ATEX Exia Resistance Thermometers

Atex Exd Thermocouple

Resistance Thermometers with Ignition Protection Exia

These immersion and insertion resistance thermometers comprise a rugged installation fitting made of stainless steel with thread, flange or weld-on connection, a painted aluminium connection head, and a removable measuring element (except models TWL-ST, -SN, and -SA). The insert can be replaced without emptying the installation (with the exception of TWL-ST, -SN and -SA), because the customised thermowell remains in the installation and seals the process. The instruments are supplied with ignition protection Exia as standard so can be installed in relevant hazardous areas.

A 2, 3 or 4 wire Pt100 rated to IEC 751, category A or B is fitted in each measuring insert. Alternatively, the 2 or 3 wire versions can be designed as a single or double Pt100 thermometer. Optional head transmitters, encapsulated in epoxide resin inside the connection head, are available to transmit measuring signals noise-free over long distances, with either a  4-20 mA signal , or with HART® protocol or PROFIBUS®/Fieldbus.  The immersion length, connection head, materials, process connection and tolerance classes can all be customised to meet your requirements.

These resistance thermometers with thread-, flange- or weld-on connection are ideal for temperature measurement in liquids, solids and gaseous media. The reliable water tightness of these installation methods is critical when dealing with gauge pressure and vacuum.  Applications include the air-conditioning and cooling industry, and heating-, furnace-, mechanical- and apparatus-construction. Supplied with ignition protection Exia, these ATEX Exia resistance thermometers are perfect in hazardous areas.

Please ask for more information.


  • Measuring range: -80°C to +600°C
  • Pt100 2, 3 or 4 wire: Insertion and Immersion, Class A or Class B
  • Output: Resistance or Analogue 4-20 mA
  • Thermowells: according to DIN 43772
  • Option: head transmitter with HART®-protocol or PROFIBUS®/Fieldbus, display
  • Connection: thread, flange, weld-on sleeve
  • Bulb Material: stainless steel
  • Applications: ATEX, ignition protection Exia

Technical Data

Measuring Range:  -80ºC to +600 ºC (-40°C to +85°C TWL-ST)
Sensor: Pt100 Single or double sensor (1 x Pt100 or 2 x Pt100)
Accuracy: Class A or Class B (others on request)
Ambient temperature: -40 … +150 °C (-40°C to +85°C TWL-ST) with ceramic terminal base (without transmitter)
-40 … +85 °C with transmitter
-40 … +85 °C for room temperature sensor
Operating pressure: max 250 bar (depending on TWL version, see order details)
Connection head: form B with chain except TWL-ST: Aluminium or polycarbonate connection head
TWL-SN and TWL-SA: without connection head
Materials – Sensor: stainless steel 1.4404 (except TWL-D and TWL-ST, others on request)
Materials – Neckpipe: stainless steel 1.4404(except TWL-D and TWL-ST, others on request)
Materials – Connection head: aluminium, painted (TWL-ST: Polycarbonate)
Materials – Terminal base: ceramic (without transmitter)
Process Connection : G ½ male, G 1 male
flange DN25
weld on sleeve Ø 24 h7, others on request
Sensor wiring: 2, 3 or 4 wire
Protection: connection head IP 65
sensor IP 68
ATEX-approval: Ex II 1 GD Exia IIC T4…T6
ExiaD 20 IP65
Head transmitter – Output: analogue output 4-20 mA
Head transmitter – Communication: HART®-protocol, Profibus®/ Fieldbus
Head transmitter – Minimum meas. span: standard transmitter 25ºK
transmitter with HART® 10ºK
transmitter with Profibus®/Fieldbus 5ºK
 Head transmitter – Supply voltage: 8 – 35 VDC for standard transmitter and transmitter with HART®
9 – 32 VDC for transmitter with Profibus®/ Fieldbus