ATEX certified head type sensors "i" protection concept

with thermocouple or RTD

"CSI" and "CTI" ranges


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

"i" protection concept - Intrinsic safety - demands that a Zener barrier or a galvanic isolator limits the energy delivered to the circuit in order to prevent any arc or spark from arising.

There are 2 levels of protection:

  • "ib": the equipment is able to resist one fault of its safety components. "ib" concept applies to zone 1 or 21 and 2 or 22.
  • "ia": the equipment is able to resist two faults of its safety components. "ia" concept is compulsory in zone 0.

Zoning lays under the end user's responsibility. More information about zone classification...

Such temperature sensors are mostly used in surroundings where the reading 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 fxation devices (flange or welded or sliding fitting) allow perfect tightness.

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 reliable use. The essential features defining the sensor performance are tightness, resistance to vibrations, corrosion, shocks, wear and tear and to any disturbing factors.

Mechanical resistance and response time, which may 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 

NF EN 60751 IEC 60751
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


Cable-type temperature sensors with "i" 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 6427X are complied with. Download certificate...

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


The most common dimensions are:

  • Thermic element length: 3, 4.5, 6, 8 mm
  • "Lt" length under head:
  • "L" length under fitting:
  • Extension length:


Sensing element :
  • Platinum 100 Ohms at 0°C
      1x, 2x,
      2, 3 or 4-wire assembly
  • Simple or double thermocouple with ungrounded hot junction
      types: K, J, T, N, S, E, B, R, C


protecting tube :

•  metallic
•  solid drilled
•  mechanically welded

insulation :

•  magnesium oxide (MgO), standard or high purity


sheath :

•  replaceable or fixed thermic element:
   diameters: 3, 4.5, 6, 8 mm

•  materials: 301L SS, 316L SS, 310 SS, alloy 600

cable gland :
  • PG16 cable gland


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.