Working Principle
The purge-type thermocouple operates by introducing an inert gas—typically nitrogen or argon—into the protective sheath of the thermocouple. This purging process expels corrosive gases or contaminants from the sheath, reducing chemical attack on the sensing element. As a result, the thermocouple achieves longer service life and higher measurement reliability in aggressive environments.
Application Fields
- Ammonia synthesis systems (e.g., 300,000-ton synthetic ammonia plants)
- Petrochemical and fertilizer production
- High-temperature, high-pressure reactors
- Gas pipelines with hydrogen, carbon monoxide, or sulfur compounds
- Any environment requiring protection from corrosive or reactive gases
Structure and Materials
- Thermocouple Type: K, N, J, or other types as required
- Sheath Material: Inconel 600, stainless steel (304/316L), or special alloys
- Protection Tube: Available in single or double-layer construction
- Gas Inlet Connection: Threaded or welded interface for nitrogen or other purge gases
- Insulation: High-purity ceramic or mineral insulation
- Electrical Connection: Terminal block or plug (customizable)
Features and Advantages
- Purge System Design
Inert gas is continuously or periodically flushed into the protective sheath to remove reactive gases. - Extended Lifespan
Reduced corrosion and oxidation dramatically increase the thermocouple’s usable life. - High-Temperature Resistance
Designed for continuous operation at temperatures up to 1000°C (or higher, depending on materials used). - Enhanced Accuracy
Cleaner sensing environment minimizes measurement error due to environmental interference. - Robust Construction
Engineered for durability in high-pressure, high-vibration, and chemically aggressive conditions. - Customizable Configuration
Dimensions, thermocouple type, sheath material, and purge method can be tailored to user requirements.
Technical Parameters
- Temperature Range: 0 ~ 1200°C (depends on thermocouple type)
- Accuracy Class: Class I or II (IEC 60584)
- Gas Inlet Thread: NPT1/4″, NPT1/2″, M20×1.5 (customizable)
- Pressure Resistance: Up to 10 MPa
- Electrical Output: Standard thermocouple millivolt signal