Radiation thermometry: The measurement problem

Classic article by G. D. (Gene) Nutter from a NASA ARCHIVE et.al.

ASTM STP895 Cover
ASTM STP895 Cover (Image credit ASTM International)

This online article is very similar and covers most of the same materials as  “Radiation Thermometry — The Measurement Problem” delivered at a symposium sponsored by ASTM Committee E-20 on Temperature Measurement in cooperation with the National Bureau of Standards, Gaithersburg, MD on May 8, 1984.

This was subsequently published as the first chapter in the volume “Applications of Radiation Thermometry”, ASTM SPECIAL TECHNICAL PUBLICATION 895, J.C. Richmond, National Bureau of Standards and D.P. DeWitt, editors.

 

Radiation Thermometry—The Measurement Problem
Symposium Paper

January 1985 — STP895  STP38703S
The basic measurement problems of radiation thermometry are discussed, with emphasis on the physical processes giving rise to the emissivity effects observed in real materials. Emissivity is shown to derive from bulk absorptivity properties of the material. Blackbody radiation is produced within an opaque isothermal material, with partial internal reflection occurring at the surface.

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Gene Nutter wrote this and many other  technical articles on the subject of radiation thermometry, including another classic , “A High Precision Automatic Optical Pyrometer in Temperatures ITS measurement and Control in Science and Industry, Vol. 4, 519-530, Instrument Society of America (1972).

Description: “An overview of the theory and techniques of radiometric thermometry is presented. The characteristics of thermal radiators (targets) are discussed along with surface roughness and oxidation effects, fresnel reflection and subsurface effects in dielectrics.

“The effects of the optical medium between the radiating target and the radiation thermometer are characterized including atmospheric effects, ambient temperature and dust environment effects and the influence of measurement windows.

“The optical and photodetection components of radiation thermometers are described and techniques for the correction of emissivity effects are addressed.”

NASA Info:Link to article: https://archive.org/details/NASA_NTRS_Archive_19880014512

Publication date 1988-03-01
Topics NASA Technical Reports Server (NTRS), INFRARED RADIOMETERS, RADIATION PYROMETERS, TEMPERATURE MEASUREMENT, THERMOMETERS, BLACK BODY RADIATION, RADIANCE, SPACE COMMERCIALIZATION, SURFACE ROUGHNESS, THERMAL EMISSION, Nutter, G. D.,
Collection NASA_NTRS_Archive; additional_collections
Language English
Identifier NASA_NTRS_Archive_19880014512
Identifier-ark ark:/13960/t9h46mr2v
Ocr ABBYY FineReader 11.0
Pages 61

Ed Note (from the book jacket of the 1988 book “Theory and Practice of Radiation Thermometry”,  Edited by D.P. Dewitt and Gene D. Nutter, John Wiley & Sons, Inc.): “Gene D. Nutter is (was)  a senior staff member of the Instrumentation Center, College of Engineering, University of Wisconsin-Madison. He received his MS in Physics from  University of Nebraska and had been earlier associated with the National Bureau of Standards and Atomics International.”

Chapter 5 in the above referenced text is linked below below. a classic book on the theory & practices of radiation thermometry published in 1998. It was recently found on Amazon.com and ebay.com at the following links:

https://www.amazon.com/dp/0471610186/ref=rdr_ext_tmb FOR ABOUT $349.

AND for between $353 and $453 on ebay at:  https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR0.TRC0.H0.Xtheory+%26+practice+of+radiation+thermometry.TRS0&_nkw=theory+%26+practice+of+radiation+thermometry&_sacat=0

 

Earth as a Greenhouse

If you have problems understanding the science side of the (so called*) debate on Global Warming, consider Earth as a greenhouse**.

Whoops! It actually is!

Earth's global energy budget (PDF)
References: Trenberth, K. E., J. T. Fasullo, and J. Kiehl, 2009: Earth’s global energy budget (PDF). Bull. Amer. Meteor. Soc., 90, No. 3, 311-324,

Gases in the atmosphere that trap heat in the atmosphere are called greenhouse gases.

The USA’s Environmental Protection has an interesting webpage at https://www.epa.gov/ghgemissions/overview-greenhouse-gases that details the types of gases and their relative impact on Global Warming.

The most common and pervasive of these is, of course, Carbon Dioxide, known by its chemical designation CO2 and or the variation on that that is used by non-science types, CO2.

View the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2015 (published 2017), developed by the U.S. Government to meet U.S. commitments under the United Nations Framework Convention on Climate Change (UNFCCC).

Visit the public comments page to learn more about comments EPA received on the public review draft of the 1990-2015 GHG Inventory report.

Prior year versions of the GHG Inventory are available on the U.S. Greenhouse Gas Inventory Archive page. https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2015

https://www.epa.gov/ghgemissions/global-greenhouse-gas-emissions-data

https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2015

But, possibly unknown to the Administrator of EPA, the USA’s Department of Energy (DOE) has been working in the same area but with the objective of not only understanding sources and sinks of greenhouse gases like Carbon Dioxide, but with and eye to doing something about reducing it.

Here’s are some key links and a chart from the DOE website, Let’s hope that they don’t get “modified” in the pursuit of “political nonscience” – if this link vanishes, you’ll know – but in the interest of transparency we have copied the image and published it here.

The largest contributor to these emissions is from electricity production (73 percent).(click to learn more about sources and sinks)

The diagram depicting the stationary anthropogenic CO2 emissions by major industry is (from a DOE web page https://www.netl.doe.gov/research/coal/carbon-storage/carbon-storage-faqs/what-are-the-primary-sources-of-co2).

WHAT ARE THE PRIMARY SOURCES OF CO2?

Diagram depicting the stationary anthropogenic CO2 emissions by major industry.
The largest contributor to these emissions is from electricity production (73 percent).
(click to enlarge)

 Myth: Carbon dioxide comes only from anthropogenic sources, especially from the burning of fossil fuels.
Reality: Carbon dioxide comes from both natural and anthropogenic sources; natural sources are predominant.

Are the additional emissions of anthropogenic CO2 to the atmosphere impacting the climate and environment?

To learn more, search the web! The search engine that doesn’t track you and use your preferences in their business is DuckDuckGo.com and their search results for a search on “greenhouse effect” is at: https://duckduckgo.com/?q=greenhouse+effect&t=hf&ia=web.

_______________

*In a real debate both sides are assumed to be sincere. Most of the Global Warming critics deny proven science and few, if any, can provide reproducible, alternate scientific basis for their arguments. They just argue, the last bastion of obstructionism.

Thus, the deniers “side” is widely suspected of being not only insincere, but also biased against the facts in order to avoid taking needed action and denying only out of some other agenda than saving mankind’s future.

Recently some politicians in the USA have grudgingly agreed that the Earth is warming but continue the denial of man’s influence and the need to reduce greenhouse gases. Thus inaction persists in the USA and other countries with deniers in power. 

However the rest of the civilized world has better science educated populous and elected representatives and they are making an effort to help slow the effects of greenhouse gases.

**https://en.wikipedia.org/wiki/Greenhouse_effect

Glossaries

There are many specialized glossaries that cover the terms describing the unique details about temperature and moisture sensors and their uses and this page represents an attempt to index most of them in one place.

CONTACT TEMPERATURE SENSORS:

Thermistors: https://www.temperatures.com/blog/2018/04/04/thermistor-gloss…-and-terminology/.

Thermocouples:

RTDS: 

 

NONCONTACT TEMPERATURE SENSORS:

Many online articles about radiation thermometry and its uses (infrared thermometers, radiation pyrometers) exist including technology articles, PowerPoint slide presentations and .pdf downloads, but they seem to be vanishing as more and more “big businesses” take over these specialized sensors.But few are aimed at being useful glossaries or definition of terms.

There are some exceptions and some well-crafted pieces that have been online for a while and can be found in semi-hidden corners of the Web.

Thermal Radiation Thermometers: temperature_measurement_radiation_thermometers

Thermal Imaging:  (Glossary of Basic Thermography Terms) http://www.ne-spintech.com/Glossary%20of%20Basic%20Thermography%20Terms.pdf .

Clearly this is a work in progress, and it may be expanded in time. Priority will be according to the response it garners.

 

Thermistor Glossary and Terminology

Thermistor Terminology

A glossary slightly modified from that given in a US government publication: MIL-PRF-23648D.
Note that the term being described is in bold typeface. (Note also, that this replaces a part of the information page here on thermistors – it has been slightly edited from the original)

A thermistor is a thermally sensitive resistor that exhibits a change in electrical resistance with a change in its temperature. The resistance is measured by passing a small, measured direct current (dc) through it and measuring the voltage drop produced.

The standard reference temperature is the thermistor body temperature at which nominal zero-power resistance is specified, usually 25 °C.

The zero-power resistance is the dc resistance value of a thermistor measured at a specified temperature with a power dissipation by the thermistor low enough that any further decrease in power will result in not more than 0.1 percent (or 1/10 of the specified measurement tolerance, whichever is smaller) change in resistance.

The resistance ratio characteristic identifies the ratio of the zero-power resistance of a thermistor measured at 25 °C to that resistance measured at 125 °C.

The zero-power temperature coefficient of resistance is the ratio at a specified temperature (T), of the rate of change of zero-power resistance with temperature to the zero-power resistance of the thermistor.

A NTC thermistor is one in which the zero-power resistance decreases with an increase in temperature.

A PTC thermistor is one in which the zero-power resistance increases with an increase in temperature.

The maximum operating temperature is the maximum body temperature at which the thermistor will operate for an extended period of time with acceptable stability of its characteristics. This temperature is the result of internal or external heating, or both, and should not exceed the maximum value specified.
.
The maximum power rating of a thermistor is the maximum power which a thermistor will dissipate for an extended period of time with acceptable stability of its characteristics.

The dissipation constant is the ratio, (in milliwatts per degree C) at a specified ambient temperature, of a change in power dissipation in a thermistor to the resultant body temperature change.

The thermal time constant of a thermistor is the time required for a thermistor to change 63.2 percent of the total difference between its initial and final body temperature when subjected to a step function

The resistance-temperature characteristic of a thermistor is the relationship between the zero-power resistance of a thermistor and its body temperature.

The temperature-wattage characteristic of a thermistor is the relationship at a specified ambient temperature between the thermistor temperature and the applied steady state wattage.

The current-time characteristic of a thermistor is the relationship at a specified ambient temperature between the current through a thermistor and time, upon application or interruption of voltage to it.

The stability of a thermistor is the ability of a thermistor to retain specified characteristics after being subjected to designated environmental or electrical test conditions.

Thermography Service Providers

Below is a list of some Thermal Imaging Services or Directories where more lists can be found. It is not complete, we know.

Sorry if you were left out. If you should be listed or know of others who should be listed or if you want to improve your organization’s listing, let us know, please.

Note that the training organizations are listed on a separate page. Some of them provide classified ads for used equipment as do some of the service providers below.

Also, some of the training companies do other things, like practice thermography and run information exchange/training meetings at nice places in the Fall and Winter, like Orlando, New Orleans and Las Vegas.

Tell your new product and application stories at The Temperature Directories website: www.tempsensor.net or feedback to us and we’ll consider adding it here with your byline!

 

  1. AITscan(USA)
    A unique inspection service that has developed a high-tech approach to aerial infrared thermographic scans for large, flat-roofed buildings as well as locating Stormwater pollution sources and more. A most visually and technically rewarding website.
  2. Allis Engineering San Juan Capistrano, CA
  3. Chemical & Infrared INSPECTIONS, LLC (USA)
    Professional Services Assisting Industrial, Commercial and Residential Customers locate potential problems through Infrared Thermography and Structural Drug Detection
  4. Colbert Infrared Services, Inc. (USA)
    All of their Infrared Thermographers have completed the ASNT (American society of Non-destructive Testing) requirements for certified Thermographers, are members of the Professional Thermographers Association, and have had extensive training as Certified Thermal Trend Professional Solution Providers. The latter is their own software that they developed, sell and support for data collection, and fault-finding.
  5. Emerson Process Management/CSI (USA)
    Reliability Based Maintenance: vibration, tribology, oil lab services, motor monitoring, ir thermography, laser alignment, dynamic balancing, and RBM Services.
  6. The Infrared Training Center
    Provides a directory of IR service provider organizations (and much more) on their web site.
  7. Infrared Inspection’s   Lists of Service Providers:
  8. InfraredPredictive Surveys, Inc. (USA)
    A Maryland Corporation is “The Total Inspection and Survey Service for Architects, Owners and Industry”, that performs infrared inspections of electrical systems, ovens, bearings, gears, condensers, heat exchangers, belt drives, chain drives, refractory insulation, valves, hydraulic systems, pumps, tanks and electrical equipment and more.
  9. Infrared Services, Inc.(USA)
    A Colorado Corporation that has been doing electrical, distribution, power system, uninterrupted power systems, mechanical systems, rotating equipment, roof moisture, energy audits, glycol snow melt systems, plumbing leak detection and other nondestructive surveys for over 9 years.
  10. IRInfo’s Thermal Imaging Service List for Canada
  11. IRInfo’s Thermal Imaging Service List for Israel
  12. IRInfo’s Thermal Imaging Service List for Mexico
  13. IRInfo’s Thermal Imaging Service List for Trinidad
  14. IRInfo’s Thermal Imaging Service List for The USA-by State
  15. Jersey Infrared Consultants(USA)
    Focused on process and predictive maintenance, JerseyIR is known throughout the USA for its expertise in petroleum thermal cracking and petrochemical thermal reformer furnaces-Headquartered in Burlington New Jersey, near Philadelphia PA.
  16. Kleinfeld Technical Services, Inc. . Bronx, New York (USA).
    A unique company with IR Thermography, heat transfer analysis, process engineering and FEA consulting services run by Jack Kleinfeld, P.E., a graduate chemical engineer.
  17. Maintenance Reliability Group, Another unique organization, one aimed at the big picture of reliability in maintenance operations-with a strong thermography component. Run by Rich Wurzbach in south central Pennsylvania.
  18. PIRS – Pregowski Infrared Services (Poland)
    Twój przewodnik do sukcesu w zastosowaniu detekcji w podczerwieni (Your guide to success in application of infrared detection).
  19. Si Termografia Infraroja . Bueneos Aires, (Argentina),
    Services, consulting and products for infrared thermal imaging from Sr. Andrés E. Rozlosnik.
  20. Sierra Pacific Innovations(USA)
    SPI infrared thermography services thermal imaging infrared inspections. They have, according to their web site, the largest selection on the internet of new, demo, and previously owned imagers. 251 Waterton Lakes Avenue, Las Vegas, NV 89148.
  21. Stockton Infrared Thermographic Services, Inc.(USA)
    A major service company located in North Carolina. Stockton is dedicated to providing a wide range of quality infrared thermographic services to their clients. They do not manufacture or represent products of any kind and do not provide any services other than infrared. Their site features images, videos and a great deal of information on applications. Stockton is divided into four seperate divisions and provide the following services:
  • The Aerial Infrared Thermography at Stockton is performed by its AITscan Division: Stormwater and other unplanned and illicit water discharges into Waterways and Lakes can be found more quickly at much lower cost than shoeleather surveys with AITscan’s PollutionFindIR™ Services
  • Aerial Roof Moisture Surveying with RoofMoistureFindIR™ Services
  • Steam System Surveying with SteamLeakFinderIR™
  • Hot Water System Surveying with HotwaterLeakFinderIR™
  • Environmental Impact and Animal Counts with *AnimalFindIR Services
  • ELECTRICAL/MECHANICAL PREDICTIVE MAINTENANCE DIVISION * Electrical Switchgear IR/PM * Mechanical Systems IR/PM * Steam System Infrared *
  • BUILDING QUALITY ASSURANCE DIVISION * Building Structural Integrity * Heat Loss Analysis *
  • PROCESS IMPROVEMENT/R&D DIVISION * Process Improvement * On-line feasibility studies * Unbiased IR camera selection consulting * Pulp & Paper Industry Infrared * Infrared Research & Development
  • Snell Infrared(USA & Canada)
    A major thermal imaging service and training company
  • Snell Infrared’s List of Service Providers
  • Thermal Inspection Services,Allentown, PA(USA)
    Electrical, Mechanical, Roofing, Building Energy Audits, Production Process Evaluations
  • Therma Scan,(USA)
    An experienced industrial team of thermographers from the Northern Penninsula of Michigan (The U. P.)serving industry and commerce.
  • Thermal Vision (Ireland)
    State of art thermography service based near Dublin. Providing quality thermal imaging solutions worldwide.

About The Global Climate Observing System (GCOS) & More!

GCOS-aboutOnline — GCOS, the Global Climate Observing System, is a joint undertaking of:

  • The World Meteorological Organization (WMO),
  • The Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational Scientific and Cultural Organization (UNESCO),
  • The United Nations Environment Programme (UNEP) and
  • The International Council for Science (ICSU).

 

Its goal is to provide comprehensive information on the total climate system, involving a multidisciplinary range of physical, chemical and biological properties, and atmospheric, oceanic, hydrological, cryospheric and terrestrial processes.

It is built on the WMO Integrated Global Observing System (WIGOS), the IOC-WMO-UNEP-ICSU Global Ocean Observing System (GOOS), the UN Food and Agriculture Organization (FAO)-UNEP-UNESCO-ICSU Global Terrestrial Observing System (GTOS) and a number of other domain-based and cross-domain research and operational observing systems.

It includes both in situ and remote sensing components, with its space based components coordinated by the Committee on Earth Observation Satellites (CEOS) and the Coordination Group for Meteorological Satellites (CGMS).

GCOS is intended to meet the full range of national and international requirements for climate and climate-related observations.

As a system of climate-relevant observing systems, it constitutes, in aggregate, the climate observing component of the Global Earth Observation System of Systems (GEOSS)

The Global Observing System is an extremely complex undertaking, and perhaps one of the most ambitious and successful instances of international collaboration of the last 100 years. It consists of a multitude of individual observing systems owned and operated by a plethora of national and international agencies with different funding lines, allegiances, overall priorities and management processes.

Learn more at: https://library.wmo.int/opac/doc_num.php?explnum_id=3417 ,  http://www.wmo.int/pages/prog/gcos/index.php?name=AboutGCOS  and https://public.wmo.int/en/programmes.

 

Understanding Radiation Thermometry Parts I & II

From NASA Technical Reports Server (NTRS)

From NASA Article
From NASA Article

In 2015, Timothy K. Risch of NASA developed two technical articles that are available on the NASA Technical Reports Server (NTRS).

Both articles may be freely downloaded from NTRS in various formats, as long as the NASA Server maintains their presence.

As far as we know these are royalty free and the only stipulation that NASA usually requires is an attribution. These are below in the form of links to the article on the NASA web site.

The articles are entitled:

Understanding Radiation Thermometry. Part I, 71 pages, publication date 2015-07-08, and Understanding Radiation Thermometry. Part II, 111 pages, same publication date.

We have reviewed these documents and find them to be an excellent summary of this temperature measurement method and have archived them on our site in two formats, mobi, suitable for reading on an E-reader and in Adobe pdf format.

Part 1 provides and Overview, Nomenclature, a bit about what temperature is and the history of measurement methods and delves into the physics underlying Radiation Thermometry.

Part II covers practical radiation thermometers, some detail on measurement techniques and calibration and a brief reference list.

These files are linked below many be freely downloaded as long as we maintain this website.

The NASA description for both article reads as follows:

This document is a two-part course on the theory and practice of radiation thermometry.

Radiation thermometry is the technique for determining the temperature of a surface or a volume by measuring the electromagnetic radiation it emits.

This course covers the theory and practice of radiative thermometry and emphasizes the modern application of the field using commercially available electronic detectors and optical components.

The course covers the historical development of the field, the fundamental physics of radiative surfaces, along with modern measurement methods and equipment.
NASA Technical Reports Server (NTRS) 20150021314 Understanding Radiation Thermometry. Part I NASA Technical Reports Server (NTRS) Free Download & Streaming Internet Archive

Understanding Radiation Thermometry – Part I pdf Format Timothy K. Risch NASA Armstrong Flight Research Center July 8, 2015

NASA Technical Reports Server (NTRS) 20150021315 Understanding Radiation Thermometry. Part II NASA Technical Reports Server (NTRS) Free Download & Streaming Internet Archive

Understanding Radiation Thermometry – Part II pdf Format Timothy K. Risch NASA Armstrong Flight Research Center July 8, 2015

Sources on the NASA Technical Reports Server:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150021314.pdf

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150021315.pdf

The Use of Johnson’s Criteria for Thermal Infrared Camera & Systems Performance

Written by: Opgal staff writers  (August 03, 2017)

OPGAL Blog LinkOnline —  When customers are considering which thermal security camera or system to buy, one of the first questions asked of thermal imager manufacturers is usually: “At what distance can the IR camera detect a target?.

In other words, what is the camera’s ability to capture very small details at great distances?

When thinking about effective surveillance, it is indeed a good criterion to differentiate one sensor from another.

No matter which manufacturer you are buying from, the answer given to this question will almost always include the DRI ranges expression.

DRI refers to the distance at which a target can be Detected, Recognized, or Identified, based on certain universally accepted parameters.

In order to select the right sensor for your defense, security, or surveillance needs, these DRI ranges have to be, first, perfectly defined, but also assessed with regards to globally adopted industrial standards.

Enter: The Origin of Johnson’s Criteria

In 1958, at the first ever “Night Vision Image Intensifier Symposium”, John Johnson, a night vision scientist at the U.S. Army’s “Night Vision and Electronic Sensors Directorate” (NVESD), presented a paper named the Analysis of Image Forming Systems”.

Johnson’s paper defined a clear system with criteria and methodology for predicting an observer’s ability to find and assess targets using image intensifying equipment (such as thermal cameras), under various conditions. It worked well, and it was the first of its kind.

Johnson’s Criteria Definitions

Johnson’s model provided definitive criteria for calculating the maximum range at which “Detection, Recognition, and Identification (D, R, I)” could take place, with a 50% probability of success. (Orientation was also discussed, but this parameter is not used or recognized today).

Although newer methodologies for D,R,I exist today, such as NVESD’s “Night Vision Image Performance Model” (NV-IPM), the “Johnson’s Criteria” system was groundbreaking for its time, was the accepted standard in the defense industry for many years, and is still widely used in the security industry today.

Detection

Johnson defined “Detection” as the ability to subtend 1 TV line pair (+/- 0.25 line pairs) across the critical dimension of the subject (this translates to 2 pixels when using an LCD monitor). At the range that this occurs, regardless of target type, the observer could detect that a subject was in the field of view, 50% of the time. Today, many security camera companies loosely follow Johnson’s Criteria and define their camera’s “Detection” performance range as the ability to subtend either 1.5 or 2 pixels on the target, using various target sizes.

Recognition

Johnson defined “Recognition” as the ability to subtend 4 TV line pairs (+/- 0.8 line pairs) across the critical dimension of the subject (this translates to 8 +/- 1 pixels when using an LCD monitor). At the range that this occurs, regardless of target type, the observer determines the type of subject, a human or a car for example, 50% of the time. Today many security camera companies typically define their cameras “Recognition” performance range as the ability to subtend 6 pixels on the target, using various target sizes.

Identification

Johnson defined “Identification” as the ability to subtend 6.4 TV line pairs (+/- 1.5 line pairs) across the critical dimension of the subject (this translates to 12 +/- 3 pixels when using an LCD monitor). At the range that this occurs, regardless of target type, the observer could detect the subject.

Today many security camera companies loosely follow Johnson’s Criteria and define their cameras “Identification” performance range as the ability to subtend 12 pixels on the target, using various target sizes.

Long range performance

Johnson’s Criteria in the Security Industry

DRI ranges, expressed in kilometers (or miles), can usually be found in the specification table of infrared camera brochures, or in a description of the cameras features. While a very helpful jumping off point for narrowing down the options and homing in on the best systems, customers would be doing themselves a disservice to only look at DRI.

This is because today the application of Johnson’s criteria varies somewhat across the security industry. In most instances, documentation uses simplified or modified versions of the criteria, but they do all generally follow similar rules.

Typically, most companies use twelve pixels on the target for identification, six for recognition, and two for detection (sometimes 1.5). However, the target size can vary greatly. Normally the defense industry “NATO” target size (2.3×2.3 meters) is used for calculating the performance range for detecting vehicles, but for a human target, various target sizes can be found.

It is important when selecting your thermal infrared camera to keep in mind that in any given document, the target size for a human can range from 1.7-1.83 meters tall and from 0.3- 0.75 meters wide, and factor this into your decision-making process.

The Need to look at the Bigger Picture

Because end-users often place a high value on the written specifications of the camera, marketing departments are under pressure to use performance calculations that make their cameras look better than the competitors. However, since these calculations typically do not take environmental factors into account, customers should ask their thermal camera providers to explain the other elements and benefits of each camera they are offering, and how they will perform in a variety of conditions.

A modified approach that considers parameters such as these can better help in choosing the right or system for your needs.

The post appeared first on OPGAL.com.

Using Thermal Infrared in “Furnace and Heater Tube Inspections”

by Ron Lucier, ASNT NDT Level III

(From the IRInformIR.blogspot.com, September 27, 2017 with format altered for easier reading online – all text and images from IRInformIR)

ITC logo registered“One of the more challenging applications of infrared thermography is in the measurement of process heater and furnace tubes. In fact we get dozens of inquiries each year from our clients on this very subject.

“Since this is a very complex subject it is probably appropriate to start from the beginning.”

“Process Heaters”
There are as many uses for process heaters as there are designs. The basic configuration consists of a shell (outer casing), tubes (where the process fluid flows) and a heat source.

“These units are both thermodynamically and hydraulically complex.”

Process heater or furnace diagram

“In the simple drawing above we illustrate convective gas flow, which is turbulent, and radiant heat from the flame, refractory and other tubes – all non-uniform and time varying. When you view tube from an access port typically you can only see a portion of the tube or the tube at an oblique angle.

“Therefore, the odds are stacked against you from the start!”

“Why are heater tubes of interest anyway?”
Heater tubes 1“There are several reasons for inspecting tubes. Qualitatively slag (scale) buildup on the outside of the tube can be readily identified.

“Buildup on the inside of the tube (coking) is a bit more difficult but commonly performed.

“In both cases the slag or coke prevents the transfer of heat into the process fluid. In the case of slag buildup, the process fluid may not be sufficiently heated, affecting downstream processing.

“The case of coking on the inside of the tube is more serious. Since the coke has an increased resistance to heat transfer, the tube surface temperature increases.

“After all it is the flow of the process fluid that is keeping the tube “cool” in the first place.

“In fossil boilers this is called “DNB” – Departure from Nucleate Boiling and is usually caused by flame impingement, which initiates a layer of steam on the inside of the tube. The external tube surface, unable to conduct its heat to the water, increases dramatically, causing a failure (opening) in the tube.”

Read more »

ED NOTE: The SPIE has published a very useful and detailed book in its Tutorial Text Series entitled
Radiation Thermometry: Fundamentals and Applications in the Petrochemical Industry
Author(s): Peter Saunders (August 2007) that deals with this topic in depth from the point of view of non-contact temperature measurement (radiation thermometry). It contains a wealth of detail about the issues of slag and reflected thermal radiation as well as a useful tutorial on infrared temperature measurement.

It is available online at the SPIE bookstore at a modest price as both a softcover book and a pdf download.

The link is: https://spie.org/Publications/Book/741687.

Here’s some details from the (above) linked SPIE web page:

Book Description

This tutorial text provides an introduction to the subject of radiation thermometry, focusing on sources of measurement error and giving advice on methods for minimizing or eliminating these errors. Topics covered include: blackbody radiation, emissivity, reflection errors, and atmospheric absorption and emission; commonly used radiation thermometer types; uncertainty calculation; and procedures for in-house calibration of radiation thermometers. Included is a chapter containing detailed measurement examples for a variety of furnace types and operating conditions found in the methanol, ammonia, and refining industries.

Book Details
Date Published: 3 August 2007
Pages: 176
ISBN: 9780819467836
Volume: TT78

Industrial temperature measurement | Basics and practice

Free Download From ABB

(Extract From the Introduction)

With this Handbook for industrial temperature measurements we are attempting to provide the technician with solutions to his wide variety of responsibilities. At the same time, it provides for those new to the field, insight into the basics of the most important measurement principles and their application limits in a clear and descriptive manner.

The basic themes include material science and measurement technology, applications, signal processing and fieldbus communication.

A practice oriented selection of appropriate temperature sensor designs for the process field is presented as well as therequired communication capability of the meter locations.

The factory at Alzenau, Germany, a part of ABB, is the Global Center of Competencefor Temperature, with numerous local experts on hand in the most important industrialsectors, is responsible for activities worldwide in this sector.

125 years of temperature measurement technology equates to experience and competence. At the same time, it forms an important basis for continued innovation.

In close cooperation with our customers and users, our application engineers create conceptsto meet the measurement requirements.

Our Sector-Teams support the customer, planner and user in the preparation of professional solutions.

Free download available online at: https://library.e.abb.com/public/6bfb8fc893ac4d0da0a806ce8cd73996/03_TEMP_EN_E.pdf

Author Team:
Karl Ehinger, Dieter Flach, Lothar Gellrich, Eberhard Horlebein, Dr. Ralf Huck, Henning Ilgner, Thomas Kayser, Harald Müller, Helga Schädlich, Andreas Schüssler, Ulrich Staab,

ABB Automation Products GmbH

Many thanks to the publishing group at ControlEngineering-Europe for alerting us to this new online resource (http://www.controlengeurope.com/article/140944/Handbook-aims-to-simplify-industrial-temperature-measurement.aspx)