Thermocouples are ubiquitous. Whether you are 20 days or 20 years into the industry, you know the essential role they play in making sure heat treat processes are running efficiently, accurately, and dependably. This quick trivia questionnaire will test your thermocouple knowledge on a dozen either obscure or obvious facts about thermocouples.
Los termopares son ubicuos. Sin importar que tu experiencia en la industria sea de 20 días o 20 años, conoces bien el papel esencial que juegan en asegurar que los procesos de tratamiento térmico avancen de manera eficiente, precisa y confiable...
Take the English version of the quiz below, or find the Spanish translation when you click the flag above right!
If you have any facts of your own about thermocouples, our editors would be interested in sharing them online at www.heattreattoday.com. Email Bethany Leone at bethany@heattreattoday.com with your own trivia!
This Technical Tuesday article, first published in English and Spanish translations, is found in Heat Treat Today's November 2022 Vacuum print edition.
Thermocouple Trivia
1. What thermocouple type potentially has the longest life (but is also the most expensive)?
(a) Type K (Chromel-Alumel)
(b) Type N (Nicrosil-Nisil)
(c) Type R (Platinum-13% Rhodium)
(d) Type J (Iron-Constantan)
2. What is something you might find at home that uses a thermocouple to control its temperature?
(a) Your oven
(b) Your toaster
(c) Your water heater
(d) All of the above
3. What do you need to know when purchasing thermocouples for your heat treat furnace or oven?
(a) The length of the thermocouple
(b) The process application you are running
(c) The type of thermocouple best suited for the
(d) All of the above
4. Who was Thomas Johann Seebeck?
(a) The person credited with describing the scientific theory behind thermocouples
(b) An advocate for the elimination of thermocouples in furnaces and ovens
(c) A German physicist who was responsible for helping develop rockets for the United States
(d) None of the above
5. What would be the best thermocouple to use to control the temperature of an oil quench tank?
(a) Type R (platinum — 13% rhodium)
(b) Type S (platinum — 10% rhodium)
(c) Type K (chromel-alumel)
(d) Type J (iron-constantan)
6. Why use an over temperature (aka "excess temperature") device on your furnace or oven?
(a) For better process control, it is always helpful to have more than one thermocouple in the furnace/oven
(b) To prevent the furnace temperature from running away and damaging the equipment
(c) An obsolete device no longer required by NFPA 86
(d) A method of ensuring the process being run in the furnace stays close to the set point temperature
7. How are thermocouples used in the heat treat industry?
(a)temperature control devices
(b) As part of a safety system designed to prevent the furnace/oven from running away and damaging itself
(c) To ensure that temperature, the most important process parameter, is maintained within limits necessary to successfully run a heat treat process
(d) All of the above
8. Why use type K versus type N thermocouples?
(a) Because type K has better accuracy
(b) Because type K has better temperature limits
(c) Because type K is more expensive
(d) None of the above
9. Thermocouples produce what type of voltage?
(a) PPM (parts per million)
(b) EMF (electromotive force)
(c) EMP (electromagnetic pulse)
(d) mV (millivolt)
10. What are some of the most common reasons why a thermocouple “drifts” or fails in a heat treat furnace or oven?
(a) Age
(b) Running at temperatures higher than its rated use temperature
(c) The wrong thermocouple type is used
(d) All of the above
11. What is a common problem seen in thermocouples that fail in service?
(a) Green rot (oxidation of chromium)
(b) Metal dusting (aka "catastrophic carburization")
(c) Grain growth
(d) All of the above
12. Complete the sentence: Types S, R, and B noble metal thermocouples are generally specified for use . . .
(a) . . . when temperatures exceed the upper recommended operating temperatures of base metal thermocouples.
(b) . . . after failing compliance on three SATs .
(c) . . . if the furnace only processes automotive parts.
(d) . . . to safeguard against low temperature readings in large loads.
Trivia Key
Compare your answers with the key on page 26 . How did you stack up in thermocouple knowledge? See where your skills measure up in the scale below.
Learn more about thermocouples in the interview between Doug Glenn and Eric Yeager on page 16 or check out the reference list below.
References
Alexander, Colleen Stroud, et al. “Application of Ribbon Burners to the Flame Treatment of Polypropylene Films.” Platinum Thermocouple - an Overview | ScienceDirect Topics, 20 June 2008, https://www.sciencedirect.com/topics/engineering/platinum-thermocouple.
“Introduction to Thermocouples.” A Perfect Alliance Between Expertise and Know-How, RDC Control, 16 Dec. 2017, https://rdccontrol.com/thermocouples/thermocouples-101/introduction-to-thermocouples/.
Nash, William, and Eric Yeager. “Industrial Heating Magazine: How Long Should My Thermocouple Last?” Cleveland Electric Laboratories, 13 Sept. 2021, https://clevelandelectriclabs.com/industrial-heating-magazine-how-long-should-my-thermocouple-last/.
REOTemp Instruments. Thermocouple, 2011, https://www.thermocoupleinfo.com/.
Staff, Editorial. “Thermocouples Green Rot Effect.” Inst Tools, 20 Nov. 2019, https://instrumentationtools.com/thermocouples-green-rot-effect/.
“Thomas Johann Seebeck.” Editors of Encyclopaedia, Encyclopaedia Britannica, Encyclopaedia Britannica, Inc., 5 Apr. 2022, https://www.britannica.com/biography/Thomas-Johann-Seebeck.
“What Are Thermocouples Used for?” Enercorp Instruments What Are Thermocouples Used for Comments, 2020, https://enercorp.com/what-are-thermocouples-used-for/.
Heat Treat Today would also like to thank the following for their expert input: Dan Herring, The Heat Treat Doctor® at The HERRING GROUP, Inc.; Hank Prusinski, Summit Aerospace Products Corp.; and Andrew Bassett, Aerospace Testing and Pyrometry.
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