NPL Video from fixed points to PRT & TC Traceability

Contact thermometry reference fixed points for ITS90 at NPL

A 33 minute science lecture describing a journey from the argon triple point to the iridium-carbon eutectic point in the context of UK industry needs

by Jonathan Pearce, NPL Temperature & Humidity group, Engineering Measurement Division

Contact thermometry is temperature measurement using sensors in contact with the medium to be measured. They are generally either resistance thermometers or thermocouples. Read more NPL Video from fixed points to PRT & TC Traceability

Resistance Thermometry (Continued) – Lecture 16

The Eighth Lecture in the 11 Lecture Sub-Series on Temperature Measurement.

Also online at and NPTEL at:

Lecturers for these videos are Prof. Shunmugam M. S., Department of Mechanical Engineering , IIT Madras.(email: and.Prof. S.P. Venkateshan, Department of Mechanical Engineering , IIT Madras (email:

Numbers after the lecture title indicate the length of the lecture in (hh:mm:ss) format. You can appreciate from the list and times shown, this is about a 50 hour course, equivalent to a substantial opportunity to learn the topics in significant depth.

Lectures in this course: 50

– Syllabus: PDF.

RTD Vendors

RTDs (Resistance Temperature Detectors)  are wire wound and thin film devices that depend on the temperature coefficient of electrical resistance of metals. As the temperature increases, the positive temperature coefficient of the metal produces an increasing resistance value.

You can read more about them and how they work on the companion RTD pages.

Some metals have a nearly ideal, linear coefficient, like platinum . While other materials have more non-linear coefficients, such a copper and nickel.

This page provides links to some of the vendors of these devices.

You may note some redundancy with links on related pages. A good part of that is due to the fact that some vendors supply more than one type of sensor, plus many provide technical, applications and related support to customers and prospective ones.

Reading vendors literature can be a great, but unstructured way, to gain some technical knowledge. The only danger is that it is hard to learn more than the vendor puts in their literature or what their salesperson knows.

That approach can be quite variable but certainly does not make it easy for you to evaluate products without benchmarks.

Some advice (non-definitive): check with more than one vendor and get some education about these sensors from other sources, too.

There are books and courses available. Check your local library’s technical section or a engineering or science library at a university or technical college or school or the ISA or someone on the ASTM E20 Committee on Temperature Measurement.

ASTM E20 has a special subcommittee devoted to just RTDs. You can find more about their RTD standards on the RTD Standards Page of this site.

Thanks for visiting.

General Resources for Vendors

Some RTD Vendor Web Sites:

  1. Advanced Sensing Products (USA)
    A secondary standard PRT and precision RTD probe manufacturer. They make own RTD elements to completely control product quality. Provide NIST traceable calibration services with temperature ranging from -189 to 850°C. Customers are in metrology, instrumentation, power industry, turbine manufacturers and the military.
  2. ARi Industries(UK) Ltd home page
  3. Biodata: New Products (UK)
  4. Burns Engineering, Inc. (USA) designs and manufactures temperature products, for all industries and processes, with standard, custom, and Hazardous Location approved models. ISO-9001 Registered. ISO-17025 Accredited.(RTDs, Thermocouples, Engineered Sensors, Transmitters, Thermowells and Accredited Calibration Service)
  5. Conax Buffalo Technologies(USA)
    A leading manufacturer of temperature sensors including thermocouples and RTDs In Buffalo (where else?) New York.
  6. Ephy-Mess GmbH (Germany)
    Sensorik für thermischen Motorschutz, für die Verkehrstechnik, für den Anlagenbau und für Laboranwendungen: Pt-100, Pt-500, Pt-100, Wickelkopffühler auf Pt-100, Ni- und Cu- Basis.
  7. HL-Planar Technik(USA)
    US Office in Scottsdale Arizona–A leading supplier of Nickel and Copper RTDs
  8. JMS Southeast, Inc.
    In Statesville, North Carolina, USA
  9. Jumo Process Control RTD Sensors and a lot more-home page
  10. La Termotecnica (Italy)(Italiana and English)LA TERMOTECNICA e’ una societa’ Italiana, fondata nel 1976 e’ una tra le prime aziende italiane a produrre e progettare con tecnologia propria sonde a termocoppia e termoresistenza.
    LA TERMOTECNICA, an Italian company set up in 1976, is one of the leading companies in Italy in the production and design of temperature sensors based on proprietary thermocouple and RTD technology.
  11. M & Ma Sensorstech (USA & CHINA)
    A cooperative venture with Anhui Tiankang Co. Ltd. a measuring instrument design and manufacturing company. Their primary product lines are Resistance Temperature Detectors, thermocouples, temperature transmitters, compensating cable and complete sensor assemblies. They specialize in OEM and private labeled equipment due to their low cost, ISO-9000 approved manufacturing capabilities.
  12. Precon, Inc. (USA)
    RTDs, NTC Thermistors and Humidity Sensors available in standards or custom probes. Precon also designs and builds controllers and can provide turnkey sensing and control solutions
  13. Pyro Electric Inc. (USA & INDIA)A ‘Design to Engineer’ manufacturer of Thermocouples, RTDs and their assemblies, plus Temperature and Pressure gages. They have a track record as suppliers to Oil Refineries, Petrochemical Plants and other process industries. They are ISO 9001:2000 certified along with ATEX 94/9/EC approved. Customers include Exxon Mobil, Petronas, Reliance, GAIL, L & T Ltd, and Samsung.
  14. RDF Corp.(USA)
    RDF in New Hampshire; well known for their unique flexible film sensors, too.
  15. The RTD & SPRT supplier listings on (USA)
    The Free & Self Service Directories of Temperature & Moisture Sensor Resources
  16. RTD Company, (USA)
    Cambridge, Minnesota
  17. SDI (USA)
    Sensing Devices Inc., in Lancaster PA
  18. Smith Systems Inc (USA)
    Brevard, North Carolina, Standard and Custom Sensors for Speed, Motion and Temperature – Cabling and Controls
  19. STOLAB (USA)
    Accurate Industrial Thermometers
  20. Temp-pro inc.(USA)
    From Northampton, Massachusetts, where custom is part of Customer.
  21. Tempsens Instruments India
    An ISO 9001/2000 certified manufacturer of all types of RTDs, Thermocouples,Thermowells, Calibration Baths and associated accessories such as Connection Heads, Compensating Cable and Ceramic Tubes. They offer High Accuracy RTDs for general and special purposes. They are available in Class A, B, ½ , 1/3 , 1/5 DIN, 1/10 DIN with various sheath material such as SS304, 316, 310, Hastalloy,  Monel etc.
  22. THERMOCOUPLES & RTD’s (Zambia)
    Yes, Zambia in Africa
  23. Thermo-Electra b.v.(Netherlands)
    “Your partner in temperature sensors”-Industrial thermocouples RTDs and Thermowells
  24. Thermo-Kinetics (Canada)
    Manufacturing help from knowledgeable folks headquartered in Mississauga ONT with regional offices throughout the Provinces. where service is foremost!
  25. Weed Instruments(USA)
    Corporate Home Page From Texas
  26. Xian Diamond (China)
    Supply RTDs and assemblies mostly to OEMs.