Detailed description of thermocouple products
A Thermocouple is a temperature sensor based on the Seebeck Effect, which measures temperature by generating a thermoelectric potential through a circuit composed of two different metal conductors. Due to its advantages such as wide temperature range, rapid response, high reliability and low cost, it is widely used in industries, scientific research, energy, medical care and other fields.
Thermocouple product classification
(1) Classify by graduation number (type)
Thermocouples with different material combinations are suitable for different temperature ranges and environments:
Type material (positive electrode/negative electrode) Temperature range (℃) characteristics Typical applications
K-type nickel-chromium (Cr)/nickel-silicon (Si) -200 to +1250, high cost performance, anti-oxidation industrial furnace, food processing
J-type iron (Fe)/copper-nickel (Cu-Ni) -40 to +750, high sensitivity, prone to oxidation, plastic injection molding, heat treatment
T-type copper (Cu)/copper-nickel (Cu-Ni) has good low-temperature stability ranging from -200 to +350, suitable for freezing and laboratory use
E-type nickel-chromium (Cr)/copper-nickel (Cu-Ni) -200 to +900 high output signal, chemical industry, aviation
N-type nickel-chromium-silicon (Cr-Si)/nickel-silicon (Si) -200 ~ +1300 high-temperature oxidation resistant industrial furnace
S-type platinum-rhodium 10 (PT-RH)/platinum (Pt) 0 ~ 1600 ultra-high precision, high-temperature resistant laboratory, metallurgy
R-type platinum-rhodium 13 (PT-RH)/platinum (Pt) 0 ~ 1600 is similar to S-type, with higher stability in scientific research and semiconductors
Type B platinum-rhodium 30 (Pt-Rh)/platinum-rhodium 6 (Pt-Rh) +200 ~ 1800 ultra-high temperature measurement glass furnaces, aerospace
(2) Classification by structure
Type characteristics and applicable scenarios
The bare wire thermocouple has no protective sleeve and responds extremely fast for laboratory and short-term measurements
Armored thermocouple metal sheath (stainless steel, Inconel), resistant to pressure and corrosion in industrial high-temperature and high-pressure environments
Standardized plugs for thermocouples with connection heads (such as Miniature, M12), equipment integration and automatic control
Surface thermocouples are flat or spring contact type for temperature measurement of pipe and mechanical surfaces
Thin-film thermocouples are ultra-thin (micrometer level), providing rapid response to electronic components and scientific research
2. Product technical parameters
Description of typical parameter values
The temperature measurement range of -200℃ to +1800℃ depends on the graduation number
The accuracy is ±1℃ to ±2.5℃ (standard grade), and the S/B type can reach ±0.1%
The response time is 0.1s to 10s. The armored type is slower, while the film type is the fastest
The output signal is at the microvolt level (μV/℃) for the K-type, approximately 41μV/℃
Insulation resistance >100MΩ (500VDC), leak-proof and anti-interference
Protection grade: IP65/IP67 (armored type), waterproof and dustproof
The maximum pressure resistance capacity is 100MPa (special armor), suitable for petroleum and deep well applications
3. Product Selection Guide
(1) Select the type of thermocouple
High temperature (>1000℃) : S-type, R-type, B-type
Medium temperature (-200℃ to 1000℃) : K type, N type, E type
Low temperature (-200℃ to 0℃) : T-type
(2) Select the material of the protective sleeve
The material is heat-resistant and suitable for various environments
304 stainless steel -200 ~ 800℃, general industrial
316 stainless steel corrosion-resistant at -200 to 900℃ (Chemical industry)
Inconel has high-temperature oxidation resistance ranging from 600 to 200 to 1150℃
Ceramic tubes at ultra-high temperatures of 1000-1800℃ (metallurgy)
(3) Select the installation method
Threaded installation (M6/M8/M12) - Pipes, reactors
Flange installation (DN25/DN50) - Boilers, large equipment
Clamp/Magnetic attraction - Temporary measurement
4. Typical application scenarios
✅ Industrial manufacturing: furnaces, heat treatment, injection molding machines
✅ Energy and power: boilers, gas turbines, nuclear power
✅ Laboratory: Materials research, ultra-low temperature experiments
✅ Medical: sterilization equipment, temperature monitoring
✅ Appliances: oven, water heater, coffee machine
5. Precautions
⚠ Cold end compensation: It needs to be combined with compensating wires or electronic compensation (such as MAX6675 chip)
⚠ Signal interference: It is recommended to use shielded wires to avoid strong electromagnetic fields
⚠ Regular calibration: Long-term high-temperature use may cause drift
