Rosemount 644H Transmitter

Core Performance & Industrial Application

The Rosemount 644-1501-0001/AH is a 644H head-mounted temperature transmitter with integral RTD probe assembly, HART 4-20 mA, accepting RTD, thermocouple, mV and ohm sensors.

Standard accuracy ±0.15℃ (enhanced ±0.1℃ Pt100); Callendar-Van Dusen sensor matching; local LOI LCD; integral transient protection; SIL2/3 per IEC 61508.

Explosion-proof housing marked Ex d IIB T6; ambient -40℃ ≤ Ta ≤ +60℃; Inmetro/ATEX certification labels (NCC 12.1147X).

It converts process temperature to 4-20 mA/HART signal for DCS temperature loops.

Technical Specifications

▶ Product type: Head-mounted temperature transmitter + probe assembly

▶ Brand: Emerson Rosemount 644H

▶ Part: 644-1501-0001/AH; family 644 HART

▶ Input: RTD Pt100/Pt200, thermocouple, mV, Ω; single/dual sensor

▶ Accuracy: ±0.15℃ standard (±0.1℃ enhanced); 4-20 mA/HART rev. 5/7

▶ Supply: Loop powered 11-42 VDC; output 4-20 mA

▶ Certification: Ex d IIB T6; ambient -40~+60℃; SIL2/3; Inmetro/ATEX

▶ Feature: LOI LCD, sensor matching, transient protection

▶ Note: Sensor element type, probe length/immersion and process range confirmed from nameplate before ordering

▶ Country of origin: USA

▶ Compliance: CE, FM, ATEX, Inmetro certification

Industry Applications

Applied in process industry temperature measurement loops for refinery, chemical and utility temperature transmitter spare replacement.

Note: Confirm sensor type, immersion length and calibrated range against nameplate before ordering