The explosion-proof thermocouple is normally used together with display instruments, recording instruments and electronic computers. It directly measures the temperatures of liquid, steam and gas media and solid surfaces at production sites containing explosive mixtures, with a measurement range of 0 to 1300°C. It uses the gap explosion-proof principle: components that may generate sparks, arcs and dangerous temperatures are sealed in the junction-box cavity. If an explosion occurs in the cavity, flame and temperature are quenched and cooled through the joint-surface gap, preventing transmission outside the cavity.
- Temperature measurement at production sites containing explosive mixtures.
- Temperature measurement of liquid, steam and gas media.
- Solid surface temperature measurement.
- Explosion-proof temperature-measurement applications used with display, recording or electronic computer systems.
- Suitable for a wide range of explosion-proof environments.
- Spring-loaded temperature-sensing element with good vibration resistance.
- Large measurement range, with a maximum of 1300°C.
- High mechanical strength and good pressure resistance.
- Junction box protection level available in IP65, IP66 and IP68.
- Available with no fixed installation, fixed thread, adjustable flange, fixed flange, fixed thread cone type, straight tube fitting type, fixed thread tube fitting type and adjustable thread tube fitting type.
- Vertical pipeline, inclined pipeline and flange installation are available.
- Single or double elements are available, in armored or assembly construction.
| Item |
Parameter |
| Applicable standards |
GB/T30429 and GB/T3836 series standards |
| Ambient temperature |
20±15°C |
| Relative humidity |
Not more than 80% |
| Test voltage |
DC 500±50 V |
| Insulation resistance between electrode and outer sleeve |
≥1000 MΩ |
| Model |
Graduation |
Class I temperature range and permissible deviation |
Class II temperature range and permissible deviation |
| WRNK |
K |
-40 to 375°C: ±1.5°C; 375 to 1000°C: ±0.004｜t｜ |
-40 to 333°C: ±2.5°C; 333 to 1200°C: ±0.0075｜t｜ |
| WRMK |
N |
-40 to 375°C: ±1.5°C; 375 to 1000°C: ±0.004｜t｜ |
-40 to 333°C: ±2.5°C; 333 to 1200°C: ±0.0075｜t｜ |
| WREK |
E |
-40 to 375°C: ±1.5°C; 375 to 800°C: ±0.004｜t｜ |
-40 to 333°C: ±2.5°C; 333 to 900°C: ±0.0075｜t｜ |
| WRFK |
J |
-40 to 375°C: ±1.5°C; 375 to 750°C: ±0.004｜t｜ |
-40 to 333°C: ±2.5°C; 333 to 750°C: ±0.0075｜t｜ |
| WRCK |
T |
-40 to 125°C: ±0.5°C; 125 to 350°C: ±0.004｜t｜ |
-40 to 133°C: ±1.0°C; 133 to 350°C: ±0.0075｜t｜ |
| WRPK |
S |
0 to 1100°C: ±1.0°C; 1100 to 1600°C: ±[1+0.003(t-1100)] |
0 to 600°C: ±1.5°C; 600 to 1600°C: ±0.0025｜t｜ |
| WRQK |
R |
0 to 1100°C: ±1.0°C; 1100 to 1600°C: ±[1+0.003(t-1100)] |
0 to 600°C: ±1.5°C; 600 to 1600°C: ±0.0025｜t｜ |
| WRRK |
B |
/ |
600 to 1700°C: ±0.0025｜t｜ |
| Temperature grouping |
Maximum surface temperature |
| T1 |
≤450°C |
| T2 |
≤300°C |
| T3 |
≤200°C |
| T4 |
≤135°C |
| T5 |
≤100°C |
| T6 |
≤85°C |
| Category |
Explosion-proof marking |
Certification authority |
| Explosion-proof thermocouple |
Ex db IIC T4…T6 Gb / Ex tb IIIC T80°C…T130°C Db |
NEPSI |
| Explosion-proof thermocouple |
Ex db IIB T4…T6 Gb / Ex tb IIIB T80°C…T130°C Db |
NEPSI |
| Intrinsic safety thermocouple |
Ex ia IIC T4…T6 Ga / Ex ia IIIC T200135°C Da |
NEPSI |
- WRN-240/241
- WRN-440/441
- WRN-74, WRN-84
- WRN-74-TH03H, WRN-74-TH02B
- Required graduation, accuracy class, single or double element, and armored or assembly construction.
- Measured medium, operating temperature, pressure and site vibration conditions.
- Site hazardous-area classification, required explosion-proof marking and temperature grouping.
- Installation method, protective-tube material/diameter, overall length L, insertion depth I and connection dimensions.
- Whether a straight connector or matched thermal installation sleeve is required.
- Display instruments, recording instruments and electronic computers: explosion-proof thermocouples are normally used with these products.
- Straight connector and thermal installation sleeve: the installation diagrams show them for vertical, inclined pipeline and flange mounting.
