ATEX certified head type temperature sensor "d" protection concept


with thermocouple or RTD probe


Such temperature sensors are designed for use in potentially explosive atmospheres in compliance with the 94/9/CE European Directive.

"d" protection concept - flameproof enclosure - means that any explosion has to be confined inside the sensor thanks to a very robust envelope.

"d" protection concept is suitable for zone 1 or 21, and 2 or 22 but it is not to be used in zone 0. Zoning lays under the responsibility of the end user. More information about zone classification...

Such temperature sensors are mostly used in surroundings where the reading out area is at a distance from the measure taking area. The active part, either a thermocouple or a PT100, is generally protected by a metallic tube or sheath. It is either in direct contact with the measured environment or placed inside a thermowell. Connection is made through a terminal block or a transmitter protected by a connecting head. Different fixation devices (flange, welded or sliding fitting) allow perfect tightness between the zones and/or the sensor components.

The process data and the 94/9/CE Directive requirements determine the dimensional features of the thermowells which must pass overpressure tests.

Temperature range

  • Thermocouple: -40°C to +1700°C, according to thermocouple type. More information...
  • PT100: -200°C to +500°C

Warning: The user must take all precautionary measures to ensure that the calorific transfer of the sensor does not reach the self-ignition temperature of the surrounding gas or dust.

Mechanical data

The selected materials as well as the type of fixation must ensure a safe and reliable use. The essential features defining the sensor performance are tightness, resistance to vibrations, corrosion, shocks, wear and tear and resistance to any disturbing factors.

Mechanical resistance and response time, which seem opposite requirements, may be improved by reducing the sheath diameter in the active part.





 sensing element  - Class A : + 0,15 + 0,002 [t°]
 - Class B : + 0,30 + 0,005 [t°]
 Reduced tolerances on request
 thermocouple wire tolerances
 as per NF EN 60751 & IEC 751 standards
 sensor  according to type of assembly:
  2, 3 or 4 wires
 tolerances as per  UTE 46201 standard

Response time
to reach x% of the temperature scale interval (in seconds)

Diameter: 6 mm









Tests carried out without thermowell
(*)  as per UTE C46-202 standard, on a 1 x PT100 sensor, 3 wire-assembly, temperature range: –20°C + 100°C.
(**) as per UTE C46-201, on a type K thermocouple, ungrounded hot junction, inconel 600 sheath.

Applicable standards 

IEC 751
UTE 46202
UTE 46201
94/9/CE European Directive, Potentially explosive atmospheres
97/23/CE European Directive, Pressure equipment
Whenever requested by specific applications, other applicable standards are also complied with


Head type temperature sensors with "d" protection concept may be used in potentially explosive atmosphere provided that the requirements of the 94/9/CE European directive as well as our EC-type examination certificate LCIE 03 ATEX 6058X are complied with. Download certificate...

 All our ATEX temperature sensors are also GOST R - NANIO CCVE N° 7454152 certified. Download certificate...

Lengths as per customer specification:
"LT" : Thermowell length
"T" : extension length
"L" : length under flange or fitting

Stress calculation on request

Sensing element :
  • Platinum 100 Ohms at 0°C
      1x, 2x,
      2, 3 or 4-wire assembly
  • Duplex or simplex thermocouple:
      types: K, J, T, N, S, E, B, R, C


sheath :
  • fixed or replaceable thermic element:
    diameters: 3, 4.5, 6, 8 mm
    material: 301L SS, 316L SS, 310 SS, alloy 600


insulation :
Magnesium oxide (MgO)
standard or high purity

connecting head :
  • aluminium or stainless steel
  • with or without indicator
  • screwed or lever lid
  • IP54 to IP67
  • terminal block
  • standard 4-20mA transmitter, protocol Hart or Fiedbus


process connection :
  • welded or adjustable flange
  • extension between thermowell and connecting head
  • compression fitting
  • sealing fitting
  • union fitting
  • welded fitting


marking :
Marking aims at clearly identifying the use limits of the sensor. It must be readable, durable and indestructible;
- stainless steel plate chained on the head
- printed label stuck on the head

Each individual ATEX certified sensor is delivered with a French-English mounting instructions datasheet which can be provided in other languages on customer request.