Type B | GUILCOR SENSORS

Type B
Temperature sensors

High-temperature thermocouple for extreme applications up to 1800 °C, ideal for furnaces, metallurgy, and laboratory environments.

Maximum precision
+/- 0,5°K

Minimum temperature
600°C

Maximum temperature
+1820°C

Minimum dimensions
1 x 1 x 1

Response time
Low

Internal Resistance
High

Linearity
High

Price
High

What is a Type B thermocouple ?

The type B thermocouple is a high-precision temperature sensor based on two alloys of platinum and rhodium.

It is specifically designed to measure extreme temperatures (up to +1,820 °C) while providing excellent long-term stability.

It is the preferred choice for laboratories, industrial furnaces, and glassworks.

Operating principle

The type B exploits the Seebeck effect: when there is a temperature difference between the hot junction and the cold junction, a voltage (in mV) is generated.

Simplified formul:

E = S × (T_hot - T_cold)

where S is the Seebeck coefficient, specific to each type of thermocouple.

For type B:

S ≈ 10 µV/°C around 1,000 °C

The voltage produced is proportional to the temperature difference between the two junctions.

Technical specifications

Parameter	Typical Value
Measurement range	+600 °C → +1 820 °C
Sensitivity	10 µV/°C to 1 000 °C
Tension at 1,000 °C	≈ 6,4 mV
Tension at 1,800 °C	≈ 13,8 mV
Materials	Pt-30Rh / Pt-6Rh
Oxidation resistance	Excellent
Response time (6 mm diameter sheath)	6 to 10 s
Reference standard	IEC 60584-1, ASTM E230

Voltage / Temperature Curve

The type B curve is almost linear at high temperatures, and the voltage remains nearly zero between 0 °C and 100 °C, making this thermocouple unsuitable for low temperatures.

Compatibility / Compensation

The type B thermocouple is used in 2 wires, connected to a measuring instrument via a compensation or extension cable suitable for type B.

Application areas

🧱 Industrial furnaces, metallurgy, ceramics, glass

🔬 Reference and calibration laboratories

⚙️ High-temperature process control

🧪 Research in materials and high-energy chemistry

Should I choose a Type B thermocouple ?

Strengths points

🔥 King of High Temperatures
→ The type B measures up to +1,820 °C continuously without degrading — it is the choice for furnaces, glassworks, and melting laboratories.
⚗️ Exceptional stability over time
→ Thanks to its platinum-based alloys, drift is almost nonexistent even after thousands of hours at high temperatures.
🧠 Reproducible precision
→ His performances are extremely consistent, making him a benchmark for industrial calibrations.

Weaknesses points

💸 High price
→ Platinum and rhodium are expensive: this sensor is reserved for critical applications, not for everyday use.
🌡️ Insensitive to low temperatures
→ Below 600 °C, the signal becomes too weak for a reliable measurement.
🐢 Slow response time
→ The refractory sheath necessary to withstand high temperatures slows down the thermal response.

Useful information

Here is some useful information regarding Type B thermocouples.

Temperature ↔ Voltage (mV vs °C)

(Reference: cold junction at 0 °C, IEC 60584-1 standard)

Temperature (°C)	Tension (mV)	Temperature (°C)	Tension (mV)
600	0,291	1 200	5,891
700	0,944	1 300	6,965
800	1,708	1 400	8,136
900	2,586	1 500	9,413
1 000	3,584	1 600	10,809
1 100	4,703	1 700	12,324
1 180	5,600	1 820	13,820

💡 Between 0 and 600 °C, the voltage remains almost zero (< 0.3 mV), which is why it is not used for low temperatures.

Accuracy classes (according to IEC 60584-1)

Class	Tolerance (°C)	Usage area	Description
Class 1	±(0.5% of the value)	600 → 1 700 °C	High precision
Class 2	±(0.5% or ±2.5 °C, the greater of the two)**	600 → 1 700 °C	Industrial standard
Class 3	–	Not applicable	The type B does not have a class 3 according to IEC

🔹 Even class 2 offers sufficient accuracy for the majority of industrial processes.

Application example – Voltage/Temperature calculation

🔸 Example 1 – Calculation of the generated voltage

If the measured temperature is 1,200 °C,

and the cold weld is at 0 °C, then :

E = 5,891 mV

If the cold weld is at 25 °C, we correct with the equivalent voltage (~0.018 mV), so:

E_corrected = 5.891 - 0.018 = 5.873 mV

✅ Actual tension to read ≈ 5.87 mV

🔸 Example 2 – Calculating temperature from a measured voltage

Measured voltage: 10.809 mV (cold weld at 0 °C)

→ By consulting the IEC table, this value corresponds to:

T=1600°C

✅ Measured temperature ≈ 1,600 °C

Integration diagram in an electronic system

The type B thermocouple produces a voltage of a few millivolts.

It therefore requires a precise differential amplifier, cold junction compensation, and a high-resolution analog-to-digital converter.

🔹 Typical components

Component	Function
Thermocouple type B (Pt30Rh / Pt6Rh)	Generate the Seebeck voltage
Differential amplifier (e.g., AD8495-B, INA333)	Amplify the signal µV → V
Compensation sensor (NTC or integrated sensor)	Measure the temperature of the cold weld
ADC 16–24 bits	Convert the amplified signal
Microcontroller / data acquisition system	Calculate the final temperature

🔹 Functional diagram (ASCII)

 [HOT JUNCTION]──(Thermocouple B)──[AMPLIFIER]──[ADC]──[µCONTROLLER]
                                      │
                                      └──(Compensation sensor)

💡 This setup ensures accurate measurement even at 1,800 °C, with an error of less than ±0.5 °C if properly calibrated.