Book contents
- Front Matter
- Contents
- Preface
- Acknowledgments
- Nomenclature
- Chapter 1 Introduction
- Chapter 2 Fluid Mechanics Essentials
- Chapter 3 Specification, Selection, and Audit
- Chapter 4 Calibration
- Chapter 5 Orifice Plate Meters
- Chapter 6 Venturi Meter and Standard Nozzles
- Chapter 7 Critical Flow Venturi Nozzle
- Chapter 8 Other Momentum-Sensing Meters
- Chapter 9 Positive Displacement Flowmeters
- Chapter 10 Turbine and Related Flowmeters
- Chapter 11 Vortex-Shedding, Swirl, and Fluidic Flowmeters
- Chapter 12 Electromagnetic Flowmeters
- Chapter 13 Ultrasonic Flowmeters
- Chapter 14 Mass Flow Measurement Using Multiple Sensors for Single- and Multiphase Flows
- Chapter 15 Thermal Flowmeters
- Chapter 16 Angular Momentum Devices
- Chapter 17 Coriolis Flowmeters
- Chapter 18 Probes for Local Velocity Measurement in Liquids and Gases
- Chapter 19 Modern Control Systems
- Chapter 20 Some Reflections on Flowmeter Manufacture, Production, and Markets
- Chapter 21 Future Developments
- Bibliography
- A Selection of International Standards
- Conferences
- References
- Index
Chapter 15 - Thermal Flowmeters
Published online by Cambridge University Press: 22 September 2009
- Front Matter
- Contents
- Preface
- Acknowledgments
- Nomenclature
- Chapter 1 Introduction
- Chapter 2 Fluid Mechanics Essentials
- Chapter 3 Specification, Selection, and Audit
- Chapter 4 Calibration
- Chapter 5 Orifice Plate Meters
- Chapter 6 Venturi Meter and Standard Nozzles
- Chapter 7 Critical Flow Venturi Nozzle
- Chapter 8 Other Momentum-Sensing Meters
- Chapter 9 Positive Displacement Flowmeters
- Chapter 10 Turbine and Related Flowmeters
- Chapter 11 Vortex-Shedding, Swirl, and Fluidic Flowmeters
- Chapter 12 Electromagnetic Flowmeters
- Chapter 13 Ultrasonic Flowmeters
- Chapter 14 Mass Flow Measurement Using Multiple Sensors for Single- and Multiphase Flows
- Chapter 15 Thermal Flowmeters
- Chapter 16 Angular Momentum Devices
- Chapter 17 Coriolis Flowmeters
- Chapter 18 Probes for Local Velocity Measurement in Liquids and Gases
- Chapter 19 Modern Control Systems
- Chapter 20 Some Reflections on Flowmeter Manufacture, Production, and Markets
- Chapter 21 Future Developments
- Bibliography
- A Selection of International Standards
- Conferences
- References
- Index
Summary
INTRODUCTION
There are broadly two concepts of thermal flowmeter now available for gas mass flow measurement, one of which is also applicable to liquids. I shall follow the useful terminology in ISO committee draft (ISO/CD 14511:1998) for the two types. The first is the capillary thermal mass flowmeter (CTMF), which has broad applications in the control of low flows of clean gases, but which can also be used with a bypass containing a laminar element to allow higher flow rates to be measured. The arrangement of heaters and coils between the various manufacturers differs, but the basic approach is the same, with heat added to the flowing stream and a temperature imbalance being used to obtain the flow rate.
The second is the full-bore thermal mass flowmeter (ITMF), which is available as both insertion probe and in-line type. It has a widely used counterpart in the hot-wire anemometer for measurement of local flow velocity, but, as the need for a gas mass flowmeter has become evident, it has been developed as a robust insertion probe for industrial usage and then as the sensing element in a spool piece flowmeter. It has been produced by an increasing number of manufacturers in recent years as a solution to the need for such a mass flowmeter.
CAPILLARY THERMAL MASS FLOWMETER – GASES
In various examples of the CTMF, the gas flows through a very small diameter tube that has heating and temperature-measuring sensors.
- Type
- Chapter
- Information
- Flow Measurement HandbookIndustrial Designs, Operating Principles, Performance, and Applications, pp. 371 - 390Publisher: Cambridge University PressPrint publication year: 2000