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Description and application


Resistance temperature sensors are designed for contact temperature measurement of liquid and gaseous substances. They operate on the principle of dependency of the change of resistance of the sensor and the change of temperature. Resistance temperature sensors are not able to create sparks, electric arcs or high surface temperatures and the maximum permitted DC input power for the sensor is 2mW. The standard temperature range for using of the sensor in ZONE 2 is – 30 to 80 °C, which corresponds to temperature class T6, and it must not be exceeded even for a brief period in areas with the risk of explosion. By combining it with a centre holder or thermowell supplied as accessories, the sensor can be used for measuring temperature in air conditioning ducts and pipes.

The sensors are designed to be operated in a chemically non-aggressive environment, the use must be chosen with regard to temperature resistance of the head and chemical resistance of the case and head of the sensor.  



  • Manufacturer provides EU Declaration of Conformity.
  • Calibration – The final metrological inspection – comparison with standards or working instruments – is carried out for all the products. Continuity of the standards and working measuring instruments is ensured within the meaning of the Section 5 of Act no.505/1990 on metrology. The manufacturer offers a possibility to supply the sensors calibrated in SENSIT s.r.o.’s laboratory (according to requirements of the EN ISO/IEC 17025 standard) or in an Accredited laboratory.  


  • Specifications
  • Wiring diagram
  • Dimensional draft
  • Download
Sensor type NK 120EX NK 121EX NK 122EX NK 320EX NK 321EX
Type of sensing element Ni 1000/5000 Ni 1000/6180 Ni 891 Ni 10000/5000 Ni 10000/6180
Measuring range in ZONE 2 -30 to 80 °C
Max. DC measuring current 1 mA 1 mA 1 mA 0.3 mA 0.3 mA

Sensor type NK 123EX PTK 120EX PTK 220EX PTK 320EX HK 120EX
Type of sensing element T1 = Ni 2226 Pt 100/3850 Pt 500/3850 Pt 1000/3850 termistor NTC 20 kΩ
Measuring range in ZONE 2 -30 to 80 °C
Max. DC measuring current 0.7 mA 3 mA 1.5 mA 1 mA 1 mW *)

*) maximum power consumption

Measuring range in ZONE 2: -30 °C≤ Ta ≤ 80 °C
Sensing element connection 2wire, 3wire, 4wire
Recommended power supply from a PELV or SELV source
maximum input power 2mW
Time response
in accordance with EN 60751 (in flowing water > 0,2 m/s),
- for case diameter 4 mm: τ0,5 ≤ 4 s, τ0,9 ≤ 10 s
- for case diameter 6 mm: τ0,5 ≤ 9 s, τ0,9 ≤ 20 s
- for case diameter 8 mm: τ0,5 ≤ 14 s, τ0,9 ≤ 35 s
- for case diameter 10 mm: τ0,5 ≤ 25 s, τ0,9 ≤ 60 s
Insulation resistance > 200 MΩ at 500 V DC, 25 ± 3°C and relative humidity < 80 %
Electric strength 1000 V DC for 1s, 25 ± 5°C, humidity < 80 %
Ingress protection IP 66 in accordance with EN 60529
Terminal board type ceramic, recommended cross-section of the wires 0.5 to 1.0 mm2
Material of the connection head aluminum
Dimension of the connection head 83 x 83 mm
Temperature resistence of the head -30 to 90 °C
Material of the stem stainless steel DIN 1.4301, 1.4404 or 1.4571
Diameter of the stem D
4 mm, 6 mm, 8 mm, 10 mm
Standard length of stem L diameter 4 mm: 70, 120, 180, 240 mm
other diameter: 50, 70, 120, 180, 240, 300, 360 a 420 mm
Wire resistance 0.254 Ω / m (two-wire connection)
Maximum operating pressure with stem diameter 4 mm 2,5 MPa
with stem diameter 6 to 10 mm 6,3 MPa
Weight min 0.4 kg

Note: Manufacturer reserves the right to make changes in design and technical characteristics of the products. For actual information, please always contact your dealer.

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