The reason why thermocouples are widely used in industrial manufacturing lies in the fact that they strike the perfect balance between "wide measurement capabilities" and "solid reliability". Here are the significant advantages of thermocouples compared to other temperature sensors (such as thermistors, bimetallic thermometers, etc.):
1. Extremely wide temperature measurement range
This is the most indispensable advantage of thermocouples. They can cover an extremely wide range from close to absolute zero (through special models) to up to 2800°C (such as tungsten-rhenium thermocouples).
High-temperature adaptability: In high-temperature industrial scenarios such as metallurgy, heat treatment, and ceramic sintering, when other sensors (such as platinum resistors) are damaged by high temperatures or unable to measure, thermocouples are the only feasible contact-type temperature measurement option.
Low-temperature stability: Some models (such as T-type and E-type) still maintain good stability in low-temperature and cryogenic environments.
2. Durability and simplicity of structure
The thermocouple is made by welding two different metal wires together. The exterior is usually encapsulated by a metal sheath and mineral insulating materials (such as magnesium oxide).
Resistance to mechanical shock: Compared to glass thermometers or thermistors, armored thermocouples can withstand strong vibrations, shocks and high-pressure environments, and are highly suitable for installation in motors, pipelines or heavy machinery with intense vibrations.
Corrosion resistance: By choosing special shell materials (such as heat-resistant steel, Inconel alloy, etc.), thermocouples can work stably for a long time in acidic, alkaline or high-temperature oxidative atmospheres.
3. Fast response
The sensing end (hot end) of a thermocouple can be made very small (in a wire structure) and it is a direct contact type of temperature measurement, with an extremely low heat capacity.
For scenarios that require rapid detection of temperature changes (such as temperature control of injection machine nozzles, monitoring of exhaust temperature of internal combustion engines), thermocouples can provide response times of milliseconds, which are crucial for the real-time performance and safety of closed-loop control systems.
