Type K Thermocouple [Full Guide] - Peak Sensors (2024)

What Is A Type K Thermocouple?

Type K Thermocouple is a Base metal thermocouple made from conductors containing Nickel – Chromium, and Nickel – Aluminium alloys and is suited for measuring temperatures up to +1200°C. We are K-type thermocouple manufacturers and can produce K-type thermocouple sensors based on your specifications or as replacements for existing sensors. We have manufactured thermocouples for over 25 years and are solely focused on designing and manufacturing temperature sensors. Please call or email us to discuss your requirements.

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How Do Type K Thermocouples Work?

Type K thermocouples operate based on the Seebeck effect, which generates a voltage when there is a temperature difference between the two junctions of dissimilar metals. This voltage is proportional to the temperature difference and can be measured to determine the temperature at the sensing junction accurately. The relationship between temperature and voltage is well-characterised and can be represented by specific calibration tables or equations.

K type thermocouples can come in a variety of designs suited to different applications. View the details of each type of design we offer for the type K thermocouples range.

  • Mineral Insulated Type K – Metal sheath insulated with magnesium oxide powder also called MIMS.
  • Cable/Wire Type K – Flexible sensors in PVC, PTFE or Glass Fibre. Many cold and hot-end designs.
  • Type K with Ceramic Sheaths – High-temperature design with ceramic protection sheath
  • Type K with Metal Sheaths – High temperature design with metal protection sheath
  • Type K Inserts – Rigid metal tubes commonly used in pocket, thermowell or head assemblies.
  • Type K Elements – Basic elements for further assembly into sheaths or equipment.

K Type Thermocouple Specifications

K type thermocouple sensors are by far the most common thermocouple type in use. It is quite an inexpensive sensor and we can manufacture many different designs of this thermocouple type. Its range is common for many industrial processes and is the main base metal thermocouple before switching to a rare metal thermocouple. The high nickel content of Type K means it is a very stable sensor. Thermocouple type K is unsuitable for reducing atmospheres unless it is protected by a sheath. It’s sensitivity is around 41 µV/°C.

Type K Thermocouple Temperature Range

Continuous:

0 to +1100 °C

Short Term:

-180 to +1300 °C

Type K Thermocouples Material

Chromel (90%Ni, 10%Cr)

Alumel (95%NI, 2%Mg, 2%Al, 1%Si)

Type K Thermocouple Tolerance Details

Tolerance Class 1

-40 to +375 ± 1.5 °C

375 to 1000 ± 0.004*[t]°C

Tolerance Class 2

-40 to +333 ± 2.5 °C

333 to 1200 ± 0.0075*[t]°C

Type K Thermocouple Colour Codes

IEC Colour Code

Type K Thermocouple [Full Guide] - Peak Sensors (1)

BS Colour Code

Type K Thermocouple [Full Guide] - Peak Sensors (2)

ANSI Colour Code

Type K Thermocouple [Full Guide] - Peak Sensors (3)

How To Test A Type K Thermocouple?

Testing a Type K thermocouple involves verifying its output voltage or temperature readings against a known reference source or calibrated instrument. This can be done using specialised thermocouple simulators, temperature baths, or other temperature measurement devices. Additionally, visual inspection for physical damage or signs of wear can also indicate the need for replacement or recalibration.

How To Calibrate A Type K Thermocouple?

Calibrating a Type K thermocouple involves comparing its output against known temperature standards over a range of temperatures. This process ensures that the thermocouple provides accurate temperature measurements within the specified tolerance limits. Calibration can be performed using certified temperature references and calibrated instruments following established procedures and standards.

How To Check A Type K Thermocouple With A Multimeter?

To check a Type K thermocouple with a multimeter, you can follow these steps:

  1. Set the multimeter to measure voltage (mV).
  2. Disconnect the Type K thermocouple from any circuitry.
  3. Connect the multimeter leads to the two ends of the Type K thermocouple.
  4. Read the voltage displayed on the multimeter.
  5. Compare the measured voltage with the expected voltage at a known temperature using Type K thermocouple reference tables or conversion formulas.

Which Wire Is Positive On A Type K Thermocouple?

In a Type K thermocouple, the positive wire is typically made of chromel (Nickel-Chromium), while the negative wire is made of alumel (Nickel-Aluminum).

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We’ve made Type K Thermocouples for over 25 years and today we are considered the best choice for custom built temperature sensors in the UK. We continue to apply our expertise and invest in the latest technology to provide our customers with the highest quality temperature sensors available.

Contact us with your requirements if you have an existing sensor design or are unsure what you need we’ll be able to find you get the right sensor for your process.

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Type K Thermocouple [Full Guide] - Peak Sensors (2024)

FAQs

What is the range of a Type K thermocouple sensor? ›

Type K thermocouples have a general temperature range of -200 to 1260°C (-326 to 2300°F), however there are some caveats to this: If used for temperatures below 0°C special material is needed in order to meet the specified accuracies. Also, Special Limits of Error are not specified for temperatures below 0°C.

What is the response of K-type thermocouple? ›

A 1/4-inch wide, sheathed, ungrounded type K thermocouple responds to temperature changes in water in about 2.25 seconds. A bare thermocouple wire responds in just over 0.6 seconds.

How accurate is the K-type thermocouple sensor? ›

The Negative leg is Alumel, Nickel-Aluminium (5% aluminum). The accuracy of a K-type Thermocouple is typically a maximum of +/- 2.2°C or +/- 0.75%, whichever is greater. However, there can be differences between different thermocouples, ven coming from the same production batch due to deviations in the alloys.

How do you calculate K-type thermocouple? ›

Type K Thermocouples - coefficients of approximate inverse functions giving temperature, t90, as a function of the thermoelectric voltage, E, in selected temperature and voltage ranges. The functions are of the form: t90 = co + c1E + c2E2 ciEi where E is in microvolts and t90 is in degrees Celsius.

What are the limitations of Type K thermocouples? ›

The Advantages and Disadvantages of Type K Thermocouples

However, they may have lower accuracy, limited high-temperature capability, and susceptibility to magnetic interference. Unsuitable for inert or reducing atmospheres, they also have limited corrosion resistance and a potential for oxidation.

How to check a type K thermocouple? ›

Testing a Type K thermocouple involves verifying its output voltage or temperature readings against a known reference source or calibrated instrument. This can be done using specialised thermocouple simulators, temperature baths, or other temperature measurement devices.

What is the output signal of a Type K thermocouple? ›

Why To prefer K Type Thermocouple. It has integrated composition of Chromel and Alumel wires has a range of -270 °C to 1260°C and an output of -6.4 to 9 mV over maximum temperature range.

Which wire is positive on a Type K thermocouple? ›

In ANSI color coding, the red wire of a thermocouple is negative, and the positive wire is color coded to the type of thermocouple. A type K thermocouple has one red wire and one yellow wire. Type K thermocouples have a useful temperature range of negative 200 to 1,250 degrees Celsius.

What is the error of Type K thermocouple? ›

The error for a standard grade K-type thermocouple is ±2.2 °C or ±0.75% of the measurement temperature. ‡ Because ±0.75% of 200 °C (±1.5 °C) is less than ±2.2 °C, the error of a standard grade K-type thermocouple is ±2.2 °C.

How far can you run Type K thermocouple wire? ›

Practically speaking, the longest you want to go with a standard thermocouple run is about 100 feet without having to start jumping through hoops to get an accurate, low-noise measurement. Even in this case, you will probably want to use shielded, SLE wire at least 18 gauge or larger.

How do you check thermocouple accuracy? ›

Disconnect it from the gas valve and connect a multimeter set to millivolts. Apply heat to the tip and check the reading. A properly functioning thermocouple will generate 15-35 millivolts when heated. If below 15 millivolts, the thermocouple must be replaced.

What is the most accurate thermocouple? ›

Accuracy: Type T thermocouples have the tightest accuracy of all the base metal thermocouples at ±1C or ±0.75% whichever is greater. This is followed by Type E (±1.7C or 0.5%) and Types J, K and N (±2.2C or 0.75%) for standard limits of error (per ANSI/ASTM E230).

What is the maximum temperature for a Type K thermocouple? ›

Due to its reliability and accuracy, Type K is used extensively at temperatures up to 1260°C (2300°F).

What is the tolerance of a Type K thermocouple? ›

Type K Accuracy (whichever is greater): Standard: +/- 2.2C or +/- . 75% Special Limits of Error: +/- 1.1C or 0.4%

What is the formula for thermocouple sensor? ›

The governing equation for this is: Eemf = −S∆T = S(THOT − TCOLD), where: Eemf is the voltage output of the thermocouple. S is a temperature-dependent material property, known as the Seebeck coefficient (For a type K thermocouple, this is roughly 4.1 μV/°C between 0°C and 1000°C)

What is the voltage range of K-type thermocouple? ›

The K-type thermocouple has a range of approximately −6.5mV to +55mV, if the temperature measurement range is from −270°C to 1370°C. This range is used to maximize the resolution of the measurement, considering the full-scale range of the ADC.

What is the range error of K-type thermocouple? ›

Type K Accuracy (whichever is greater): Standard: +/- 2.2C or +/- . 75% Special Limits of Error: +/- 1.1C or 0.4%

What is the operating range of thermocouple sensor? ›

What temperature range are thermocouples suitable for? This is very much dependent on type but the overall range for all thermocouple types is -200°C to +1800°C. There are many factors to consider when selecting a thermocouple type for an application and we would be happy to offer assistance where possible.

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