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: Advantages of sheath thermocouple
Sheath thermocouple is a solid integrity which is formulated by thermocouple wire, insulating material and metal sheath through stretching or rotary swaging. The diameter of sheath thermocouple can be processed small and long.
- Thermal inertia or thermal response time of thermocouple is short. It has significant importance to modern industrial production process that adopts computer to detect and control.
- It saves materials, especially precious metal, thus reducing cost.
- Thermocouple has great flexibility, thus it can be applied to measure temperature of industrial production equipment with complex structure.
- Long service life
- Sheath thermocouple has favorable mechanical property, thus it can resist strong vibration and impact. It can be suitable for temperature measurement of production equipment with vibration and impact.
- It has high pressure resistant and has favorable insulation in high temperature. Thus it is suitable for temperature measurement of equipment in industrial production process with high temperature or high pressure or both.
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. K type thermocouple can directly measure the temperature of liquid, vapor, gas medium and solid surface in the range of 0~950 ℃ in various production processes.