RTD temperature sensor

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Product overview

Intended use
Temperature measurement in potentially explosive atmospheres (gas and dust zones).

Certification
Certified in accordance with the ATEX Directive 2014/34/EU.

Temperature sensors
Explosion-proof temperature sensors are available as resistance temperature detectors (RTDs) or thermocouples, in mineral-insulated, tubular or cable designs, and as multipoint variants depending on application requirements.

Types of ignition protection (selection)

• Ex i (Series R0/T0 to R8/T8): Certified for connection to intrinsically safe circuits category ia. Electrical limits: Ui = 30 VDC, Ii = 101 mA, Pi = 750 mW.
• Ex d (Series R9/T9): Flameproof enclosure for high-temperature applications. Electrical limits: Umax = 5 V, Imax = 2 mA; suitable for measurements up to 1800 °C (series dependent).
• Ex e (Series RE4/TE4, RE5/TE5, RE6, RE7, RE8/TE8): Increased safety. Electrical limits: Umax = 30 V, IN = 2 mA, Pmax = 102 mW. A current limiter is required for overload protection (Imax = 1.7 × IN; IN per IEC 60127).
• Ex ec / Ex tc (Series RX/TX, RN/TN): Additional protection types and special designs are part of the product range.

Areas of application

• Agriculture
• Automotive industry
• Chemical industry
• Control measurements
• Energy production
• Food industry
• Hydrogen handling
• Laboratories and pharmaceutical industry
• Liquids
• Machines and devices
• Pipelines
• Plastics industry
• Shipbuilding industry
• Tanks and containers
• Technological processes
• Waste processing and recycling

Ex-zones (definition)
Zone 0: Area where an explosive atmosphere of flammable gases or vapours is present continuously or for long periods.
Zone 1: Area where an explosive atmosphere is likely to occur in normal operation.
Zone 2: Area where an explosive atmosphere is unlikely to occur in normal operation and, if it does, only infrequently and for a short period.
Zone 20: Area where a cloud of combustible dust in air is present continuously or for long periods.
Zone 21: Area where a cloud of combustible dust is likely to occur in normal operation.
Zone 22: Area where a cloud of combustible dust is unlikely to occur in normal operation and, if it does, only infrequently and for a short period.

ATEX product series

• Series R0/T0 (Ex i): Intrinsically safe measuring inserts Ø 3 mm, 4.5 mm, 6 mm; terminal block or flying leads variants. Use in Ex areas requires suitable protective thermowell or connection housing (min. IP54).
• Series R1/T1 to R3/T3 (Ex i): Protection tubes with wall thickness ≥ 1 mm for reliable zone separation (Zone 0/20); tapered tips available to reduce thermal response time; standard process connections or weld-in sockets.
• Series R4/T4 (Ex i) and RE4/TE4 (Ex e): Designed for Zone 1 (gas) and Zone 21 (dust); closed protection tubes for short response times; variants without connection, adjustable or permanently welded connections. Process connections do not provide zone separation.
• Series R5/T5 (Ex i) and RE5/TE5 (Ex e): Measuring inserts without additional protection tube; diameters Ø 3/4.5/6 mm; fixed threaded fittings or compression fittings; Ex approvals: Ex i Zone 1 and Ex e Zone 1/21.
• Series R6/T6 and RE6 (Ex e): Compact cable sensors, tubular or mineral-insulated; flexible, suitable for hard-to-access locations; Ex i Zone 1, Ex e Zone 1/21.
• Series R7/T7 and R8/T8: Cable sensors with extended approvals including Zone 0/20; straight, angled or mineral-insulated versions; zone separation via approved IP67 compression fittings.
• Series RE7 and RE8/T8 (Ex e): Approved for Zone 1 and Zone 21; permanently attached cable and protection tube variants; mineral-insulated options available.
• Series R9/T9 (Ex d): High-temperature sensors with flameproof enclosure; measurements up to 1800 °C (series dependent); protective assemblies in ceramic or metal (protective assembly may be customer-supplied).
• Series RN/TN (Ex ec), RT/TT (Ex tc), RX/TX (Ex i): Special designs for Ex ec (Zone 2), Ex tc (Zone 22) and customized passive apparatus (Ex i, Zone 1); tube-skin and multipoint options available.

ATEX sensors with electrically conductive coating
Coated protection assemblies are available for chemically aggressive environments and enhanced explosion-protection demands. Coatings provide electrically dissipative properties to increase sensor service life.

• PFA ultra+ (light grey): Layer thickness ≈ 500–700 µm; FDA and EU compliant for food contact up to ≈ 180 °C; suitable for vacuum; temperature resistant up to ≈ 210 °C (non-stick) and ≈ 150 °C for chemical protection depending on chemicals. Applicable to Zones 0/1/2 and 20/21/22.
• E-CTFE (black): Layer thickness ≈ 500–700 µm; not FDA-compliant; suitable for vacuum; temperature resistant up to ≈ 120 °C depending on chemicals; applicable to Zones 0/1/2 and 20/21/22 with process constraints.
• adcoat 33/2100 D: Layer thickness ≈ 180–300 µm or 720–1200 µm; temperature resistant up to 260 °C; suitable for vacuum; not FDA-compliant; applicable to Zones 0/1/2 and 20/21/22.

Technical specifications / characteristics

• Certification: ATEX Directive 2014/34/EU.
• Intended use: Temperature measurement in potentially explosive atmospheres (gas and dust zones).
• Sensor types: RTDs and thermocouples; mineral-insulated or tubular designs; cable sensors and multipoint variants.
• Typical measuring insert diameters: 3 mm, 4.5 mm, 6 mm.
• Ex i electrical limits: Ui = 30 VDC, Ii = 101 mA, Pi = 750 mW.
• Ex d electrical limits: Umax = 5 V, Imax = 2 mA; high-temperature approvals up to 1800 °C for specific series.
• Ex e electrical limits: Umax = 30 V, IN = 2 mA, Pmax = 102 mW; current limiter required for overload protection (Imax = 1.7 × IN).
• Protection rating example: min. IP54 for certain installations; IP67 compression fittings for zone separation in some series.
• Protection tube wall thickness for zone separation: ≥ 1 mm for series R1–R3.
• Coating options: PFA ultra+, E-CTFE, adcoat 33/2100 D with specified layer thicknesses and temperature resistances.

Installation and zone separation note
Use in Ex areas requires appropriate protective thermowells or connection housings. Some process connections do not constitute zone separation; correct implementation of zone separation (e.g., welding sleeves) is the responsibility of the installer or operator.