Barber Colman (Schneider Electric) MK-8821 pneumatic valve actuator is a proportional control actuator engineered for smooth linear valve movement in HVAC and building automation systems.
 
This spring return model operates on an 8–13 psi pneumatic control signal to provide stable modulating valve control, while the return spring helps move the assembly to its normal position if control air is lost.
 
Designed for indoor NEMA 1 application, the MK-8821 is suited for pneumatic control air systems that require accurate stroke response, repeatable positioning, and dependable valve actuation.  Its 100 sq. in. actuator area, 1/8 in. NPT air connection, and 1 in. nominal stroke support reliable operation in compatible hydronic and air-handling control assemblies.
 
Ideal for replacement and retrofit service, this actuator helps restore precise control performance in legacy Barber Colman and Schneider Electric pneumatic valve systems.