Schneider Electric (Barber Colman) MK-4621-422 Actuator

The Schneider Electric MK-4621-422 is a heavy-duty pneumatic valve actuator designed for precise proportional control in HVAC systems. Engineered with an 11 square inch effective area, this spring return actuator provides reliable linear movement for 1/2-inch nominal stroke applications. It operates on a specific 10 to 11.25 PSI nominal spring range, making it ideal for sequencing and precise throttling of steam or water valves. The rugged NEMA 1 enclosure protects the internal diaphragm and high-strength return spring from environmental debris, ensuring consistent performance in mechanical rooms. Featuring a standard 1/8-inch NPT air connection, the MK-4621-422 pneumatic actuator allows for seamless integration into existing Barber Colman or Schneider Electric control loops. Its durable construction is built to withstand the rigorous duty cycles of industrial and commercial pneumatic control systems without sacrificing accuracy or response time.

• Precise 10-11.25 PSI sequencing: Designed for exact calibration in multi-valve configurations.
• Fail-safe spring return: Ensures the valve moves to a predetermined safe position upon loss of control air.
• Direct-acting linear movement: Provides a consistent 1/2-inch stroke length for standard globe valve assemblies.
• Compact NEMA 1 footprint: Allows for installation in tight mechanical spaces while providing adequate physical protection.
• Interchangeable legacy design: Serves as a direct replacement for many older Barber Colman MK-4621 series units.

What is the maximum air pressure for the MK-4621-422?
The unit is typically rated for a maximum safe operating pressure of 30 PSI, though it is optimized for the 10 to 11.25 PSI control range.

Can this actuator be mounted in any orientation?
While versatile, it is standard practice to mount the actuator upright to prevent premature wear on the stem seals and to ensure optimal diaphragm life.

Does this unit include the mounting linkage?
This model number refers to the actuator assembly; specific valve linkages (such as the AV-400 series) may be required depending on your specific valve body configuration.

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.