over 40 years of flow meter innovation and expertise
  • Shared firmware platform—Raptor OS operating system
  • Shared software apps for ease of use, so no learning new software and local display interface menu structures for each device
  • Major focus on excellent, fully automated, calibration facilities
  • Broad application capability (gas, liquid, steam)
  • One company, one point of contact for all three flow metering technologies
  • All designed, built and calibrated by Sierra in Monterey, CA USA

Watch Video

Let me explain more about Sierra’s new Big-3™ strategy and how it can help you transform your flow energy measurement strategy by watching this short video.

Download the Big-3 overview brochure.

Part 2-Flow Energy Management Applications-Installation Tips & Tricks

In part 1 of our Flow Energy Management series, we identified the 3 Killer Flow Energy Management Applications that will reduce energy costs: compressed air & natural gas measurement, steam production, distribution, and allocation, and water/BTU measurement. And we identified the best flow meters for each of these applications: thermal mass flow meters for gas, vortex flow meters for saturated and super saturated steam, and clamp-on ultrasonic flow meters for liquid/water flows. If you haven’t read part 1 of this article, we recommend these 3 Killer Apps to Lower Energy Costs With Efficient Flow Energy Management.

Now that we have identified the best flow meter for each type of fluid and application, proper installation is key for successful flow readings. Many times if you think your flow meter “doesn’t work”, it could just be that the meter was not installed properly.  In part 2 of our flow energy management series, we take a look at three tips and tricks to consider for successful installation:

  1. Thermal flow meter straight-run requirements
  2. Vortex flow meter installation mistakes to avoid
  3. How to select the right portable ultrasonic flow meter

Installation Tips For 3 Common Energy Flow Measurement Solutions

1. Overcoming Thermal Flow Meter Straight-Run Requirements

You have specified the correct industrial thermal insertion mass flow meter and are ready to install it within your application. Now what? Where do you place the meter for optimal performance? This is where technical expertise comes in, along with a mixture of science and tribal knowledge.

The primary installation question is: How much upstream and downstream straight run is required, and what happens if you use less straight run?

Because valves, elbows, control valves, and other piping components may cause flow disturbances, you want to select an installation site that will minimize possible distortion in the flow profile.  Check your specific piping condition against the examples shown below.

In order to achieve accurate and repeatable performance, install the flow meter using the recommended number of straight-run pipe diameters upstream and downstream of the sensor. The chart below shows basic good plumbing practice for common upstream obstructions and meter locations.

straight run pipe length requirements

What happens if you use less run than recommended?

Remember first that a thermal insertion mass flow meter probe is a “point-velocity” device and is only as good as the installation. It measures a velocity at a single point, and then the electronics multiply by the cross-sectional area to arrive at a flow rate.

The meter takes into consideration an average shape of the moving gas as it goes down the pipe. It assumes a fully-developed, bullet-shaped flow profile that is being measured at the highest velocity point at the leading edge, center.

In the case of an expansion fitting upstream (like Example 5 in the chart above), the danger is a “jet-stream” of gas shooting through the new, larger diameter section, that has not yet spread out uniformly. It is not possible to predict what will happen, nor to place a de-rated accuracy on the results. The results would most likely be noisy from the turbulent, tumbling gas. Again, it can’t be exactly predicted.

The best suggestion is to install it with 4/5 of the straight run ahead, and 1/5 after, and move the probe around, in and out, to come up with a map of the flow pattern. Hopefully, the largest flow will still be in the center, dropping off uniformly in both directions by about 15%.

Flow conditioning is the optimal solution

Another solution for insertion flow meters is to install flow conditioning plates in the flanges somewhere in the straight section, requiring three diameters of pipe run (two before, one after). This installation will totally disrupt the flow, creating a “flat” profile. The center point is now representative of the entire flow, and the meter will do a straight multiplication without accounting for a drop-off at the edges.

The best solution for constrained piping environments is to specify an inline thermal mass flow meter with integral flow conditioning elements inside the flange body. Watch this video to see how it works.

2. Vortex Flow Meter Installation Mistakes to Avoid

There are also common mistakes to avoid made when installing vortex flow meters that can affect flow accuracy and therefore affect your bottom line:

  • Not having the proper upstream and downstream diameter. Over the thousands of installations of vortex meters we have seen,  this is the number one installation problem. Unlike thermal flow meters, vortex meters do not work with flow condition plates, so they must have a straight run of pipe to function at optimal levels. In most installations, you need a straight run of at least 10 diameters upstream and 5 diameters downstream.
  • Installing the vortex meter backwards. When installing a vortex flow meter, make sure the orientation of your meter is in the direction the flow, so your meter’s flow sensor can measure your fluid accurately. Most vortex flow meters have some type of flow direction indicator to help you point downstream. Our InnovaMass iSeries, for example, has a directional pointer and arrows on the flange to help point you downstream.
  • Measuring the incorrect fluid type in the pipe. It seems like a no-brainer, but this is a more common mistake than you would think. In some situations, an end user might be measuring steam flow and think they are producing saturated steam, but in fact, they have a 50% over heat and are measuring superheated steam. With saturated steam, the pressure and temperature are linked together and move in concert together as conditions change. Whereas superheated steam has a tremendous amount of additional energy put in the steam in the form of heat. The two different flowing fluids need to be measured differently to assure accuracy.
  • Don’t shutdown your steam flow to install a vortex flow meter Many insertion vortex flow meters have a retractor to make hot tap installation much easier. This means you can install the insertion vortex flow meter in large steam pipes with no process shutdown. Watch the video to get additional hot tap installation tips for the InnovaMass 241i  insertion vortex flow meter.

3. Tips for ultrasonic flow meter installation

  •  Use Clamp-On Sensors for Field  flexibility Fieldwork calls for flexibility in your equipment. Look for a liquid flow meter clamp-on sensors with a high-powered ultrasonic pulse and digital signal processing that requires just one set of transducers for a wide range of pipe sizes and materials like metal, plastic, and concrete. These baseline features allow you to use your portable ultrasonic flow meter for many different applications, pipe sizes, and materials in your process. As a result, there is only one instrument to master for many different flow measurement need.ultrasonic.207i.content.1
  • Portable ultrasonic flow meters offer for easy set up With a portable ultrasonic flow meter, you can use one liquid flow meter in several locations throughout your flow process. Because of the portable nature of the flow meter, your equipment should all fit in one carrying case. This makes transport from one location to the next painless. Hand-held devices allow users to easily and quickly program the menu, including instantaneous flow rate, positive total, negative total, net total, velocity, date and time, and daily flow results. Wireless Bluetooth-enabled android tablet PC devices make it even easier to control data acquisition and processing.

Look for portable flow meter with a complete measuring kit including:portable ultrasonic flow meter ease of set up

  • Carrying case
  • Non-invasive clamp-on transducers with hand-held device
  • Compact mounting racks (magnetic and cable mount) and coupling compound
  • Fast set-up — 5 minutes or less! With easy set-up CD.
  • Long battery life

You’ve reached your destination and you have your equipment set up to begin taking measurements — but your flow meter is unresponsive. There’s nothing worse than dealing with equipment that doesn’t function as it should when you really need it to. To solve this common problem, look for a portable ultrasonic flow meter that includes a rechargeable lithium-ion battery that supports continuous operation for a minimum of 16 hours. You need a flow meter that can last for those long days in the field.


Have questions about Liquid Flow Meters or Switches?

We can help answer your questions about flow energy management and flow energy applications. The experts at Sierra Instruments can answer any questions you may have about ultrasonic flow meters, volumetric vortex meters, and flow switches for liquids.

Follow this link to find a local representative now and get answers to any questions you may have about our products and services.

Tame Your Energy Hog with Accurate Compressed Air Measurement

How do you tame the compressed air energy hog in your facility? As most facilities managers can attest to, the electricity used to produce compressed air can be one of the most expensive energy costs in your facility. Questions arise such as: How can I verify my compressed air capacity? How do I balance distribution and allocation in my factory? Why am I losing pressure in my lines?  The key is to have accurate compressed air flow measurement devices to gather data on your usage and create a usage profile.

In the past, facilities have used insertion turbine meters for compressed air measurement, but turbine meters don’t work well with low compressed air flows. Alternatively, insertion pitot tubes are an option, but they don’t measure direct mass flow. Both technologies are prone to clogging. Thermal mass flow meters have become the most reliable and stable devices to give you accurate compressed air measurements to conduct your audit.

Glen Coblentz, VP Sales North America for Sierra, gives some in-the-field tips to figuring out what is happening with the compressed air in your facility in his new Flow Tip Video, “Tame Your Energy Hog: Compressed Air.”

3 Tips For Understanding Your Compressed Air Usage

1. Direct thermal mass flow meter measurements are more accurate than traditional insertion turbine meters or pitot tubes.

In most facilities, compressed air usage typically varies widely throughout the day, from very heavy at times of peak manufacturing to small flows (perhaps due to leakage) when most production is on standby. With more accurate compressed air flow measurement, companies are putting a price tag on compressed air and making educated choices that lead to cost savings. In the past, most companies used volumetric, or non-compensated, flow meters, which can present challenges in compressed air measurement. For example, even a small change in operating temperature can result in these instruments showing a 5 to 10 percent reduction in accuracy.

Thermal mass flow meters, however, are ideal for compressed air audits because direct mass flow measurement is immune to changes in operating temperature and pressure. Thermal flow meters also have a very wide turndown (100:1) to handle peak and low flow fluctuations. They also have little to no pressure drop, which saves money since the facility has already paid to have the air compressed. One facility reported a $7,500 to $44,000 annual savings through improved compressed air system management and/or replacing their compressors with more energy efficient units—a substantial cost-cutting investment with relatively short-term payback.MONEY_LEAK

2.  Measure both your mass flow & pressure for a complete understanding of your compressed air usage.

To really understand what’s going on with the compressed air in your facility, you need to measure both the mass flow of your compressed air and at what pressure it’s running. If you don’t have both of these measurements, you could be venting compressed air out of your roof or have a major leak. Thermal mass flow meter devices with volume, temperature, and pressure sensors (VTP) built in will give you the mass flow rate and the pressure at the  point of measurement. Knowing both the mass flow and pressure can help you answer key questions, such as: Do I have leaks in my compressor system? Is my compressor running at capacity? Is the downstream demand too great? This valuable information could even allow you to turn off a compressor that is over-producing, saving thousands on energy bills.


3. All is not well if your pressure is dropping but the mass flow across the pipe is not changing.

If your mass flow is stays constant, but your pressure is dropping, this lets you know that your compressors can’t keep up with your downstream demand. In this case, you need to verify your compressor capacity and the compressed air allocation. The other problem with this scenario is that if your mass flow stays the same and your pressure drops, your velocity in the pipe will increase exponentially. This can cause major damage to downstream valves, as well as cause a lot of noise and discomfort to your employee. So tame that energy hog with smart, accurate, mass flow pressure measurements.

Compressed Air Management with QuadraTherm

As part of Sierra’s Big-3™ suite of Flow Energy Management products for all gas, liquid, and steam flow applications, the QuadraTherm 640i/780i thermal flow meters have been specifically designed for precise flow energy management in compressed air and natural gas applications. QuadraTherm offers:

  • Direct mass flow measurement of gases, eliminating the need for temperature or pressure compensation
  • Wide 100:1 turndown
  • Accuracy of +/- 0.5 percent reading; high flows 60,000 sfpm (0-305 smps); 100:1 turndown
  • Multivariable Mass flow rate, temperature & pressure
  • Advanced four-sensor “dry sense” technology minimizes drift and enables field validation
  • Insertion version with hot tap capability for easy installation on large pipes
  • Software applications for easy set-up, in-situ calibration, dial-a-pipe, and gas mixing
  • Digital communications suite

Browse our selection of compressed air flow meters and discover more about Sierra’s Complete Flow Energy Management Solutions for any gas, liquid, or steam flow measurement.




The Perfect Biogas Flow Measurement Solution | Sierra Instruments

Solving the Biogas Flow Measurement Conundrum

In recent years, concern about climate change has increased interest in alternative energy sources, specifically in biogas energy.

Biogas energy can be extracted from landfills. Digester gas produced at wastewater treatment plants is another common form of biogas.

So why is it so popular? In a word, economy. This otherwise wasted biogas can be used for heating, electricity, or to fuel internal combustion engines—the possibilities are endless!

This, of course, has created a demand for biogas measurement solutions. Many flow meter companies have jumped into the biogas measurement market, but not all technologies can handle this tough application.

Let’s look at why biogas measurement is so challenging and how it can be best handled.

The Challenges

Accurate flow meter measurement is critical to optimal biogas energy collection, but these factors make it difficult:

Varying compositions

This is the biggest concern and the Achilles heel for many flow meter companies. Biogas composition can vary based on the source. Biogas typically contains about 55%-65% methane, 30%-35% carbon dioxide, and some hydrogen, nitrogen and other impurities.

However, a representative compositional analysis (in volumetric percentage), shown in Table 1, shows the wide ranges in methane composition between 50%-75% and carbon dioxide between 25%-50%. This represents how the biogas composition can change over time with changing conditions in the landfill or in the digester tank.

Table 1

Most flow meters are calibrated to measure one specific gas mix composition, and sending the meter back to the factory to be recalibrated every time there’s a change isn’t very efficient. In co-generation situations, facilities managers need to be able to depend on the accurate measurement of the biogas produced—in spite of varying gas composition.

Low pressure

Low pressure makes differential pressure devices, like orifice plates, unsuitable since they require a fairly large differential pressure to operate.


Biogas is often very dirty, with a high moisture and particulate content that can clog up devices like annubars and orifice plates and gum up turbine meters and similar instruments that have moving parts.

Energy Content

Biogas produced from landfills has an additional issue: energy content. The heating value of landfill methane can be raised through adding make up natural gas as seen in the image below. But accurate flow meter measurement is critical to the process of obtaining optimal heat value.

biogas 1

Many thermal flow companies have entered this renewable energy market, but few have been able to solve these issues. Specifically, how can they make their flow meters automatically adjust for changing gas compositions?

The answer is, they can’t. The meters must be sent back to the factory for recalibration.

The Solution

Fortunately, advancements in thermal flow meter technology have not only made composition management possible, but highly accurate as well. However, few flow meter systems are available on the market today that can account for variable biogas composition.

QuadraTherm flow meters can. With an innovative design that maximizes four sensors instead of the traditional two, QuadraTherm handles this application without the need for constant recalibration.


QuadraTherm meets the criteria for successful biogas measurement by managing changes in:

  • Gas composition
  • Gas mass flow rate
  • Gas temperature
  • Gas pressure
  • Outside temperature
  • Pipe conditions (size and roughness)
  • Flow profile

A Closer Look

QuadraTherm has moved thermal insertion flow meter technology into a realm of unprecedented accuracy. Readings of +/-0.75% of reading are now possible as opposed to the 2.0% readings of older thermal technologies.

Traditional analog measurement circuits, like the Wheatstone bridge, have been replaced with more powerful, hyper-fast microprocessors that run comprehensive flow-measurement algorithms to compute mass flow.

This proprietary algorithm set serves as the “brain” of the mass flow meter, using inputs from the four sensors to solve the first law of thermodynamics for the sensor in the biogas flow stream. This allows the precise calculation of heat convected away by biogas mass flow, providing accurate mass flow measurements in a fraction of a second.

This algorithm allows management of gas composition because now recalibration is not required every time the gas changes.

qMix Gas Mixing Software

The meter can hold up to four user-customizable gas mixtures onboard and store biogas composition in a proprietary gas library, easily accessed through user software called qMix™. Engineers and operators have access to this gas library, which contains all the gas properties needed to make algorithmic gas mass flow rate calculations.

Once sampling has determined the biogas composition, operators can use qMix™ to create and name a proprietary biogas mixture. This allows operators and engineers to use just one meter with one calibration for varying gas compositions, offering a major cost savings compared to continuous sampling devices

A Money-Saving Solution

Sierra’s QuadraTherm Series of mass flow meters is the perfect solution for successful biogas measurement in any environment. By eliminating the need for frequent recalibration, QuadraTherm can save companies thousands of dollars in calibration costs, shut downs and loss of gas monetization through loss of accuracy.

Download Whitepaper on Precise Biogas Measurement 

Bringing Energy Efficiency and Cost Savings to Veteran’s Facilities

va blog image

As the infrastructure of our Veterans Affairs (VA) facilities age and government-driven energy efficiency mandates rise, VA facilities’ engineers are faced with a decision to upgrade existing equipment or replace older equipment in order to improve energy efficiency. Dealing with the upgrade or replace decision is a big one. Replacing older equipment is costly, but in the end, newer technology may integrate better into automation systems and realize even greater cost saving in energy over the long haul. What kind of data do facilities managers need to make these critical energy-saving decisions?

The Best Place To Start-Ask the Right Questions

A great place to start is by getting accurate “flow energy” measurements of the methane/natural gas, water, and steam flow in your major operations, especially in boilers and steam flow systems. Flow energy is defined as “flows that cost money,” like natural gas, compressed air, water, and steam. Since none of these commodities are “free,” VA facilities managers must strive to measure their “energy” usage accurately, determine the processes that use the most energy, and make them more efficient either by upgrading or replacing the equipment.

  1. Is your boiler running at optimal levels?
    To assess the efficiency of your boiler’s combustion, it’s critical to get accurate inlet methane measurements. Once you have accurate methane measurements, you can answer the key question: Is my boiler running too rich or too lean? If your boiler is running “rich”, which means it is using more methane than is needed for optimal combustion, you not only waste money on natural gas costs but also emit more hazardous air pollutants into our environment-every molecule of methane that is not burned increases emissions. If you’re running too “lean”, your boiler is not at optimal combustion, so you are not producing steam at capacity. Once you have determined the health of your boiler, you can either make the decision to replace your aging boiler or use measurements from thermal mass flow meters to better tune your current boiler. Learn More about Boiler Efficiency.
  2. How much steam are your boilers producing? How much steam are you allocating?
    Efficient steam production is critical for optimizing energy at Veteran Affairs facilities. The steam produced by a boiler must be measured in order to determine boiler efficiency. Accurate steam flow measurements at the production point and key allocation points will give you a true assessment of how efficient steam is running through the facility and helps identify leaks in the system. Now the question becomes what technology provides the most accurate steam flow measurement? Traditionally, steam flow has been measured with a differential pressure device. This is typically an orifice plate. However, such devices are inherently volumetric flow measurements. Changes in pressure and temperature will change the mass flow rate of steam. Even a “small” change of 10 percent in steam pressure will result in a 10 percent error in non-compensated mass flow. This means that, in a typical differential pressure measurement installation, the volumetric flow rate measured by the device must be compensated by measuring temperature and pressure, and then these three measurements (ΔP, T and P) integrated with a flow computer to calculate mass flow.
    Insertion multivariable vortex flow meters allow one instrument and one process connection to simultaneously measure mass flow rate, temperature, pressure, volumetric flow rate, and fluid density. The density of saturated steam varies with either temperature or pressure, while superheated steam varies with temperature and pressure, so multivariable vortex flow meters assure the flow meter’s density calculations are correct, and therefore, mass steam flow measurements are correct maximizing your steam productivity. Multivariable vortex flow meters provide steam accuracy of 1 percent of reading, 30:1 turndown plus pressure and temperature compensation.Again, you may need to upgrade aging steam flow infrastructure or simply tune your system with accurate steam flow measurement to save on cost and fulfill efficiency mandates.
  3. How much water are you using for key processes?
    In boiler tuning, the feedwater flow to the boiler is an important measurement, since you need to measure the efficiency at which the boiler turns this feed water into steam.  You may also need to measure the thermal/BTU energy.  A clamp-on ultrasonic flow meter is ideal for this type of water measurement due to high accuracy at low and high flows, installation with no pipe cutting or process shutdown, and immunity to external noise. Coupled with temperature sensors on the “hot” and “cold” legs, the thermal energy gained or lost can be measured. This thermal/BTU measurement is critical for optimizing central heating and cooling systems that provide HVAC to the entire facility.

Big-3 Eases the Burden of Recommissioning  

To address the flow measurement of the methane, steam, and water for such a large scale equipment upgrade, Veteran Affairs facility managers would typically work with up to 5 different companies with varying technologies to get these critical flow energy measurements. Imagine only working with one supplier for all of your gas, liquid and steam flow measurements. Sierra provides flow experts and Big-3 technology for all gas, liquid, and steam flow measurements. The Big-3 includes:

  • QuadraTherm 640i/780i, the most accurate thermal flow meters on the market for methane and air flow measurement
  • Insertion mulitvariable InnovaMass 240i/241i vortex flow meters for steam flow measurements-easy hot tap installation
  • Clamp on InnovaSonic 207i ultrasonic water flow meters with energy/BTU capability
  • Specialized, local support team for all three technologies
  • Shared software applications and operating system for easy integration
  • Designed, built, and calibrated in the USA by Sierra

Learn more about Flow Energy Measurement of All gas, liquid, steam flow.

Watch Flow Energy Management Videos


Tune Your Boiler: Watch Video for 3 Tips to Improve Energy Efficiency

Improving energy efficiency in facilities, campuses and hospitals is top of mind for most facilities managers and engineers.  Government regulations like Boiler MACT and other energy efficiency mandates for government buildings like VA hospitals have put the pressure on facilities engineers to take a hard look at their equipment to optimize for energy efficiency.  Optimizing energy efficiency comes in the form of both saving energy and increasing productivity.  Hands down the biggest energy hog in a facility is compressed air production and a close second are the boilers which use methane & air for combustion to create steam energy.

Glen Coblentz, VP Sales North America for Sierra, tackles the tough question, “Is Your Boiler Running at Optimal Levels?” and gives some in the field tips to tuning your boiler to improve energy efficiency in his new Flow Tip Video. Watch Video.

3 Tips for Tuning Your Boiler

1. Know Your Flow-get accurate methane measurements in low and high flow conditions
As with most energy audits, it’s critical to know how much fluid you have running in your pipe. In this case, you must know much inlet methane (or intake fuel) is entering your boiler? This is actually a difficult flow measurement due to the requirement for flow measurement accuracy over a wide range, from very low flows to high flows. There are many types of flow technologies to choose from for methane measurement.

In the past, facilities have used insertion turbine meters for methane measurement, but turbine meters don’t work well with low flow conditions.  Thermal flow meters are the ideal technology for methane measurement due to their high accuracy over a wide range-from 0 up to 60,000 sfpm  (0 to 305 smps) and wide 100:1 turndown.

2. Get direct mass flow measurements over volumetric flow rate
We have established that thermal flow meters have excellent accuracy and turn down over a wide range. But what are the other advantages of using thermal flow meters for methane measurements? Thermal mass flow meters are ideal for natural gas combustion because mass flow rate, not volumetric, is the quantity of direct interest. For example, the optimal fuel/air ratio for efficient combustion is calculated on a mass basis.

Natural gas is also billed on a mass basis. Because thermal mass flow meters count the molecules of gas, they are immune to changes in inlet temperature and pressure. In a thermal flow meter’s simplest working configuration, fluid flows past a heated thermal sensor and a temperature sensor. As the molecules of the fluid flow pass the heated thermal sensor, heat is lost to the flowing fluid. The thermal sensor cools down, while the temperature sensor continues to measures the relatively constant temperature of the flowing fluid.

3. Determine if your boiler is running too rich or too lean 
Once you have accurate methane measurements, you can answer the key question: Is my boiler running too rich or too lean? If your boiler is running “rich”, which means it is using more methane than is needed for optimal combustion, you not only waste money on natural gas costs but also emit more hazardous air pollutants into our environment-every molecule of methane that is not burned increases emissions. If your running too “lean”, your boiler is not at optimal combustion, so you are not producing steam at capacity.

So the answer is to “tune” your boiler to get the optimal boiler efficiency calculation which improves energy efficiency.  A well-tuned boiler is around 80% efficient. If the boiler’s efficiency is less than 80%, then energy is being wasted.  Government regulations like Boiler MACT require end users to fix the boiler to meet this efficiency level. “Fixing it” entails fixing leaks, adding insulation, and cleaning heat exchanger tubes, which all add to the cost of boiler maintenance. Download Boiler MACT Information Guide.

Boiler Tuning with Thermal Mass Flow Meters

As part of Sierra’s Big-3™ suite of Flow Energy Management products for all gas, liquid, and steam flow applications,  QuadraTherm 640i/780i thermal flow meters have been specifically designed for precise flow energy management in compressed air and natural gas applications. QuadraTherm offers:

    • Direct mass flow measurement of gases, eliminating the need for temperature or pressure compensation
    • Wide 100:1 turndown
    • Accuracy of +/- 0.5 percent reading; high flows 60,000 sfpm (0-305 smps); 100:1 turndown
    • Multivariable Mass flow rate, temperature & pressure
    • Advanced four-sensor “dry sense” technology minimizes drift and enables field validation
    • Insertion version with hot tap capability for easy installation on large pipe
    • Software applications for easy set-up, in-situ calibration, dial-a-pipe, and gas mixing
    • Digital communications suite

For a more economical solution, Sierra’s BoilerTrak 620s provides direct mass flow accuracy at a lower price point. Sierra also offers all products needed for Boiler tuning like the InnovaSonic 207i ultrasonic flow meter to measure the feedwater and InnovaMass 241i for measuring steam output. Learn more about our complete flow energy management solution for all gas, liquid and steam flow applications.

See all of Sierra’s boiler efficiency solution flow meters.



Thermal Mass Flow Meters Increase Boiler Efficiency in Co-generation Applications

Did you know most chemical plants use electricity derived from an on-site natural gas power plant or co-generation plant burning waste gas streams? 

In large boilers, power plants bring together air and fuel (natural gas, waste gas, oil or coal) for combustion, which creates heat. The heat boils the water, creating steam. The steam runs through a turbine, which causes the turbine to spin, thus generating electricity. Measuring the flow energy — flows that cost money such as natural gas, waste gas, water and steam — in these boiler applications is critical for improving energy efficiency, identifying waste and minimizing the greenhouse gases going into atmosphere. Only with accurate mass flow measurement can you make informed decisions to improve energy efficiency. Therefore, to improve boiler efficiency  it’s critical to know your options when selecting the appropriate flowmeter technology to measure natural gas, water and steam in power generation . 

Increasing Combustion with Optimal Fuel-to-air Ratio

Power generation requires inlet air and fuel (natural gas, waste gas, oil or coal) for combustion. Engineers must measure the air and gas ratio accurately for efficient combustion in the boilers. Too much gas is wasteful, dangerous and costly, and too little will create insufficient flame to boil the water efficiently.

Choosing the Right Meter to Monitor Fuel-to-air Ratio

Orifice and Turbine Meters. Monitoring fuel gas to boiler units traditionally is accomplished with an orifice or turbine meter. However, these are not the best measuring devices for this application because they both are subject to failure and require frequent skilled maintenance to provide an accurate and reliable measurement.

Constrained piping conditions can also give engineers headaches. For example, an orifice meter requires 10 to 50 diameters of upstream piping to eliminate the effect of flow disturbances. Because long straight pipe runs are hard to find, most flow measurement systems are affected adversely by varying flow profiles within the pipe.

The biggest cause for concern, however, is that orifice and turbine meters measure volumetric flow. Additional pressure, temperature and differential pressure sensors, as well as a flow computer, are required to calculate or infer mass flow. This not only degrades the flow measurement accuracy, but the installation and maintenance costs with this type of compensated measurement increase the cost of ownership.

Thermal Mass Flow Meters. In contrast, thermal mass flowmeters are suitable for the direct mass flow measurement of gases, not volumetric flow. Because thermal mass flowmeters count the gas molecules, they are immune to changes in inlet temperature and pressure and measure mass flow directly without compensation. In inlet air and gas flow boiler applications, thermal flowmeters perform well because the optimal fuel-to-air ratio for efficient combustion in boilers is calculated on a mass basis, not volumetric (Figure 3).

In a thermal flow meter’s simplest working configuration, fluid flows past a heated thermal flow sensor and a temperature sensor. As the fluid’s molecules flow past the heated thermal sensor, heat is lost to the flowing fluid. The thermal sensor cools down, while the temperature sensor continues to measure the flowing fluid’s relatively constant temperature. The amount of heat lost depends on the fluid’s thermal properties and its flow rate. Thus, by measuring the temperature difference between the thermal and temperature sensors, the flow rate can be determined. 

New developments in four-sensor thermal technology coupled with stable “dry sense” sensor technology as well as advanced thermodynamic modeling algorithms enable some thermal flowmeters to attain ±0.5% reading accuracy, rivaling Coriolis flow meter accuracy at less cost. On-board software apps also enable gas-mixing capability, in-situ validation, and dial-a-pipe.


Case-in-Point. Purified Terephthalic Acid (PTA) in China uses Sierra’s thermal mass flow meters to improve boiler efficiency, cut costs and meet government regulations.

Purified terephthalic acid (PTA) is the precursor to polyethylene terephthalate (PET), the ubiquitous material used worldwide in plastic bottles, textiles and elsewhere. A PTA chemical plant in China generated steam and electricity from its on-site power plant using coal as a fuel. It also had a wastewater treatment station that produced methane, which then was flared off. Both processes are major greenhouse gas emitters.

New government regulations required the company to reduce its CO2 emissions. The plant decided to modify its four boilers to burn both coal and the previously flared-off waste gas (methane), estimating a savings of approximately $0.5 million in coal each year. Working with a single-source supplier, engineers reworked the boilers’ designs and installed Sierra Instruments’ industrial insertion thermal mass flowmeters to measure its combustion air and waste gas fuel, ensuring optimal combustion (Figure 7).

One thermal flowmeter measures the waste gas flow, while the other four thermal flowmeters provide sub-metering of this gas stream to each boiler. Another four meters measure pre-heated (200°C, 392°F) combustion air to each boiler, allowing the boiler control system to optimize the fuel-to-air ratio. The Sierra mass flow meters provided both precision flow data for complying with government regulations and helped the company reduce waste while increasing efficiency.

Discover More Ways to Improve Boiler Efficiency through Tuning your boiler  https://www.sierrainstruments.com/blog/?tuning-boiler-epa-boiler-mact-compliance.