Thermometrics manufactures RTD assemblies across the full IEC 60751 accuracy spectrum. Wire-wound and thin-film sensing elements, 2-/3-/4-wire configurations, and custom sheath materials for process, laboratory, and aerospace applications.
| Parameter | Specification |
|---|---|
| Element Type | Wire-wound (ceramic / glass) · Thin-film chip |
| Nominal Resistance | Pt100 (100 Ω at 0°C) · Pt1000 (1000 Ω at 0°C) |
| Temperature Coefficient | α = 0.00385 Ω/Ω/°C (IEC 60751 / DIN 43760) |
| Accuracy Classes | Class AA (±0.1°C @ 0°C) · Class A (±0.15°C) · Class B (±0.3°C) · 1/3 DIN (±0.1°C) |
| Operating Range | −200°C to 850°C (element-dependent) |
| Wire Configurations | 2-wire · 3-wire · 4-wire (Kelvin) |
| Sheath OD | 1/16" to 1" (custom on request) |
| Sheath Materials | 316 SS · 304 SS · Inconel 600 · Inconel 625 · Titanium · Hastelloy C276 |
| Insulation | MgO · Ceramic · PTFE · Fiberglass |
| Process Connections | NPT threaded · Tri-clamp · Flanged · Compression fitting |
| Self-Heating Error | <0.1°C typical at 1 mA excitation |
| Response Time (t63) | 0.5–8 sec (sheath-diameter-dependent) |
| Calibration Standard | NIST-traceable · IEC 60751 |
4-wire (Kelvin) configurations eliminate lead resistance error entirely, making them the preferred choice for laboratory and metrology applications where measurement uncertainty must be minimized. Thermometrics supplies 4-wire assemblies with matched extension leads.
Direct-immersion probe for liquid and gas process streams. Straight or tapered immersion length to customer specification. Available with spring-loaded retraction, adjustable compression fittings, or fixed process connections.
Flat-bottom weld-pad RTDs for tube-skin or pipe-surface measurement. Welded directly to OD surface. Low thermal mass enables fast response to surface temperature changes in heat exchangers and process piping.
3-A and FDA-compliant assemblies for hygienic process applications. Electropolished wetted surfaces, no crevices, tri-clamp or hygienic thread connections. Full material traceability and surface roughness documentation available.
RTD element sized to fit standard thermowell bore. Spring-loaded tip ensures consistent thermal contact with the thermowell closed end. Separable design allows element replacement without process shutdown.
RTDs offer fundamental advantages over thermocouples in accuracy, stability, and linearity — making them the preferred sensor for precision process control, calibration, and laboratory measurement.
IEC 60751 Class A elements achieve ±0.15°C at 0°C. Class AA achieves ±0.1°C. RTDs exhibit excellent long-term drift stability, typically <0.1°C/year in stable environments.
RTD resistance-temperature relationship is highly predictable and described by the Callendar-Van Dusen equation, simplifying transmitter linearization and eliminating the need for thermocouple cold-junction compensation.
Unlike thermocouples, RTDs do not require a cold-junction compensation circuit. Two-wire, three-wire, and four-wire configurations allow trade-offs between lead resistance compensation and installation complexity.
Sheath materials available in 316SS, Inconel 600/625, Hastelloy C276, titanium, and tantalum for aggressive process chemistries. PTFE and ceramic insulation for high-purity and high-temperature applications.
All Thermometrics RTD assemblies are calibrated against NIST-traceable reference standards. Individual calibration certificates with measured R vs. T data are available on request.
Extension leads cut to length, terminated with Amphenol connectors, terminal blocks, or flying leads. Silicone, PTFE, and fibreglass jacket options. Matched resistance extension wire available.
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