Industrial RTD Assemblies —RTD-70 / RTD-80 / RTD-90 Series

Thermometrics RTD-70 through RTD-90 series are complete industrial Pt100 assemblies with a metal-sheathed probe, process connection, and weatherproof or explosion-proof connection head. The parallel of the TC-70 through TC-90 series for high-accuracy applications requiring RTD performance.

RTD-70 Fixed Process ConnectionRTD-71 Adjustable FittingRTD-80 Nipple-Union ExtensionRTD-90 Remote MountPt100 Class A StandardNEMA 4X / NEMA 7 Heads

Model Series

Industrial RTD Model Guide

Model	Name	Fitting	Extension	Head	Best For
RTD-70	Pt100 Industrial RTD — Fixed Head	Fixed ½" NPT	None	Aluminum Form B, NEMA 4X	General process; plant DCS; fixed installation
RTD-71	Pt100 Industrial RTD — Adjustable Fitting	Adjustable compression fitting	None	Aluminum Form B, NEMA 4X	Retrofit; variable insertion depth applications
RTD-80	Pt100 Industrial RTD — Nipple-Union Extension	Fixed NPT + nipple/union	2" to 12" nipple	Aluminum or cast iron	Insulated piping; head clearance over insulation
RTD-90	Pt100 Remote Mount RTD Assembly	Fixed NPT	Flexible conduit or armored cable	Remote-mount head	High-vibration areas; high ambient temperature

Technical Specifications

RTD-70 Series Data Sheet

Parameter	Specification
Sensing Element	Pt100 wire-wound or thin-film, IEC 60751
Accuracy Class	Class A standard (±0.15°C @ 0°C); Class AA or B available
Wire Config	3-wire standard; 4-wire available
Sheath OD	1/4" (6.4mm) standard; 3/16" and 3/8" available
Sheath Material	316SS standard; Inconel 600 for high-temp service
Process Connection	1/2" NPT standard; 3/4" NPT, BSP, flanged available
Insertion Length	2" to 24" standard; custom to 60"
Temperature Range	−200°C to 600°C (standard sheath); to 850°C on request
Connection Head	Aluminum Form B (NEMA 4X std); cast iron; SS; NEMA 7/9 XP
Transmitter Insert	DIN head-mount 4–20mA HART transmitter available

RTD vs. Thermocouple — When to Choose RTD

Temperature range<600°C: RTD preferred
Accuracy required±0.15°C or better: RTD only
Long-term stabilityRTD drifts less than TC
Lead resistance concernUse 4-wire RTD
Above 600°CThermocouple required
High vibrationThermocouple preferred

Transmitter Integration

Head-mount 4–20mA HART transmitters insert directly into the Form B connection head on RTD-70 and RTD-80 assemblies. The transmitter converts the Pt100 signal to a two-wire 4–20mA current loop, eliminating the need for a separate transmitter housing, conduit run, and power supply. Configured for sensor type, range, and fail-safe direction before shipment.