Schneider Electric (Barber Colman) MK-4801 Valve Actuator

The Schneider Electric MK-4801 represents a rugged solution for proportional control within high-capacity HVAC systems. This pneumatic valve actuator features a factory-calibrated 3 to 8 psi spring range, designed to provide consistent force for modulating 1-1/2" to 2" VB-9XXX series valve bodies. Built with a metal NEMA Type 1 enclosure, the MK-4801 handles a 30 psig maximum air pressure, ensuring reliable operation in demanding mechanical rooms. The internal spring return mechanism is engineered for fail-safe performance; on a loss of pneumatic signal, the spring retracts the actuator shaft and raises the valve stem to a predetermined safe position. Field installation is streamlined via the 1/8" NPT air connection and universal mounting bracket, making it a drop-in Barber Colman replacement actuator for retrofits or new construction. Its high-torque output provides the necessary close-off pressure for chilled water, hot water, and steam applications requiring precision pneumatic flow control.

• Fail-Safe Operation: Mechanical spring return ensures the valve stem raises upon loss of air pressure to prevent system overheating or flooding.
• Durable Construction: The NEMA Type 1 aluminum housing protects internal diaphragms from environmental debris and mechanical impact.
• Valve Compatibility: Specifically engineered for seamless integration with Schneider Electric VB-9213, VB-9313, and VB-9223 valve bodies.
• High Pressure Tolerance: Rated for up with 30 psig air supply, allowing for integration with standard and high-pressure pneumatic control loops.

What is the effective diaphragm area of the MK-4801?
The unit features an 11 square inch effective area, providing the necessary force to overcome high differential pressures in 2-inch valve applications.

Can the MK-4801 be used for both water and steam valves?
Yes, as long as it is paired with the compatible VB-9XXX series globe valves, it is suitable for modulating both water and low-pressure steam media.

What air connection size is required for installation?
The actuator utilizes a standard 1/8" NPT female pipe thread, compatible with typical pneumatic tubing and barbed fittings.

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.