• Introduction

Temperature sensors designed for hazardous environments often combine flameproof (Ex d) and intrinsically safe (Ex i) protection methods to ensure maximum versatility and safety in volatile atmospheres. While a flameproof enclosure is engineered to contain an internal explosion and prevent it from igniting the surrounding flammable gases, intrinsic safety limits the electrical energy within the circuit to levels insufficient to cause ignition by either sparking or thermal effects. By integrating these two philosophies, manufacturers provide a robust solution where the sensor’s rugged housing provides mechanical and explosion-containment durability, while the internal electronics operate on low-power signals that are inherently incapable of starting a fire. This dual-rated approach is essential for critical applications in oil and gas refineries, chemical processing plants, and underground mining, where accurate thermal monitoring must be maintained without compromising the integrity of the facility’s safety zones.

  • Working Principles

The working principle of dual-rated temperature sensors hinges on the simultaneous application of containment and energy limitation to prevent atmospheric ignition. For flameproof (Ex d) protection, the sensor is housed in a heavy-duty enclosure with precision-engineered “flame paths” that allow internal gases to escape only after being cooled below the ignition temperature of the external environment. Simultaneously, the intrinsically safe (Ex i) principle operates by utilizing zener barriers or galvanic isolators to restrict the current and voltage (V) reaching the sensing element—typically a Resistance Temperature Detector (RTD) or Thermocouple. This ensures that even in a short-circuit scenario, the thermal energy generated by the electrical signal remains below the minimum ignition energy (MIE) of the surrounding hazardous vapors. Essentially, the sensor measures temperature by detecting changes in electrical resistance or millivolt output, while the mechanical housing acts as a physical bunker and the circuitry acts as an electrical throttle, creating a fail-safe system for volatile industrial zones.

  • Applications

In hazardous industrial environments, dual-rated temperature sensors are critical for maintaining safety and process efficiency. Their applications span industries where flammable substances are processed, stored, or transported:

  • Oil and Gas Refineries

  • Chemical and Petrochemical Plants

  • Offshore Drilling Platforms

  • Pharmaceutical Manufacturing

  • Underground Mining Operations

  • Power Generation

  • Fuel Storage and Distribution Terminals

  • Wastewater Treatment

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Flameproof Headsensor

In stock

SKU: Exd
Flameproof temperature sensor with the head connected to a replaceable measuring insert for liquid and gaseous media. The complete unit is certified as flameproof (explosion proof Exd) for applications in hazardous area. Temperature ranges from -200 up to 1200°C. Different Mounting options The spring-loaded insert ensures an excellent connection with the bottom of the sensor thermowell. Flameproof - Exd approval for dust and gases. view products download pdf datasheet
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intrinsically safe Cablesensor Exia

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SKU: TOPE exi
Intrinsically safe temperature sensor suitable for measurement of pipes and shafts, district heating substations, high pressure solutions,... Sensor has a pipe band clamp, compression fitting, fitting and moving fitting with thread, Exia approval for application in hazardous area. download pdf datasheet
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intrinsically safe Headsensor

In stock

SKU: Exia
Explosion proof temperature sensor with a replaceable measuring insert and connection head for liquid and gaseous media. The complete unit is certified as intrinsically safe, (Exia) for applications in hazardous area. Temperature ranges from -200 up to 1200°C. Different Mounting options. The spring-loaded insert ensures an excellent connection with the bottom of the sensor thermowell. view products download pdf datasheet
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TOPGB-1..Exi, TTKGB-1..Exi, TTJGB-1..Exi

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Temperature sensor suitable for measurement of liquid and gaseous media. It has a replaceable measuring insert adequate for various industrial applications. Replacement of the measuring insert does not cause the technological installation damage. Spring-loaded insert ensures an excellent connection with the bottom of the sensor thermowell. Temperature sensor has ATEX approval for application in hazardous area: I M1 Ex ia (with connection head N1) II 1/2G Ex ia IIC T6 II 1/2D Ex ia IIIC T85°C cable gland II 2GD Ex eb IIc, Ex ta IIIC (for the cable 5÷10mm).
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TOPGB-Exd, TTKGB-Exd, TTJGB-Exd

In stock

Temperature sensor suitable for measurement of liquid and gaseous media. It has a replaceable measuring insert adequate for various industrial applications. Replacement of the measuring insert does not cause the technological installation damage. Spring-loaded insert ensures an excellent connection with the bottom of the sensor thermowell. Temperature sensor has ATEX approval for application in hazardous area: I M2 Ex d I Mb (with connection head NS) II 2G Ex d IIC T6 Gb II 2D Ex t IIIC T85ºC Db IP66.