Working Principle
The Explosion-proof Multipoint Thermocouple operates on the Seebeck effect, in which thermoelectric voltage is generated at the junction of two dissimilar metals when there is a temperature difference. This device integrates multiple thermocouple junctions along a single probe or cable, enabling simultaneous temperature monitoring at various depths or positions within a process system.
The explosion-proof design includes flame-arresting enclosures and sealed joints, ensuring that no sparks, arcs, or high temperatures from internal components can ignite the surrounding flammable atmosphere. This makes it ideal for Zone 1 and Zone 2 hazardous areas.
Typical Applications
Explosion-proof multipoint thermocouples are widely used in hazardous industrial environments that require both precise multi-zone temperature monitoring and strict explosion protection:
- Petrochemical reactors (fixed-bed, fluidized-bed reactors)
- Oil & gas pipelines
- Storage tanks containing volatile liquids
- Chemical processing vessels
- Pharmaceutical reactors
- Energy and power generation units
- Dust-prone areas like coal mills or biomass boilers
These thermocouples improve process control and ensure operational safety in locations where explosive gas or dust atmospheres may be present.
Structure & Materials
- Thermocouple Elements
- Types: Type K, J, N, E, or T, selected based on temperature range and chemical compatibility
- Multiple sensors embedded at custom-defined positions (e.g., every 0.5 m or 1 m)
- Protective Sheath / Probe
- Materials:
- 304/316L Stainless Steel – for general industrial use
- Inconel 600/625 – for high-temperature or corrosive environments
- Ceramic (optional) – for extremely high temperatures
- Designed to resist abrasion, pressure, and chemical attack
- Materials:
- Insulation
- Mineral Insulated (MI) cables for high thermal conductivity and electrical insulation
- Ensures long-term signal stability even under thermal shock
- Explosion-proof Terminal Head
- Housing Material: Aluminum alloy or stainless steel
- Protection Grade: Ex d IIC T6 Gb / Ex tD A21 IP65
- Built with flameproof joints and cable sealing glands to isolate ignition sources
- Mounting Options
- Flange, threaded, or compression fittings
- Supports vertical or horizontal installations
- Optional Accessories
- Temperature transmitters (4–20 mA or HART output)
- Digital signal concentrators
- Thermowells for replaceable installation
Technical Features & Benefits
- Explosion-proof certified for hazardous gas and dust zones
- Multi-point sensing enables precise thermal profiling
- Durable and corrosion-resistant for long service life
- High signal accuracy and response speed
- Compact design reduces wiring complexity and installation time
- Customizable configuration to fit a wide range of applications