Structural Design
The simple probe-type thermocouple features a plain rod structure without additional mechanisms, with a smooth end on the protective tube, relying solely on physical insertion for contact between the measuring end and the object being measured.The spring-loaded thermocouple (also known as a compression spring type) integrates a built-in spring compression mechanism at the end of the protective tube, using elastic force to forcibly press the hot junction against the measured surface, creating constant contact pressure, significantly reducing contact thermal resistance and improving temperature measurement stability.
Installation Method and Operation Logic
The simple type uses pure insertion installation, requiring no tools or auxiliary devices. The operator can directly insert the probe into the temperature measurement hole, suitable for temporary, non-critical point rapid temperature measurement. The spring-loaded type requires manual pressing into a dedicated mounting base or fixture, using a spring clip for "one-click locking," eliminating the need for screwing or tightening flanges. It allows for repeated disassembly and assembly without drilling holes, and the installation process requires no tools, but the contact surface must be flat and free of oil stains.
Sealing and Applicable Environment
The simple type has no sealing capability, and is only suitable for atmospheric pressure, non-contact environments (such as air temperature measurement inside an oven). The spring-loaded type also does not have a media sealing function, and is specifically designed for surface temperature measurement, suitable for monitoring the surface temperature of solid objects such as injection molding machine molds, hot runner plates, metal plates, and heating rollers in food machinery. It is strictly prohibited for use in pipelines with fluids, high pressure, or corrosive media environments.
Temperature Measurement Performance and Accuracy
Due to unstable contact, the simple type is susceptible to vibration and oxidation layers, with a response time of approximately 5–8 seconds and lower accuracy. The spring-loaded type ensures close contact between the hot junction and the object being measured through constant spring pressure, shortening the thermal response time to 0.2–1 second, and controlling the temperature measurement error within ±0.5℃, significantly improving dynamic response and repeatability. It is the preferred solution for high-precision surface temperature acquisition.
Industry Positioning and Standard Classification
According to GB/T 16839-2018, both types belong to thermocouple packaging forms, but their installation methods are clearly classified: the simple type is classified as "without fixing device," while the spring-clip type belongs to the "pressure spring contact type" within the "with fixing device" category. Although it does not have a separate national standard number, its structure and function are widely recognized in industrial practice, and it is independently identified in product codes and technical documentation.
Typical Application Scenarios Comparison
Simple type: Temporary temperature measurement in laboratories, equipment maintenance and inspection, rapid verification of non-critical process points
Spring-clip type: Injection molding machine mold temperature monitoring, precise temperature control of hot runner plates, temperature measurement of heating rollers in food packaging machinery, surface temperature acquisition in metal rolling
Engineering Selection Principle: If rapid, non-destructive, and repeatable surface temperature measurement is required, and high response and high accuracy are demanded, the spring-clip type must be selected; if only temporary, rough, and non-contact temperature measurement is needed, the simple type is more economical. The functions of the two are not interchangeable, and incorrect mixing will lead to temperature drift, control inaccuracies, or process fluctuations.
