As a temperature sensor, thermocouple is usually used with display instruments, recording instruments and signal conditioners. Sheath thermocouple also can be used as a temperature sensing element for assembly thermocouple.
Specification:
1. S/E/K/J/T type thermocouple temperature range and accuracy chart
Category | Type of sensing element | Sheath diameter | Normal working temperature | Highest working temperature | Allowable deviation Δt |
Measuring range | Permissible deviation |
Platinum Rhodium 10 - Platinum | S type | ≥Φ3mm | 1100℃ | 1300℃ | 0~1300℃ | ±2.5℃ or ±0.75%t |
Nickelchromium - Copper nickel | E type | ≥Φ3mm | 600℃ | 700℃ | 0~700℃ | ±2.5℃ or ±0.75%t |
Nickel chromium - Nickel silicon | K type | ≥Φ3mm | 800℃ | 950℃ | 0~900℃ | ±2.5℃ or ±0.75%t |
Iron - constantan | J type | ≥Φ3mm | 500℃ | 600℃ | 0~600℃ | Not specified |
Copper - Copper nickel | T type | ≥Φ3mm | 350℃ | 400℃ | <-200℃ | Not specified |
-40~350℃ | ±1.0℃ or ±0.75%t |
2. Thermal response time of thermocouple
Sheath diameter (mm)
| Thermal response time (s) |
Shell type | Insulation type |
2.0 | 0.4 | 0.5 |
3.0 | 0.6 | 1.2 |
4.0 | 0.8 | 2.5 |
5.0 | 1.2 | 4.0 |
6.0 | 2.0 | 6.0 |
8.0 | 4.0 | 8.0 |
3. Thermocouple wire structure chart

4. Selection chart
Branch number | Installing form | Mode of connection | Working end form | Multipoint type | Additional device | Sheath diameter | Sheath length |
B1: Single branch; B2: Double branch | I1: No fixed device; I2: Fixed card sets of thread joint; I3: Movable card sets of thread joint; I4: Fixed card sets of flange; I5: Movable card sets of flange | C0: Simple terminals; C3: Standard waterproof protection head; C4: Explosion-proof protection head; C5: Standard plug; C6: Aviation plug; C7: Handheld; C8: Small waterproof protection head; C9: Direct lead wire | W1: Insulation type; W2: Shell type; W3: Open end type | M3: 3 points; M4: 4 points; M5: 5 points; M6: 6 points | S: Sanitary chuck; H: Heat collector | D3: Φ3; D4: Φ4; D5: Φ5; D6: Φ6; D8: Φ8 | Φ3: 50~15000mm; Φ4: 50~10000mm; Φ5: 50~4000mm; Φ6: 50~2000mm; Φ8: 50~1000mm |
5. Thermocouple installation diagram
6. Clip sleeve threaded joint dimension

Armoured thermocouple | Φ8 | Φ6 | Φ5 | Φ4 | Φ3 | Φ2 and below |
Fixing device number and size |
M | M16*1.5 | M12*1.5 |
S | 22 | 19 |
Tips: Extension wire of thermocouple
Extension wire of thermocouple is often constituted by alloy wire, insulating layer, protective jacket and shielding layer of extension wire. Within the normal temperature range below 100%C, extension wire has the same character as nominal value of thermal electromotive force of matched thermocouple. And it can extend the reference junction of thermocouple when connecting with thermocouple. Extension wire can be divided into extension type and compensation type. Its advantage is to improve flexibility of circuit and make wiring convenient. At the same time, it can adjust line resistance and prevent outside interference. What’s most important is that it can reduce cost of circuit.
T type thermocouple has the highest accuracy and lowest price in base metals. Sheath thermocouple have shielded thermocouple wire of common length 500mm and sheath diameter Ф3~Φ8mm, with flexibility, high pressure resistant, fast thermal response time and long operating life. T type thermocouple can directly measure the temperature of liquid, vapor, gas medium and solid surface in the range of -200~+350 ℃ in various production processes.