Intrinsically Safe Infrared Temperature Sensor for High Ambient Temperatures, ATEX, IECEx, JapanEx and UKCA Certified


  • Temperature range: -20°C to 1000°C
  • Sensing head for use in ambient temperatures up to 180°C
  • ATEX, IECEx and UKEX certified up to Zone 0 (gas)
  • JapanEx certified
  • 4-20 mA output, two-wire, loop-powered
  • Optional RS-485 network adapter and USB configuration tool
  • Supplied with 5 m, 10 m or 25 m sensing head cable
  • Stainless steel 316 housing, ideal for offshore applications
  • Not designed or approved for fever detection

Hazardous Area Classification

Main Enclosure
Ambient Temperature Rating: -20°C ≤ Ta ≤ 70°C
ATEX Classification: Ex II 2 G
IECEx Classification (Gas): Ex ia [ia Ga] IIC T4 Gb
Sensing Head (ambient temperatures below 115°C)
Ambient Temperature Rating: -20°C ≤ Ta ≤ 115°C
ATEX Classification: Ex II 1 G
IECEx Classification (Gas): Ex ia IIC T4 Ga
Sensing Head (ambient temperatures below 180°C)
Ambient Temperature Rating: -20°C ≤ Ta ≤ 180°C
ATEX Classification: Ex II 1 G
IECEx Classification (Gas): Ex ia IIC T3 Ga
Maximum DC Input Voltage
Ui = 28 V
Maximum Input Current
Ii = 93 mA
Maximum Input Power
Pi = 0.651 W
Maximum Internal Capacitance
Ci = 5.17 nF
Maximum Internal Inductance
Li = 1.99 µH
ATEX Certificate Number
IECEx Certificate Number
IECEx CML 22.0001X
JapanEx Certificate Number
CML 22JPN2009X
UKCA Certificate Number

The ExTempMini 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, UKCA and JapanEx standards.

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

General Specifications

Measurement Temperature Range
-20°C to 1000°C (see table of Model Numbers)
Two-wire 4 to 20 mA (loop powered)
Maximum Temperature Span
Minimum Temperature Span
± 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 optional USB / RS-485 adapters
Response Time, t90
240 ms (90% response)
Spectral Range
8 to 14 μm
Supply Voltage
12 to 24 V DC ± 5%
Minimum Sensor Voltage
11.4 V DC
Maximum Current Draw
25 mA

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 the ExTempMini detects only the wavelengths of infrared radiation that are not absorbed by the atmosphere.

Mechanical Specifications

Main Enclosure: Painted Aluminium
Sensing Head: Stainless Steel 316
Major Dimensions
Main Enclosure: 99 x 65 x 35 mm
Sensing Head: Ø 20 x length 69 mm including cable gland (see Dimensions)
Main Enclosure: 2 x mounting holes, use M4 socket head screws
Sensing Head: M20 x 1.5 mm thread, length 20 mm, supplied with two mounting nuts
Cable Length (Sensing Head)
Choice of 5 m, 10 m or 25 m factory-fitted. Contact Calex for information about extending cable.
Weight with Cable
475 g (5 m cable), 625 g (10 m cable), 1075 g (25 m cable)
Cable Connections
Removable screw terminal blocks (see Connections). Conductor size 22 AWG to 14 AWG (0.326 mm2 to 2.08 mm2)
Output Cable Gland
Suitable for cable diameters 3.5 to 7.0 mm

Environmental Specifications

Environmental Rating
Main Enclosure and Sensing Head: IP65 (NEMA 4)
Ambient (Operating) Temperature Range
Main Enclosure: 0°C to 70°C
Sensing Head: 0°C to 180°C
Ambient Pressure Range
Main Enclosure and Sensing Head: 80 kPa (0.8 bar) to 110 kPa (1.1 bar)
Relative Humidity
Main Enclosure and Sensing Head: Max. 95% non-condensing
CE Marked
RoHS Compliant

Electromagnetic Compatibility Standards

Conforms to EN 61326-1, EN 61326-2-3 (Industrial).

The ExTempMini’s ATEX, IECEx, UKCA and JapanEx certification makes it suitable for many applications in hazardous areas involving gas.

Applications include:

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 sensing head can be positioned in a Zone 0 environment such as the top of a tank of hazardous liquid or chemical reactor, to measure the surface temperature of the liquid, in conjunction with suitable air purging or protective viewport.
Gas cylinder filling
The surface temperature of cylinders of flammable gases is monitored with the ExTempMini as they are filled. The Group IIC, T4 (or T3 depending on ambient temperature) classification of the sensing head 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 lead to the presence of a hazardous gas Zone. The intrinsically safe ExTempMini may be used to measure the temperature of containers and vessels, the surface temperature of liquids, and the temperature of painted surfaces.
The stainless steel 316 housing of the ExTempMini's sensing head, and its intrinsically safe certification, make it well-suited for use on offshore platforms.

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

Electrical Installation

Connections: ExTempMini (also showing optional USB adapter model LCT) (below)

Network layout: ExTempMini with optional RS-485 interface, model LCT-485 (below)

Dimensions (mm)

RS-485 Network Interface

This DIN rail-mounted unit provides RS-485 Modbus RTU Slave communications for one ExTempMini sensor. It must only be connected on the safe side of the isolator or barrier. It allows up to 224 ExTempMini sensors to be connected together in a network.

Model: LCT-485

Loop Configuration Tool (USB Adapter)

All ExTempMini models are fully configurable via the optional USB adapter (must only be connected on the safe side of the isolator or barrier). The free 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.

Model: LCT

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.

Models: APM (for sensors with 20:1 optics)
APMW (for sensors with 2:1 optics)

Fixed Mounting Bracket

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

Model: FBL

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.

Model: ABL

PID Controllers and Indicators

The ExTempMini 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 available at low cost. These indicating controllers are not ATEX or IECEx certified and may only be used in the safe area.

Ordering Information