Thermocouple FAQs:

Q: Is a thermocouple an electrical device consisting of two dissimilar electrical conductors forming electrical junctions at differing temperatures?

A: Yes.

Q: Is a thermocouple used in the closed loop control of a thermostat or other temperature controller?

A: Yes, and this can lead to a runaway overheating event and possibly severe damage, as the false temperature reading will typically be lower than the sensing junction temperature.

Q: Is a thermocouple converted from the heat which must be supplied to the hot side to maintain the electric potential?

A: Yes.

Q: Is a thermocouple proportional to the square of pressure over the low- to medium-vacuum range?

A: Yes.

Q: Are thermocouples used extensively in the steel and iron industries to monitor temperatures and chemistry throughout the steel making process?

A: Yes.

Q: Is a thermocouple pulled partly out of a furnace—as the sensor is pulled back?

A: Yes, and aged sections may see exposure to increased temperature gradients from hot to cold as the aged section now passes through the cooler refractory area, contributing significant error to the measurement.

Q: Was a thermocouple first used as a vacuum gauge by Voege in 1906?

A: Yes.

Q: Are thermocouples usually used only for high-temperature measurements due to their high cost and low sensitivity?

A: Yes.

Q: Are thermocouples a widely used type of temperature sensor?

A: Yes.

Q: Are thermocouples suited for use at up to 1800 °C?

A: Yes, Type-B thermocouples produce the same output at 0 °C and 42 °C, limiting their use below about 50 °C. The emf function has a minimum around 21 °C, meaning that cold-junction compensation is easily performed, since the compensation voltage is essentially a constant for a reference at typical room temperatures.

Q: Are thermocouples well suited for measuring extremely high temperatures?

A: Yes.

Q: Are thermocouples often used at high temperatures and in reactive furnace atmospheres?

A: Yes.

Q: Are thermocouples accuracy?

A: Yes, system errors of less than one degree Celsius can be difficult to achieve.

Q: Are thermocouples suited for measurements in the −200 to 350 °C range?

A: Yes.

Q: Are thermocouples suitable for use between −270 °C and +1300 °C?

A: Yes, and owing to its stability and oxidation resistance.

Q: Were thermocouples installed?

A: Yes.

Q: Are thermocouples regularly used in the electric arc furnace process to accurately measure the temperature of steel before tapping?

A: Yes.

Q: Are thermocouples widely used in science and industry?

A: Yes.

Q: Were thermocouples used as the practical standard thermometers for the range of 630 °C to 1064 °C?

A: Yes, and based on an interpolation between the freezing points of antimony, silver, and gold.

Q: Are thermocouples that junctions must be made cleanly without involving a third metal?

A: Yes, and to avoid unwanted added emfs.

Q: Is a thermocouple sometimes employed to ensure that the main burner ignites within a certain time period?

A: Yes, and shutting off the main burner gas supply valve should that not happen.

Q: Are thermocouples affected by issues such as alloy manufacturing uncertainties?

A: Yes, and aging effects, and circuit design mistakes/misunderstandings.

Q: Is a thermocouple placed in the pilot flame?

A: Yes, and generating a voltage which operates the supply valve which feeds gas to the pilot.

Q: Are thermocouples only partly modified?

A: Yes, for example being unaffected in the parts outside the furnace.

Q: Are thermocouples also used in homes?

A: Yes, and offices and businesses as the temperature sensors in thermostats, and also as flame sensors in safety devices for gas-powered major appliances.

Q: Are thermocouples suitable for measuring over a large temperature range, from −270 up to 3000 °C?

A: Yes, Applications include temperature measurement for kilns, gas turbine exhaust, diesel engines, other industrial processes and fog machines.

Q: Are thermocouples inexpensive?

A: Yes, and interchangeable, are supplied with standard connectors, and can measure a wide range of temperatures.

Q: Are thermocouples self powered and require no external form of excitation?

A: Yes.