Thermal Mass Flow Meters

Get Accurate and Repeatable Measurements with Sierra Thermal Mass Flow Meters

With North America's #1 selling thermal mass flow meter (Flow Research, Boston, MA), customers can enjoy the many benefits of thermal technology. These advantages include wide turndown ratio, very low pressure drop, no moving parts, application flexibility, and a direct digital gas mass flow rate measurement. Sierra's 640i/780i and 640S/780S thermal flow meters deliver long-term stability with patented no-drift DrySense™mass flow velocity sensor. These sensors allow for reliable In-Situ Calibration Validation backed by a lifetime sensor warranty.

Watch Video: How Thermal Mass Flow Technology Works

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What Are the Benefits of a Thermal Mass Flow Meter? 

  • Application Flexibility: A thermal mass meter is suitable for a wide range of applications, whether you’re looking for specific gas measurements or need a thermal air flow meter. 

  • Direct Digital Gas Mass Flow Measurement: Sierra’s thermal flow meters measure mass flow, allowing you to avoid the pressure and temperature compensations needed with volumetric flow measurements.

  • Wide Turndown Ratio: Sierra’s thermal mass flow meters feature turndown of up to 1000:1, allowing you to measure both very low and very high flows with a single instrument. 

  • Very Low Pressure Drop:  Thermal mass flow meters demonstrate negligible pressure drop, making them a leading choice for a wide range of pipe and duct sizes.

  • No Moving Parts: Thermal flow meters are easier and less costly to maintain than flow meters with moving parts and can easily be installed via hot tap.

Reduce Operation Cost with Precision Thermal Mass Flow Measurement

Sierra manufactures a wide variety of inline and insertion thermal mass flow meters.  These meters are used for precision CFM (cubic feet per minute) measurement of gas mass flow rate in light and heavy industrial applications.  Our proprietary DrySense sensor is key to our thermal meter stability and offers customers:

  • Immunity to cracking and shifting of the sensor over time
  • Maximum sensitivity, reproducibility
  • Ultimately greatly improved CFM air flow meter accuracy
 

Sierra Certifications and Calibrations 

Boiler MACT Certified

Thermal mass flow meters are also ideal for compliance for Boiler MACT regulations for inlet fuel measurement for:

  • Area source boilers (40 CFR 63, subpart JJJJJJ)
  • Major source boilers (40 CFR 63, subpart DDDDD)

National Institute of Standards and Technology (NIST) Calibrations

Calibrations are crucial for accurate thermal flow meters. These meters should be calibrated on a closed-loop gas calibration system traceable to a national standards lab. Sierra uses a cutting-edge, NIST-traceable calibration system to calibrate each thermal flow meter to the exact gas, temperature, and pressure conditions of the customer. 

The Sierra Difference

  • Localized and Global Support: Sierra has technical support staff around the world able to help answer your application and product questions.  Our Field Service Engineers can also come directly to you and help with a wide range of field service needs.

  • Commissioning: Sierra’s team of certified Field Service Engineers offer commissioning, training, troubleshooting, calibration, and repair services directly in the field.

  • Lifetime Support: The Sierra support team is here for your product and application needs via our tech support hotline and on-site visits.


Looking for the best gas flow meter on the market? Sierra's QuadraTherm mass flow meter is the most accurate thermal flow meter in the world.

Due to its special sensor design and proprietary Flow Engine, QuadraTherm is now the only thermal flow meter that can be field-updated with new gas compositions without sending the meter back to the factory.

FAQS

Q: How do thermal mass flow meters work? 

A: Sierra’s traditional industrial thermal mass flow meters work using two sensors: a temperature sensor that monitors the temperature of the flowing gas and a heated sensor (or velocity sensor) that is heated to maintain a predefined temperature differential. The amount of heat required to maintain the constant temperature differential is directly proportional to the cooling effect of the gas molecules flowing by. This allows the sensor to calculate a mass flow measurement.Sierra’s QuadraTherm thermal mass flow meter four-Sensor thermal technology provides critical sensor inputs to a proprietary qTherm heat transfer algorithm set to instantly calculate gas mass flow rate at very high accuracies.  The innovative new sensor mechanical design coupled with qTherm provides accuracy-never before possible with thermal technology.
 

Q: What makes mass flow measurement more reliable than volumetric flow measurement? 

A: Mass flow measurement is more reliable than volumetric flow measurement because the former does not require additional compensation for pressure or temperature changes. Gases are susceptible to temperature and pressure changes that impact the volume of that gas flowing through a pipe or duct. In such a case, a volumetric meter calibrated under one set of pressure or temperature conditions will not give an accurate reading if those conditions change. A mass flow meter, on the other hand, measures the number of molecules in a pipe or duct rather than the space those molecules take up. As such, a mass flow measurement is not thrown off by pressure or temperature fluctuations. 

Useful Thermal Flow Meter Resources

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QuadraTherm® 640i

Industry's Most Accurate Air / Gas Thermal Insertion Mass Flow Meters

  • Achieve high accuracy +/- 0.75% of reading
  • Eliminate drift with patented DrySense™ sensor
  • Validate in the field for easy in-situ calibration
  • Use qMix software to easily change gas composition in the field and retain accuracy Download Flare Gas Mass Measuring Tech Note
  • Backed by lifetime sensor warranty
  • Boiler MACT certified for area source boilers (40 CFR 63, subpart JJJJJJ) and for major source boilers (40 CFR 63, subpart DDDDD) Learn more > 
  • Part of Sierra's Big-3 iSeries family of flow meter technologies Learn more >
  • Meet EPA rule 40 CFR 63 for flare gas measurement at ultra-low flows down sfps (0.03 smps) with QuadraTherm® qMix RealTime Flare Measurement System (FMS)
QuadraTherm® 780i

Highest Air/Gas Mass Flow Measurement Accuracy in Industry

  • Achieve the highest accuracy +/- 0.5% of reading
  • Eliminate drift with DrySense sensor
  • Reduce straight-run requirements with built-in flow conditioning
  • Needs only 1-diameter up and zero downstream diameters
  • Validate in the field for easy in-situ calibration
  • Backed by lifetime sensor warranty
  • Boiler MACT certified for area source boilers (40 CFR 63, subpart JJJJJJ) and for major source boilers (40 CFR 63, subpart DDDDD), Learn more > 
  • Part of Sierra's Big-3 iSeries family of flow meter technologies, Learn more >
  • Meet EPA rule 40 CFR 63 for flare gas measurement at ultra-low flows down sfps (0.03 smps) with QuadraTherm® qMix RealTime Flare Measurement System (FMS)
TM500™

High Performance Industrial Thermal Mass Flow Meter

  • Accuracy 
    • +/- 1.0% of reading plus +/- 0.2% of full-scale – Air, Nitrogen 
    • +/- 1.5% of reading plus +/- 0.5% of full-scale – All other gases
  • Repeatability +/- 0.2% of full scale
  • Direct measurement of gas mass flow / No volume to mass calculations
  • DigiSense™ robust sensor design
  • AC or DC power 
  • Use optional Gas-Mix™ feature to easily change gas selection or create gas mixes in the field - no recal required 
  • 2-3 week delivery lead times / 1 week delivery possible
TM100™

Economical Industrial Thermal Mass Flow Meters

  • Accuracy 
    • +/- 1.0% of reading plus +/- 0.2% of full-scale – Air, Nitrogen 
    • +/- 1.5% of reading plus +/- 0.5% of full-scale – All other gases
  • Repeatability +/- 0.2% of full scale
  • Direct measurement of gas mass flow / No volume to mass calculations
  • DigiSense™ robust sensor design
  • 12 to 24 volt DC power 
  • Use optional Gas-Mix™ feature to easily change gas selection or create gas mixes in the field - no recal required  
  • 2–3-week delivery lead times / 1-week delivery possible
BoilerTrak 620S-BT

Insertion Thermal Mass Flow Meter for Boiler & Heater Efficiency

  • Optimized natural and propane measurement for 1, 2, 3, 4 inch sch. 40 pipe sizes
  • Wide flow ranges from 0 to 42,000 scfh
  • Easily install in the field or retrofit
  • Certified for GHG measurement meeting EPA (40 CFR Part 98)
  • Boiler MACT certified for area source boilers (40 CFR 63, subpart JJJJJJ) and for major source boilers (40 CFR 63, subpart DDDDD) Learn More
BioTrak™ 645i/745i 

Wastewater Dedicated Thermal Mass Flow Meter

  • Field-Selectable Gases-air, methane, digester gas 
  • Direct mass flow measurement maintains precise control of aeration, digestion, and cogeneration 
  • Accuracy: Air: +/-1% of reading +/-0.2% of full scale  - Other gases: +/-1.5% of reading +/-0.5% full scale 
  • Insertion and inline versions
  • AC or DC power input available 
  • Optional hot top packing gland and retractor 
  • Integral and remote electronic configurations available 
  • Wide measurement range up to 1000:1 turndown; 100:1 typical 
  • BioCal Calibration Validation within five minutes  
FastFlo 620S

Fast-Response Insertion Thermal Mass Air Flow Sensor

  • Increase efficiency with fast response time within 200 milliseconds
  • Optimized air, nitrogen, and inert gas measurement for 1, 2, 3, 4 inch sch. 40 pipe sizes
  • Wide flow ranges from 0 to 42,000 scfh
  • Easily install in the field or retrofit
SteelMassTM 640S

Insertion Gas Mass Flow Meter

  • Insertion, totalizing air/gas mass flow meter
  • Eliminate drift with patented DrySense™ sensor
  • Increase flexibility with low pressure drop, high turndown
  • Validate in the field for easy in-situ calibration
  • Backed by lifetime sensor warranty
qMix Gas Mixing Feature

Field-Update For Gas Composition Changes

  • Powerful, gas mixing software to create custom gas mixtures in the field
  • Per meter license gives unlimited custom gas mixtures and uploads per meter serial number
  • Maintain flow meter accuracy if gas composition changes
  • No need to send unit back to the factory if gas composition changes
  • Avoid costly recalibration
FlatTrak 780S

Inline Thermal Mass Flow Meters with Flow Conditioning

  • Reduce straight-run requirements with built-in flow conditioning
  • Eliminate drift with DrySense sensor
  • Needs only 3-diameters up, zero downstream
  • Validate in the field for easy in-situ calibration
  • Backed by lifetime sensor warranty
FlatTrak 780S-UHP

Industry-Choice For Bulk High Purity Gas Custody Transfer To Semicon Fabs

  • Optimized for bulk ultra high purity (UHP) gas custody transfer
  • Direct mass flow measurement
  • No moving parts, 100:1 turndown, low pressure drop
  • Reduce straight-run requirements with built-in flow conditioning
  • Validate in the field for easy in-situ calibration
Flow Totalizer

Four Multi-Gas Flow Totalizers for the QuadraTherm Thermal Mass Flow Meter

  • View and totalize four gases with one instrument
  • Totalize multiple gases independent of each other
  • Accurately monetize and allocate gas usage
Measure Flare Gas in Real Time

QuadraTherm® qMix RealTime
Flare Measurement System

  • Meet EPA rule 40 CFR 63-measure flare gas down to 0.1 sfps (0.03 smps) where ultrasonic flow meters can't operate
  • Handles upset conditions at ultra-high flows with wide 1000:1 turndown
  • Easy to install with current ultrasonic flow meters-no process shutdown
  • Use qMix RealTime App to connect, read, and update new flare gas composition from a GC-real time, no recalibration needed
  • Set update frequency by time or by percentage change in the gas composition
  • Get flow and composition trend analysis, flow alarming and triggers
BioTrakTM 645S/745S

Wastewater Thermal Mass Flow Meter

  • Direct mass flow measurement maintains precise control of aeration, digestion, and cogeneration
  • Microprocessor based, field-programmable electronics
  • Wide measurement range up to 1000:1 turndown; 100:1 typical
  • DigiSense sensor design / Swivel probe ±180° into four positions
  • BioSelect™ menu provides field selectable air, methane, and digester gas
  • BioView™ software provides access to meter data / Configure meter settings in field
  • BioCal™ verifies calibration within five minutes

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