Purge Type Thermocouple

In coal chemical ammonia synthesis units, refinery sulfur recovery plants, and metallurgical hot blast furnaces, the biggest threat to thermocouples is not just high temperature. The real danger comes from reducing or corrosive gases in the process. Hydrogen, carbon monoxide, ammonia, and sulfur compounds penetrate the protection tube at high temperatures. These gases cause "poisoning" and embrittlement of the thermocouple wires. Ordinary thermocouples last only two to three months in these conditions. Anhui Tiankang's purge type thermocouple solves this industry-wide problem with a clever gas purging design.

The purge type thermocouple creates a protective gas curtain around the sensing element. There is a small annular gap between the sheathed core and the outer tube. Clean nitrogen or argon gas flows through this gap at a slight positive pressure of about 0.1MPa. This purge gas sweeps harmful media away from the thermocouple wires. The result is a clean atmosphere around the sensing element that prevents chemical attack.

Purge type thermocouple technology delivers remarkable life extension. In the same highly corrosive conditions, these sensors run stably for 12 to 24 months. That compares to just 2 to 3 months for ordinary thermocouples. The extended life reduces replacement frequency and maintenance costs. It also eliminates production losses from frequent sensor changes.

Our purge type thermocouples come in two main series. The chemical ammonia synthesis type (WRPC) suits ammonia production, coal chemical plants, and sulfur recovery units. S and R indexing platinum-rhodium elements handle 0 to 1300°C. K-type elements cover 0 to 1100°C. The protection tube uses GH3039 nickel-based alloy or high-alumina ceramic material.

The metallurgical high-temperature type (WRST-□□□Q) serves blast furnaces, hot blast stoves, and heat treatment carburizing furnaces. Maximum temperature reaches 1300°C in reducing atmospheres. Both series can be equipped with ExdⅡCT6 flameproof junction boxes for hazardous area installation.

The purge type thermocouple junction box includes dedicated gas inlet and outlet ports on the side. An internal independent gas distribution chamber ensures the purge flow does not directly impact the sensing element. This preserves measurement accuracy. We recommend vertical installation to reduce the risk of liquid accumulation in the gas path.

Options include dual-element types (WRP2C-430) for redundancy and integrated 4-20mA transmitter types for direct DCS connection. Export shipments include ATEX, IECEx, and EAC explosion-proof certificates. We also provide English gas path structure test reports. Our technical team can advise on purge flow rate and pressure settings for your specific application.