Belimo B278+AFRX24-MFT-S Valve Assembly

The Belimo B278+AFRX24-MFT-S is a high-performance 2-way characterized control valve assembly engineered for demanding HVAC applications requiring precise hydronic regulation. Featuring a 3-inch NPT internal thread connection and a high 130 Cv rating, this assembly utilizes a stainless steel ball and stem to ensure long-term reliability and resistance against scaling or corrosion. The characterized control valve (CCV) design incorporates a specialized Tefzel characterizing disc, providing an equal percentage flow characteristic that eliminates control loop hunting and maintains stability in variable flow systems, such as air handling unit coils and large-scale bypass loops.

Actuation is provided by the AFRX24-MFT-S spring return actuator, delivering 180 in-lb of torque to ensure positive close-off up to 100 psi. This Multi-Function Technology (MFT) actuator is fully programmable, supporting 4-20mA (via 500 Ohm resistor), PWM (1500 Ohm), floating point, and On/Off signals at 24Vac/Vdc. For enhanced system integration, the unit includes two built-in auxiliary switches (SPDT) for end-position verification or interlocking control. With a rugged NEMA 2/IP54 housing and a failsafe mechanism that drives the valve to its original position during power loss, this assembly is a standard for professional contractors prioritizing system uptime and linear control response.

Key Benefits

• Equal Percentage Flow: Specialized disc design provides superior linear thermal response and prevents rapid cycling.
• High Close-Off Reliability: 180 in-lb spring return ensures 0% leakage (A-AB) even under significant differential pressure.
• Stainless Steel Trim: High-grade stainless steel ball and stem offer maximum durability in chilled or hot water systems up to 60% glycol.
• Flexible Control Logic: Programmable MFT interface allows for modulating control or multi-signal input without hardware changes.
• Position Feedback: Integrated auxiliary switches provide remote status confirmation for Building Automation Systems (BAS).

Common Questions

What is the maximum fluid temperature for this assembly?
The B278 valve body is rated for media temperatures ranging from 0°F to 212°F (-18°C to 100°C).

How do I configure the actuator for a 4-20mA control signal?
Modulation via 4-20mA requires the installation of a 500 Ohm resistor to convert the current signal to the standard 2-10VDC operating range.

Can the fail-safe direction be reversed?
Yes, the spring return direction (clockwise or counter-clockwise) is reversible by simply flipping the actuator mounting orientation on the valve stem.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.