The Significance of Thermowells

Consider relevant factors and standards

Thermowell Drawing

Thermowell Drawing
Courtesy ISA InTech

Online — In a May/June 2013 article in InTech Magazine Basics of thermowell design and selection”, author Ehren Kiker describes why thermowells are important and how their key parameters can be determined for a particular use situation.

The article begins:

“When planning for a temperature measurement application, a fair amount of consideration is typically given to sensor selection (e.g., thermocouple vs. RTD) and wiring of the output (e.g., transmitter vs. direct wiring), and how these factors will affect the measurement. Often, by comparison, relatively little consideration is given to the mechanical components of the sensor assembly, particularly the thermowell.

“Of all the components in a typical temperature assembly, a thermowell would seem to be the simplest and least critical. In reality, the thermowell is fundamentally important because it directly and significantly affects the life span of the sensor and accuracy of the measurement. It also protects the closed process, providing plant and personnel safety.”

Click here to read the full article now.

ABOUT THE AUTHOR

Ehren Kiker (ehren.kiker@us.endress.com) is a product manager with Endress+Hauser with more than 15 years of experience in process control instrumentation.

Intech MagazineInTech Magazine provides the most thought-provoking and authoritative coverage of automation technologies, applications, and strategies to enhance automation professionals’ on-the-job success.

There is much more online at: https://www.isa.org/standards-and-publications/isa-publications/intech-magazine/.

About ISA

The International Society of Automation (www.isa.org) is a nonprofit professional association that sets the standard for those who apply engineering and technology to improve the management, safety, and cybersecurity of modern automation and control systems used across industry and critical infrastructure.\

Wake Frequency Calculator by TempSens Instrument

Plus two additional Calculators

Wake_Frequency_CalculatorAn online resource calculator for estimating the Wake Frequency of a thermowell in a flowing stream.

According to the website:

“TEMPSENS WAKE FREQUENCY CALCULATOR is easy to use and it also ensures that thermowell is designed within the dimensional limits of PTC19.3, 2010. This calculator establishes the practical design considerations for Thermowell installations in power and process piping, which also incorporates the latest theory in the areas of natural frequency, Strouhal frequency, in-line resonance and stress evaluation.”

The same webpage provides a Temperature Calculator to convert the Emf (mV)/Ohms generated by thermocouple & RTD to the temperature or vice versa as well as a SPRT Calculator to provide the ITS-90 coefficients for the set of resistance readings provided on the fixed point cell.

Multilingual Humidity Calculator Online

From E+E Elektronik

humidity-calculator

Multilingual Humidity Calculator Online at E+E Elektronik’s website

The humidity calculator from E+E Elektronik is used for the rapid conversion of humidity measurements.

Uniquely, the humidity calculator also includes measurement uncertainties in the calculation.

The humidity calculator can be used online using your favorite Web browser. Thus, it does  not require any program to be installed on a PC.

Or, http://www.epluse.com/fileadmin/Humidity_calculator/EEHumidityCalculator.swf

An Explanation of humidity calculator measurements is found here. But it is more than a simple help page it is, as entitled on the E+E Electronik website “Explanation of humidity calculator measurements”, with a definition or description of each term and the appropriate measurement units and commonly used symbol for them .

About E+E Electronik

E+E Elektronik Develops and produces sensors for measurement of relative humidity, CO2, air velocity and mass flow. It also is passionate about development and production of humidity calibration systems, so much so that E+E Elektronik as a “designated laboratory” is commissioned to provide and further develop the national etalon for humidity and air velocity for Austria.

E + E Elektronik Ges.m.b.H
Langwiesen 7
A-4209 Engerwitzdorf
Austria

T: +43 7235 605-0
F: +43 7235 605-8
E: info@epluse(dot)com
W: www.epluse.com

Multiple Sensor Type Vendors

There are numerous distributors who sell many temperature sensor products and accessories, among other things. Some manufacturers specialize in producing a significant number (usually three or more) of different types of temperature sensors and sell to either a distributor network or directly to the public by Internet and/or Catalog sales (telephone or mail).

Start your search either here for vendors of multiple types or, if you are seeking a specific type, go to the vendor page index or directly to a page describing sensor types; you can find the vendors of specific types from many different places there.

When all else seems to have failed, try our built-in search engine – see text box input  above.

But if that fails to help you find what you need, try our more extensive, free directory website TempSensor.net. It is not maintained as often as this site, but may have what you seek.

  1. Chaney Instruments, Inc (USA)
    Their full line of NSF-certified, professional-quality kitchen thermometers have something for every application: refrigeration, freezing, deep-frying, meat preparation and milk frothing as well.
  2. Cole-Parmer (USA)
    All kinds of laboratory thermometers including pocket bimets.
  3. W. H. Cooke & Co., Inc.(USA)
    A thermocouple manufacturer that specializes in specialty thermocouples and related temperature indicators and controllers for the Baking Industry. Also a manufacturers rep for other instrumentation; in Maryland .
  4. EDL, Inc,(USA)
    Temperature sensors, RTDs, TCs, thermometer pyrometers – also offer a wide range of value-priced temperature indicators and related specialty products.
  5. ETI Ltd (UK)
    Electronic Temperature Instruments, probes and accessories, including  Differential Digital thermometer, thermo-hygrometer & timber building moisture meters..
  6. Electrical & Electronics Corporation (India)
    Process Control Instrumentation Sensors and Accessories, e.g. Thermocouples, RTD’s, Cables & Thermowells
  7. Exacon (Denmark)
    Pages of medical temperature sensors
  8. JMS Southeast (USA)
    Statesville ,North Carolina, …. TC maker and supplier of all kinds of temperature sensors to industry and commerce.
  9. Kobold Instruments, Inc. -
    Temperature Switches, Temperature
  10. Minco Products., (USA)
    Manufacturers of thermocouples, RTDs and more in Minneapolis MN,
  11. Omega Engineering(USA)
    The mega Catalog and web vendor of temperature and other sensors with offices and websites in England, Germany and elsewhere.
  12. Palmer Instruments Inc.(USA)
    Specializing in Glass Thermometers, but covering a wide array of products. Part of the Instrumentation Group that includes Wahl Instruments, noted for its IR Thermometers.
  13. PCE Instruments(Germany)
    PCE Instruments offers a broad range of products from the field of measuring instruments. Here you can find all various types of testing and measuring instruments, handheld and desktop
  14. Peak Sensors (UK)
    A relatively new company specialising in the manufacture of TCs, RTDs, Thermowells, and platinum sheathed sensors for the glass industry. Also supply associated equipment such as ceramics and other components.
  15. Pentronic (Sweden)
    A leading supplier of temperature measurement equipment in Scandinavia for industry, research and education. Manufactures primarily Pt 100 and thermocouple elements. Their calibration laboratory is accredited.
  16. Philadelphia Instruments and Controls, Inc.(USA)
    Specializes in the production of temperature related products, such as liquid-in-glass thermometers-specialty units for candy making & more. A most interesting website especially the “DID YOU KNOW?” list of historic thermometer facts .
  17. Precon, Inc. (USA)
    NTC Thermistors, RTDs, and Humidity Sensors available in standards or custom probes. Precon also designs and builds controllers and can provide turnkey sensing and control solutions
  18. Tech Instrumentation (USA)
    Tech Instrumentation offers a extensive variety of temperature measuring instrumentation from inexpensive bi-metalic and glass thermometers to rugged, precise industrial thermometers.
  19. ThermoWorks (USA)
    New outlet for fast digital Thermometers, Type K thermocouples, digital meat thermometers, thermistor sensor probes, temperature loggers, TC probes, IR thermometers, HACCP thermometers and more.

Thank you for visiting!

FLIR SYSTEMS, INC.

 With many offices throughout the world

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FREE R&D Handbook

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About FLIR Systems

FLIR Systems, Inc. is a world leader in the design, manufacture, and marketing of sensor systems that enhance perception and awareness.

FLIR’s advanced systems and components are used for a wide variety of thermal imaging, situational awareness, and security applications, including airborne and ground-based surveillance, condition monitoring, navigation, recreation, research and development, manufacturing process control, search and rescue, drug interdiction, transportation safety, border and maritime patrol, environmental monitoring, and chemical, biological, radiological, nuclear, and explosives (CBRNE) threat detection.

For more information, visit FLIR’s web site at www.FLIR.com and their more complete list of offices at: www.flir.com/cs/emea/en/view/?id=42306

Continue reading

Thermocouple Junctions Are Not Voltage Sources!

by R. P. Reed, Ph.D, PEret

NOTE: The following is a brief overview of a special article written and published here by a noted authority on thermocouples. Dr. Ray P. Reed. Dr. Reed is a retired researcher from Sandia Laboratories in New Mexico, USA.

He is a semi-retired, yet still a contributing member of the ASTM International Committee E20 on Temperature Measurement. He has written and presented many professional and peer-reviewed articles on temperature sensors, notably thermocouples in his long career.

His list of publications is on another page on this website, http://www.temperatures.com/resources/temprefs/publications-presentations-of-r-p-reed/.

This new article from R.P. Reed is published with his permission and is in downloadable format.

It is in Adobe PDF format and its size is about 310 kb.

Here’s a sample of the initial paragraph of the article:

“Thermocouples, based on the Seebeck effect, remain the simplest, most widely used, electrical sensor of temperature. Thermocouples consist only of thermoelectrically dissimilar conductor legs connected at junctions. The Seebeck emf occurs only in the legs. Therefore, commonplace calibration and thermometry errors relate to degraded thermoelements, not to junctions. A yet commonplace implicit Junction-Source Model incorrectly asserts that Seebeck emf occurs only in junctions. That erroneous concept hides problems that are commonplace in consequential thermometry.”

Link to a full Introduction to the article and the download link Link: http://www.temperatures.com/thermocouples are not voltage sources!/

TI Temperature Measurement Videos

TI, or Texas Instruments, is one of the world’s most prolific and largest makers of temperature sensors. They make all kinds but their sensors are mostly in the form of Integrated Circuit semiconductors.

TI also does an exceptional job in educating users how their devices work and how they can be interfaced and incorporated in measurement systems. Especially useful are the videos showing how some of their other integrated circuit modules can be used with external temperature sensors, like Thermocouples, RTDs and Thermistors.

Here’s an example of an interesting one:

Developed through TI’s expertise in MEMS technology, the TMP006 is the first of a new class of ultra-small, low power, and low cost passive infrared temperature sensors. It has 90% lower power consumption and is more than 95% smaller than existing solutions, making contactless temperature measurement possible in completely new markets and applications.

Check out their Video Channel on YouTube, especially the long list of videos already published about “Temperature Measurement”. It very straightforward; just go to: https://www.youtube.com/user/texasinstruments/search?query=%22temperature+measurement%22

Acoustic Gas Thermometry Review Article

Metrologia Cover Image

Metrologia Cover Image

Online  —  Acoustic gas thermometry (AGT) is not a very well known temperature measurement technique; several have been reported in the past.

This featured review article in Metrologia (Acoustic gas thermometry M R Moldover et al 2014 Metrologia 51 R1) by six authors from six different  NMIs around the world provides a modern update on the technology and its significance in helping determine values of physical reference temperatures points on the International Temperature Scale of 1990 (ITS-90).

Acoustic Gas Thermometry

Authors: M R Moldover1, R M Gavioso2, J B Mehl3, L Pitre4, M de Podesta5 and J T Zhang6

Review Article ABSTRACT

We review the principles, techniques and results from primary acoustic gas thermometry (AGT). Since the establishment of ITS-90, the International Temperature Scale of 1990, spherical and quasi-spherical cavity resonators have been used to realize primary AGT in the temperature range 7 K to 552 K. Throughout the sub-range 90 K < T < 384 K, at least two laboratories measured (T − T90). (Here T is the thermodynamic temperature and T90 is the temperature on ITS-90.) With a minor exception, the resulting values of (T − T90) are mutually consistent within 3 × 10−6 T. These consistent measurements were obtained using helium and argon as thermometric gases inside cavities that had radii ranging from 40 mm to 90 mm and that had walls made of copper or aluminium or stainless steel. The AGT values of (T − T90) fall on a smooth curve that is outside ±u(T90), the estimated uncertainty of T90. Thus, the AGT results imply that ITS-90 has errors that could be reduced in a future temperature scale. Recently developed techniques imply that low-uncertainty AGT can be realized at temperatures up to 1350 K or higher and also at temperatures in the liquid-helium range.

The complete article can be obtained online at: http://iopscience.iop.org/0026-1394/51/1/R1/article.

About Metrologia

It is the leading international journal in pure and applied metrology, published by IOP Publishing on behalf of Bureau International des Poids et Mesures (BIPM), the International Bureau of Weights and Measures. It is published by the Institute of Physics (IOP) in The United Kingdom.

Online at: http://iopscience.iop.org/0026-1394
—————————

1 Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD, USA
2 Thermodynamics Division, Istituto Nazionale di Ricerca Metrologica, 10135 Turin, Italy
3 36 Zunuqua Trail, PO Box 307, Orcas, WA 98280-0307, USA
4 Laboratoire Commun de Métrologie LNE-Cnam (LCM), 61 rue du Landy, 93210 La Plaine Saint-Denis, France
5 National Physical Laboratory, Teddington, Middlesex, TW11 0LW, UK
6 National Institute of Metrology, Beijing 100013, People’s Republic of China

Precision & Accuracy in Measuring Surface Temperatures

A subject rife with errors, no matter how you look at it.

There’s a classic pair of books on temperature measurement that are hopelessly out of print. We are fortunate to have both in our little library. They are:

1. “Temperature Measurement in Engineering“, Volume I, by H.D Baker, E.A. Ryder and N.H. Ryder, John Wiley & Sons, Inc. New York and Chapman & Hall, Limited, London (Copyright 1953) Library of Congress Catalog Card Number 53-11565, and

2. “Temperature Measurement in Engineering“, Volume II, by H.D Baker, E.A. Ryder and N.H. Ryder, John Wiley & Sons, Inc. New York and London (Copyright 1961) Library of Congress Catalog Card Number 53-11565. Continue reading

The EarthTemp Network

 

Online — EarthTemp is a network to stimulate new international collaboration in measuring and understanding the surface temperatures of Earth. This will involve experts specialising in different types of measurement of surface temperature, who do not usually meet.

Their motivation is the need for better understanding of in situ measurements and satellite observations to quantify surface temperature as it changes from day to day, month to month.

Knowing about surface temperature variations matters because these affect ecosystems and human life, and the interactions of the surface and the atmosphere. (for more details, see motivations and objectives and scientific context – http://www.geos.ed.ac.uk/research/earthtemp/objectives.html and http://www.geos.ed.ac.uk/research/earthtemp/context.html).

The network is organised around three themes over three years.

In the first year (2012), they focused on Taking the temperature of the Earth: Temperature Variability and Change across all Domains of Earth’s Surfacehttp://www.geos.ed.ac.uk/research/earthtemp/themes/1_in_situ_satellite.

This is an inclusive question, designed to bring together research communities and develop a full picture of common research needs and aspirations.

The second year (2013) discusses Characterising surface temperatures in data-sparse and extreme regions (with an Arctic focus – http://www.geos.ed.ac.uk/research/earthtemp/themes/2_data-sparse).

EarthTemp People

Management group

Chris Merchant (Principal Investigator)
Dr. Chris Merchant is Reader in Earth Observation in the School of GeoSciences (University of Edinburgh). His principal expertise is use of thermal and reflectance imagery from satellites for observing surface temperature for climate applications, with interests also in lakes, aerosols, clouds, air-­sea fluxes and the radiation budget.

John Remedios (Co-Principal Investigator)
Prof. John Remedios is Professor of Earth Observation Science (EOS) in the Space Research Centre (University of Leicester). His research interests include surface temperatures and atmospheric correction; climate trends; measurements, retrievals and exploitation of tropospheric pollution and stratospheric composition; and validation and calibration of satellite instrument data.

Nick Rayner (Co-Principal Investigator)
Dr. Nick Rayner is a scientist at the Hadley Center (Met Office) where she leads the analysis of marine climate observations. Her expertise includes sea surface temperature, marine air temperature and sea ice observations, and the the statistical reconstructions of historical climate data.

Stephan Matthiesen (Project manager)
Dr. Stephan Matthiesen is a physicist and works as project manager and researcher at the School of GeoSciences (University of Edinburgh). He is also a freelance translator and editor of scientific texts.

Steering group

Jacob L. Høyer, Danish Meteorological Institute (DMI)
Phil Jones, University of East Anglia (UEA)
Folke Olesen, Karslsruhe Institute of Technology (KIT)
Hervé Roquet, Centre de Météorologie Spatiale, MeteoFrance
José Sobrino, University of Valencia
Peter Thorne, National Oceanic and Atmospheric Administration (NOAA)

Website support: Science and Engineering at The University of Edinburgh

Website: http://earthtemp.org/

News Feed: http://www.google.com/reader/public/atom/user/15733979554046153349/state/com.google/broadcast