Factory Original Emerson Rosemounts 644 Series 644 Rail Mount Temperature Transmitter 4-20 Ma

• Type: Network Type
• Measuring Medium: Temperature
• Display Type: LCD
• Accuracy: ±0.1% of Span (Rtd) / ±0.25°c
• IP Rating: IP67
• Certification: CE
• Customized: Customized
• Product Name: Emerson 644 Rail Mount Temperature Transmitter
• Measurement Type: Temperature (Rtd, Thermocouple)
• Input Types: PT100, PT1000, Ni120, Cu10, J, K, T, E, S, R, B, N
• Output Signal: 4–20 Ma (2-Wire), Hart® 7 Optional
• Warranty: 1 Year
• Power Supply: 12–30 V DC (Loop-Powered)
• Operating Temperature: -40°c to +85°c (-40°f to +185°f)
• Response Time: <1 Second (90% of Final Value)
• Electrical Isolation: 1500 V AC (Input to Output)
• Housing: Aluminum Alloy with Epoxy Coating
• Mounting: DIN Rail (En 50022) or Screw Mounting
• Process Connection: Terminal Block (Screw or Spring Clamp)
• Sensor Connection: 2/3/4-Wire Rtd or Thermocouple with Cold Junction
• Ambient Temperature: -40°c to +85°c (-40°f to +185°f)
• Vibration Resistance: 5 G RMS (10–150 Hz)
• Transport Package: Support Air/Land/Sea Transportation
• Specification: 40cm*30cm*30cm*
• Trademark: Rosemounte
• Origin: China
• HS Code: 9026201090
• Production Capacity: 100

Product Description

 

Product Parameters

 

Parameter	Specification
Measurement Type	Temperature (RTD, Thermocouple)
Input Types	Pt100, Pt1000, Ni120, Cu10, J, K, T, E, S, R, B, N
Output Signal	4–20 mA (2-wire), HART® 7 optional
Accuracy	±0.1% of span (RTD) / ±0.25°C (±0.45°F) for thermocouples
Power Supply	12–30 V DC (loop-powered)
Operating Temperature	-40°C to +85°C (-40°F to +185°F)
Response Time	<1 second (90% of final value)
Electrical Isolation	1500 V AC (input to output)

Product Description

644 Rail Mount Temperature Transmitter 4-20 mA - Product Description

The 644 Rail Mount Temperature Transmitter is a versatile and robust device designed for precise temperature measurement and signal conditioning in industrial automation systems. Engineered to convert inputs from RTDs, thermocouples, and other temperature sensors into a standardized 4-20 mA output signal, this transmitter ensures reliable performance in demanding environments such as oil and gas refineries, chemical plants, HVAC systems, and power generation facilities. Its DIN rail-mounted design, high accuracy, and compatibility with global safety standards make it a preferred choice for engineers seeking durability and ease of integration.

Core Technical Performance
The 644 Transmitter supports a wide range of temperature sensors, including Pt100, Pt1000, Ni120, Cu10 RTDs and J, K, T, E, S, R, B, N thermocouples, ensuring flexibility across applications. With an accuracy of ±0.1% of span for RTDs and ±0.25°C (±0.45°F) for thermocouples, it delivers precise data for critical processes. The 4-20 mA output (2-wire loop-powered) is compatible with most control systems, while the optional HART® 7 protocol enables digital communication for advanced configuration and diagnostics. Operating on a 12-30 V DC power supply, the device functions seamlessly in temperatures ranging from -40°C to +85°C (-40°F to +185°F) and responds to changes in under 1 second, ensuring real-time monitoring even in dynamic conditions.

Robust Design and Installation Flexibility
Housed in an IP66-rated aluminum alloy enclosure with epoxy coating, the 644 Transmitter resists dust, moisture, and corrosion, making it suitable for harsh outdoor or industrial environments. Its DIN rail mounting (compliant with EN 50022) allows quick and secure installation in control panels, while screw terminals or spring clamps simplify sensor wiring. The transmitter's 1500 V AC electrical isolation between input and output circuits protects against ground loops and electrical noise, ensuring signal integrity in electrically noisy settings.

Advanced Functional Capabilities
The transmitter features cold junction compensation (CJC) for thermocouple inputs, eliminating measurement errors caused by ambient temperature fluctuations. Its programmable rangeability allows users to scale the 4-20 mA output to match specific temperature spans, enhancing compatibility with existing control systems. For diagnostics and calibration, the optional HART® interface provides access to sensor health data, loop testing, and firmware updates. The device also supports SIL 2 certification (IEC 61508/61511), meeting functional safety requirements for critical applications.

Industry-Specific Applications
In oil and gas facilities, the 644 Transmitter monitors pipeline temperatures and tank farm safety systems, with ATEX/IECEx certification for Zone 2/22 hazardous areas. Chemical plants leverage its chemical-resistant housing and high accuracy to control reactor temperatures and distillation processes. For HVAC systems, the fast response time optimizes air handling unit (AHU) efficiency and chiller performance. In power generation, it withstands high vibrations to measure turbine inlet/outlet temperatures and cooling system integrity.

Certifications and Compliance
The transmitter complies with ATEX/IECEx II 3G Ex ic IIC T4 Gc for hazardous areas, DNV GL/ABS/LR marine standards for offshore use, and RoHS Directive 2015/863 for environmental safety. Its EN 61326-1 EMC immunity ensures reliable operation in electrically noisy environments, while MIL-STD-810G certification validates resistance to shock and vibration.

Competitive Advantages

Plug-and-Play Simplicity: Pre-configured for common sensors, reducing setup time.
Global Compatibility: Works with all major RTD and thermocouple standards worldwide.
Low Maintenance: Solid-state design with no moving parts ensures long-term reliability.
Scalability: Optional HART® 7 and LCD modules allow future upgrades without hardware replacement.
Optional Accessories
Enhance functionality with a HART® communication modem for digital diagnostics, a UV-resistant protective cover for outdoor installations, or an LCD display module for local temperature readouts. DIN rail mounting kits and custom calibration certificates are also available.
 

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Company Profile

KeRul (WeiFang) Automation Equipment Co., Ltd. is speciallzed in industrialautomation instrument development, production and sales, technical servicesand supporting equipment supply of specialized companies, The mainproducts are fow meters, level meters, temperature meters, pressuremeters, electrical meters, thermal meters, programmable controller(PLC), Dcs distributed control system, eight series of more than 1,000specifcations. its products and technologies are widely used in electrlcpower, metallurgy, petrochemical, environ. mental protection, plastics,food,l printing, tobacco, textile, dyeing and other fields.
 

 

 

 

Our Services

OEM / ODM services
To meet the user diversified requirement, Holykell have established a set of customer service and technical support system with OEM / ODM order as the center, and responded and Handle the customer's requirements in a timely manner to ensure accurate delivery time and product quality.

Order services
Fastest reply:Professional sales engineers 7/24 online services
Payment terms:T/T ,Western union, Paypal, Credit Card, L/C others
Fast delivery: within 24 hours release the cargo (normal spec.), Customized 7-12 days after payment .

MAINTENANCE & AFTER-SALES SERVICES
Customer Feedback:  Sales engineers and technical engineers will be one-on-one service for you to exclude all obstacles when use our sensors.

Warranty period: 12 months
Product life-long maintenance: Holykell can provide you with the maintenance of the whole life of the sensors

FAQ

Q: How long will you give me the reply?
A: We will reply to you as soon as we see the information
Q: What is the delivery time?
A:The products in stock will be shipped after receiving the payment, and the products that need to be ordered are subject to the factory time.
Q: How about your package?
A: Do not worry about the package, we have rich experience in packing.
Q: How about the payment terms?
A:You can choose T/T.
Q: What is the MOQ?
A:1PC.
Q: Can I get a lower price if I order large quantities?
A: Yes, cheaper prices with more bigger size orders.
Q:After sales and warranty?
A: We provide one year warranty lifetime technical support services.