Stack Cap dampers are primarily used to isolate the stack opening and prevent foreign material from entering the stack when the stack is not in use, or to maintain the stack in a warm condition during maintenance or shutdown periods. A counterweight assembly is attached to the opposite end of the equipment to help distribute weight and minimize the actuator torque required for operation. Stack Cap dampers can be manually, electrically, or pneumatically operated.

The MDV damper is a single blade Diverter. Most commonly used in turbine exhaust applications, the MDV damper diverts the exhaust gas to either the bypass stack or allows it to pass through to a waste heat boiler. The sealing efficiency is better than 99.8% using the standard seal arrangement. For zero leakage a purge blower may be added.