Intrinsically Safe Infrared Temperature Sensor, ATEX and IECEx Certified


  • Temperature range: -20°C to 1000°C
  • ATEX and IECEx certified up to Zone 0 (gas) and Zone 20 (dust)
  • TIIS certified for use in Japan
  • 4-20 mA output, two-wire, loop-powered
  • Supplied with up to 25 m cable
  • Cable may be extended even further (subject to safety requirements) - cable runs could extend all the way back to the control room
  • Stainless steel 316 housing, ideal for offshore applications

Hazardous Area Classification

ATEX Classification
IECEx Classification (Gas)
Ex ia IIC T4 Ga
IECEx Classification (Dust)
Ex ia IIIC T135°C IP65 Da
Ambient Temperature Rating
-20°C ≤ Ta ≤ 70°C
Maximum DC Input Voltage
Ui = 28 V
Maximum Input Current
Ii = 93 mA
Maximum Input Power
Pi = 650 mW
Maximum Internal Capacitance
Ci = 8 nF
Maximum Internal Inductance
Li = 0 mH
ATEX Certificate Number
CML 14ATEX2079
IECEx Certificate Number
IECEx CML 14.0032
TIIS Certificate Number

The ExTemp is an intrinsically safe pyrometer. It measures the temperature of surfaces in hazardous areas without contact, and provides a direct 4-20 mA output. It is certified to ATEX, IECEx and TIIS standards.

Explosion proof pyrometers typically have bulky, expensive housings, however because the ExTemp uses Intrinsic Safety as the method of protection, it is compact and low-cost.

General Specifications

Temperature Range
Configurable from -20°C to 1000°C via optional USB adapter; pre-set to a choice of ranges between these limits (see Ordering)
Maximum Temperature Span
Minimum Temperature Span
4 to 20 mA
± 1°C or 1%, whichever is greater
± 0.5°C or 0.5%, whichever is greater
Emissivity Setting Range
0.20 to 1.00 (pre-set to 0.95)
Emissivity Setting Method
User configurable via USB interface
Response Time, t90
240 ms (90% response)
Spectral Range
8 to 14 μm
Supply Voltage
12 to 24 V DC ± 5%
Maximum Current Draw
25 mA
Maximum Loop Impedance
See Application Guide (available separately)

Field of View Diagrams

Note: The given measured spot size contains 90% of the energy detected by the sensor. We normally recommend the target is at least twice as large as the given measured spot for maximum accuracy. Sensors may be used at longer distances than the above diagrams show. There is no maximum measurement distance in clean air; this is because Calex sensors detect only the wavelengths of infrared radiation that are not absorbed by the atmosphere.

Mechanical Specifications

Stainless Steel 316
Major Dimensions
Ø 20 mm x length 150 mm (see Installation)
M20 x 1.5 mm thread, length 46 mm, supplied with two mounting nuts
Cable Length
5 m, 10 m or 25 m as standard (custom lengths are also available)
Weight with 5 m Cable
475 g

Environmental Specifications

Environmental Rating IP65 (NEMA 4)
Ambient Temperature Range 0°C to 70°C (Operating range)
Relative Humidity Max. 95% non-condensing
CE Marked Yes
RoHS Compliant Yes

The ExTemp’s IIC T4, IIIC T135°C, ATEX and IECEx rating makes it suitable for many applications in hazardous areas, including:

Typical Applications

Petrochemical - condition monitoring
Bearing, gearbox and motor housing surface temperatures in refineries and chemical plants can be monitored without contact, eliminating the need to replace contact probes that are easily damaged by vibration.
Petrochemical - liquid storage and processing
The sensor can be positioned in a Zone 0 environment such as the top of a tank of hazardous liquid or reactor, to measure the surface temperature of the liquid.
Dust in pulp, paper and packaging plants can create a fire and explosion hazard. The ExTemp intrinsically safe pyrometer can be used for paper web temperature measurement and condition monitoring in ATEX and IECEx classified hazardous areas.
Coal conveyors
The ExTemp's fast 240 ms response time makes it ideal for measuring the surface temperature of coal on conveyors, as well as other bulk materials where there is an explosive dust hazard.
Gas cylinder filling
The surface temperature of cylinders of explosive gases is monitored with the ExTemp as they are filled. The Group IIC, T4 classification makes it suitable for almost all gases including propane, butane, hydrogen and acetylene. The temperature of each cylinder is measured on the filling rig to help detect fault conditions in filling, to calculate the final filled volume (in conjunction with the pressure), to ensure the volume is repeatable, and to improve the filling rate.
Automotive painting
Solvents in automotive painting can create a gas explosion risk. The intrinsically safe ExTemp may be used to monitor the temperature of containers and vessels, the surface temperature of liquids and powders, and the temperature of painted surfaces.
The ExTemp's 316 stainless steel housing and intrinsically safe certification makes it well-suited for use on offshore platforms. As well as measuring the temperature of surfaces on the rig, it can be used to measure the temperature of the sea surface.

More information about the electrical installation of the ExTemp, including pin numbering for the MTL 5541 isolator, is available in the data sheet, manual, and Application Guide. See “Media” for more information.

Electrical Installation

Dimensions (mm)

Loop Configuration Tool (USB Adapter)

All ExTemp models are fully configurable via the optional USB adapter (to be used in the safe area). The included Windows-compatible configuration software allows the user to rescale the 4-20 mA output, adjust the emissivity setting, and configure averaging, hold processing and reflected energy compensation. The adapter is connected to the measurement loop via mini-hook connectors.

Air Purge Collar

The air purge collar is used to keep dust, fumes, moisture and other contaminants away from the lens. Air flows into the fitting on the side and out of the aperture at the front.

Fixed Mounting Bracket

The L-shaped fixed mounting bracket offers a rigid support for the sensor and allows fine rotational adjustment about one axis.

Adjustable Mounting Bracket

The adjustable mounting bracket consists of a fixed mounting bracket plus another L-shaped bracket. When assembled as shown, the adjustable mounting bracket offers a rigid support for the sensor and allows fine two-axis adjustment.

PID Controllers and Indicators

The ExTemp may be connected to any of our Pixsys indicating controllers for temperature display, PID control and alarm relay outputs. Our panel-mount PID controllers, such as the ATR121 (pictured) are priced from just £72. These indicating controllers are not ATEX or IECEx certified and may only be used in the safe area.

Ordering Information