Thermocouple probe thermometers operate based on the principle of Seebeck effectThis principle states that the temperature difference between two points of contact of different metals will create an electrical potential difference (voltage). 

Thanks to this principle, thermocouples can measure a very wide temperature range, from -200°C to over 1700°C depending on the type of material used.

Detailed operating principle

1. Structure: A thermocouple consists of two conductors made of two different metals (e.g., chromium and alumine for type K) joined together at one end.
   • Hot joint (Junction): These are the ends welded together and in direct contact with the environment whose temperature needs to be measured.
   • Cold Junction (Reference Junction/Cold Junction): These are the two remaining wires, connected to the measuring device (e.g., voltmeter or temperature controller).
2. Seebeck effect: When there is a temperature difference between the hot and cold junctions, a small current will flow through the closed circuit, creating a current. thermoelectric electromotive force (Voltage in mV). This voltage value is directly proportional to the temperature difference between the two junctions.
3. Measurement and Transformation:
   • The measuring device (voltmeter) will measure the voltage value (mV) generated at the cold junction.
   • To determine the precise temperature at the hot junction, the temperature at the cold junction must be known or compensated (cold junction temperature compensation – CJC).
   • The measured voltage value is then converted into a temperature value (usually using a reference table or integrated processing circuit) and displayed on the screen.

Anritsu Meter Handheld Thermometer Model HR series

Thermocouple probe thermometers are classified primarily based on the type of metal material used to form the two conductors. These types are internationally standardized (according to IEC 60584 or ANSI MC96.1) and are designated by letters (J, K, T, E, N, R, S, B).

ANRITSU MW-32K-TC1-ASP copper wire temperature probe (-50 to 250°C)
This classification determines the appropriate temperature measurement range, accuracy, sensitivity, and operating environment for each type.

ANRITSU A-231K-01-0-TC1- ANP surface temperature probe type K -50°C ~ 500°C

Choosing a thermometer with a thermocouple probe requires careful consideration of technical factors to ensure the device operates accurately and reliably in your application environment.

1. Determine the temperature range to be measured. 

This is the most important criterion. Each type of thermocouple has a different measuring range: 

• Low to moderate temperatures (-200°C to 500°C): Types T, E, and J are usually good choices.
• Common industrial temperatures (0°C to 1200°C): Type K (most common) or N is the standard choice.
• Extremely high temperatures (above 1300°C): Precious metals such as R, S, or B are needed. 

Select the type of temperature sensor (K, T, E, etc.) and choose the connection type (ANP, ASP).

2. Consider the Operating Environment 

The environment surrounding the probe will affect the shielding material and the type of thermocouple: 

• A dry, clean, non-corrosive environment: Either an unshielded probe or a standard stainless steel-shielded probe can be used.
• Wet or chemically corrosive environments: A casing made of stainless steel (e.g., SUS316) or other specialized materials (such as Teflon) is needed to protect the metal wires inside.
• Environments with strong vibrations or high pressure: It is necessary to choose a probe with a robust construction, possibly a mineral-insulated (MI) type that can be flexibly bent. 

TOA Electric MF-SP-K Waterproof mold surface temperature sensor (type K/-200~ +200°C)

3. Requirements for Accuracy and Response Time 

• High precision: Type E is generally the most sensitive. Type T is accurate at low temperatures.
• Fast response time: The smaller the probe size (diameter), the faster the response time. The type of junction also affects this:
  • Exposed Junction: Very fast but easily corroded.
  • Grounded Junction: Moderately fast, striking a balance between speed and protection.
  • Ungrounded Junction: Slowest, but provides good protection against electrical interference and corrosion. 

4. Select the Thermometer Type (Display/Control Device) 

After selecting the appropriate probe, you need to choose a compatible display device: 

• Compatibility: Ensure the thermometer can correctly read the signal from the type of probe you choose (for example, a thermometer that only supports type K will not accurately read a type J probe).
• Additional features: Do you need features such as alerting, PID control, data logging, or computer connectivity? 

A&D AD-5601A type K thermocouple electronic thermometer (-50℃～＋1300℃)

A&D Thermocouple thermometer AD-5601A with Thermocouple Sensor AD-1217 (-50 to 500℃/ Φ15×L120mm) 

Thermometer with thermocouple probe 

Anritsu's HR series stands out thanks to its combination of High precision, Japanese-standard durability, and versatility. in many different industrial applications. 

ANRITSU digital Thermometer HR-1250K (-200 to 1370°C / Input connector ANP/ Type K)

Semiki We are a professional company in Vietnam providing both consulting services and distribution of temperature measurement solutions, including handheld thermometers and thermocouple probes from brands such as Anritsu, A&D, and TOA Electric…

Semiki not only sells products but also supports customers in choosing the most optimal solution. Semiki's team of engineers will help you:

Select your display/control device: We recommend Anritsu HR series thermometers or industrial temperature controllers that best suit your needs.

Determine the appropriate type of thermocouple: Based on the temperature range, measurement environment (corrosive, high pressure, vibration), and accuracy requirements, Semiki will advise on whether to use K, J, T, E, or precious metals (R, S, B).

Choose the optimal probe: Consultation on casing material (stainless steel 304, 316, Teflon), diameter, length, and joint type (insulated, exposed, open) to ensure durability and the fastest temperature response time.

As the official distributor of Anritsu Meter in Vietnam, Semiki is committed to providing genuine, brand-new 100% products with complete certification documents (CO/CQ), including:

• Anritsu handheld thermometer: We offer popular models such as HR-1150K, HR-1200E, HR-1300K/E, etc.
• Thermocouple probes come in a variety of types: We offer a range of probes for surface, liquid, air, and special applications, available in stock or by order.
• Accessories included: We provide connecting cables, software, batteries, and other warranty accessories.

You can contact Semiki directly using the information provided above to receive the best support for your temperature measurement needs.

Contact Semiki directly: You can find Semiki's contact information (via website or phone number) to request a quote and specific advice.

• Business email: [email protected]
• Phone number (Hotline): +84 979 761 016.
• Website: You can find out more details and send a consultation request via Semiki.com.