Working Principle
The spring-loaded fixed thermocouple consists of a thermocouple probe mounted inside a protective sheath, backed by a compression spring. The spring mechanism pushes the sensing tip firmly against the bottom of a thermowell or a measurement surface, maintaining reliable contact pressure. This design minimizes air gaps and improves heat transfer, leading to faster response times and higher measurement accuracy.
Applications
Spring-loaded thermocouples are ideal for applications requiring:
- Stable and continuous contact with the measured surface
- Quick response to temperature changes
- High resistance to mechanical vibration
Typical industries and environments include:
- Petrochemical processing units
- Power generation facilities
- Chemical reactors
- Pipeline temperature monitoring
- Heat exchangers and boilers
- Heavy machinery with vibration or movement
Materials and Structure
- Sheath Material:
- 304 Stainless Steel (standard)
- 316 Stainless Steel (corrosion-resistant)
- Inconel 600 (high temperature, oxidation-resistant)
- Spring Material:
- Stainless Steel (durable, corrosion-resistant)
- Thermocouple Types Available:
- Type K (NiCr–NiSi)
- Type J (Fe–CuNi)
- Type T, E, N (optional)
- Insulation Type:
- Mineral Insulated (MI)
- Ceramic Insulation (for high temperature)
- Mounting Methods:
- Fixed threaded fittings (e.g., NPT, M20×1.5)
- Flanged connections
- Bayonet cap or custom mechanical fastening
Technical Specifications
| Parameter | Value |
|---|---|
| Temperature Range | -200°C to +800°C (depends on type) |
| Accuracy Class | Class I or II (IEC 60584-1) |
| Response Time | ≤ 3 seconds (in thermowell contact) |
| Spring Force | Typically 3–6N (customizable) |
| Protection Grade | IP65, IP67 (depending on housing) |
| Probe Diameter | Ø3mm to Ø8mm standard; others available |
| Length | Customizable probe length and insertion depth |
Key Advantages
- Ensures consistent contact and accurate readings
- Resists loosening due to vibration
- Reduces thermal lag compared to loosely mounted sensors
- Easy replacement and maintenance without removing the full assembly
- Highly customizable for different industrial needs