Rosemount 644 Rail Mount Temperature Transmitter

Features and benefits

Fulfill your needs within one model family with a customizable transmitter design

■ Rail mount form factor

■ 4–20 mA/HART® Revision 7

■ IEC 61508 certified by an accredited third-party agency for use in safety instrumented systems up to SIL 3

■ Single or dual sensor inputs for RTD, T/C, mV, and ohm

■ Diagnostic suite

■ Transmitter-sensor matching with Callendar-Van Dusen constants

Standard transmitter design provides flexible and reliable performance in process environments

■ Offers improved measurement accuracy and reliability over direct-wiring a sensor to the digital control system for a lower overall installation cost

■ One-year stability rating reduces maintenance costs

■ Open/short sensor diagnostics assist with detecting issues in the sensor loop

■ Compensation for ambient temperatures enhances transmitter performance

Explore the benefits of a complete point solution from Rosemount Temperature Measurement

■ An “Assemble To Sensor” option enables Emerson to provide a complete point temperature solution, delivering an installation-ready transmitter, and sensor assembly.

■ Emerson offers a selection of RTDs, thermocouples, and thermowells that bring superior durability and Rosemount reliability to temperature sensing, complementing the Rosemount Transmitter portfolio.

Access information when you need it with asset tags Newly shipped devices include a unique QR code asset tag that enables you to access serialized information directly from the device. With this capability, you can:

■ Access device drawings, diagrams, technical documentation, and troubleshooting information in your MyEmerson account

■ Improve mean time to repair and maintain efficiency

■ Ensure confidence that you have located the correct device

■ Eliminate the time-consuming process of locating and transcribing nameplates to view asset information

Specifications 

Environmental conditions

Ambient operating temperature range Standard: -50 to +85 °C  SIL: -40 to +80 °C

Storage temperature :-50 to +85 °C

Calibration temperature; 23...25 °C

Humidity: < 99% RH (non-cond.)

Protection degree: IP20

Mechanical specifications 

Dimensions: (H x W x D) 109 x 23.5 x 104 mm

Weight, single input / dual input: 150 g/160 g

Maximum wire size :0.13...2.08 mm2 /AWG 26...14

stranded wire Screw terminal torque :0.5 Nm

Vibration: IEC 60068-2-6 : 2...25 Hz: ±1.6 mm /25..100 Hz: ±4 g

Common specifications

Supply voltage, DC : 

Rosemount 644R Ordinary Location: 7.5(1)...48(2)VDC

Rosemount 644R Hazardous Approval: 7.5(1)...30(2)VDC

Additional minimum supply voltage when using test terminals :0.8 V
Maximum internal power dissipation :≤ 850 mW per channel

Minimum load resistance at > 37 V supply: (Supply voltage – 37)/23 mA

Isolation voltage, test/operation: 

Rosemount 644R Ordinary Location: 2.5 kVAC/55 VAC

Rosemount 644R Hazardous Approval: 2.5 kVAC/42 VAC

Polarity protection: All inputs and outputs

Write protection: Jumper or software

Warm-up time :< 5 minutes

Start-up time: < 2.75 seconds

Programming :HART® protocol

Signal/noise ratio :> 60 dB

Long-term stability, better than: 

±0.05% of span/year / ±0.18% of span/5 years

Response time :70 ms

Programmable damping :0...60 s

Signal dynamics, input :24 bit

Signal dynamics, output :18 bit

Effect of supply voltage variation: < 0.005% of span/VDC

Packaging & Shipping

Packaging: Original bag and box