Barber Colman 4821 Actuator

The Barber Colman MK-4821 is a pneumatic valve actuator designed for precise modulating control of 1½” to 2″ VB-9xxx series valves in HVAC and industrial systems. Featuring an 11 in² diaphragm and operating within an 8 to 13 psig spring range, it ensures reliable valve positioning in response to pneumatic control signals.​

Technical Specifications

  • Model: MK-4821

  • Type: Pneumatic valve actuator

  • Diaphragm Area: 11 in² (71 cm²)

  • Spring Range: 8 to 13 psig

  • Maximum Air Pressure: 30 psig

  • Control Signal: Proportional

  • Spring Return: Yes; retracts actuator shaft and raises valve stem upon air pressure loss

  • Enclosure Rating: NEMA Type 1

  • Compatible Valves: 1½” to 2″ VB-9xxx series

  • Condition: New​

Key Features

  • Provides precise modulating control for compatible valves

  • Spring return mechanism ensures fail-safe operation during air pressure loss

  • Compact design suitable for various installations

  • Designed for 8 to 13 psig control signals

Compatible Applications

  • HVAC systems requiring modulating valve control

  • Industrial processes involving fluid regulation

  • Systems utilizing VB-9xxx series valves

Installation & Maintenance Notes

  • Ensure proper alignment when mounting to compatible valves

  • Verify pneumatic connections are secure and leak-free

  • Regularly inspect actuator for signs of wear or damage

  • Follow manufacturer guidelines for maintenance procedures


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