SITRANS TF320/TF420

SITRANS TF320/TF420 field-mount temperature transmitters with SIL2/3, dual sensor inputs, high accuracy and diagnostics for demanding industrial environments.

Head-mounted temperature transmitters for reliable measurement, easy integration, and advanced diagnostics, from standard to high-availability applications.

Rail-mounted temperature transmitters for accurate measurement, easy panel integration, and smart diagnostics—from standard loops to high-availability applications.

The SITRANS TS500’s modular design makes it exceptionally versatile, delivering precise temperature measurements even in harsh industrial environments.

SITRANS TF320 and TF420 combine flexible sensor connectivity, robust field housing and simple local or remote configuration. Both are available in single- or dual-chamber aluminum or stainless-steel versions. TF320 covers standard measurement points with one universal input. TF420 adds two separately configurable inputs with hot backup for higher availability.

Hot backup in SITRANS TF420 automatically switches to a second sensor if the primary fails, helping keep critical processes running and reducing unplanned downtime.

SIL 2/3 certification and broad Ex approvals make transmitters suitable for safety‑critical applications and extreme environments down to −50 °C. Optional internal surge protection up to 6kV (dual chamber enclosure).

With support for RTDs, thermocouples, resistance and mV signals, one transmitter family can be used across a wide range of temperature applications.

Resistance thermometers, thermocouples, resistors, potentiometers, DC voltage sources

4…20mA (SITRANS TF320), HART 7 (SITRANS TF320/420), Profibus PA (SITRANS TF420)

Aluminum; stainless steel CF3M/1.4409 similar to 316L (dual chamber enclosure); stainless steel 1.4401 similar 316 (single chamber enclosure)

ATEX, IECEx, FM (US/CA), EACEx, NEPSI, KCs, Inmetro, PESO, ECASEx. Protections: Intrinsic safety, increased safety for Zone 2, flameproofed, dust ignition proofed; SIL 2/3; electrical equipment for furnace and ancillary equipment (EN50156-2); marine EURO and DNV

Hardware and software write protection for maximum security against unauthorized access; uninterruptible loop current measurement for tests; screw terminal wire cross section up to 2.5mm²; internal surge protection up to 6kV (optional)

Top input accuracy for Pt100 (IEC60751) +/- 0.04 °C; Stability: +/-0.05 °C (1 year) or +/-0.18 °C (5 years); 2x 4-wire RTD connection (TF420)

Remote Safety Handling supports remote configuration, maintenance and SIL validation from the control room, reducing exposure in hazardous areas and shortening commissioning. It helps reduce service effort, while remote access to status, diagnostics and measurement data simplifies operation and minimizes the need for time-consuming field visits.

Extensive diagnostics according to NAMUR NE107 provide clear, standardized status information for device and sensor conditions, helping operators assess measurement quality at a glance. Functions such as sensor interruption, short-circuit and drift detection make deviations visible early, support condition-based maintenance and enable more targeted service planning with less troubleshooting effort in the field.

A clear, user-friendly display supports fast status reading directly at the measuring point and can be rotated in 90° steps for better visibility in different mounting positions. In the dual-chamber enclosure, optional, large external push buttons enable convenient local operation and quick access to key settings. In the single-chamber enclosure, key parameters can also be operated directly via the display.

Callendar-van-Dusen-based sensor trim improves accuracy and shortens calibration time. With ambient temperatures down to –50°C and SIL 2/3 certification for HART variants, it is suited to harsh and safety-related applications. An on-board alarm backup helps ensure reliable device error indication also for high-current setting 21mA.

The main difference is the number of inputs. TF320 has one configurable universal input, while TF420 has two separately configurable inputs and supports hot backup for higher availability.

They support universal inputs such as RTDs, thermocouples, resistance and mV signals, enabling use across many temperature measurement tasks.

Depending on the version, configuration is possible via PC, SIMATIC PDM, HART communicator, PROFIBUS PA or optional local operation on the device, via display (single chamber enclosure) or control keys accessible from outside (dual chamber enclosure).

Selected versions support SIL 2/3 applications and can be integrated into Remote Safety Handling concepts for remote monitoring, diagnostics and safety-related maintenance tasks. Further, they can operate as safety devices in furnace applications according to EN 50156-2.

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