Adjustable constant air volume dampers Constant air volume dampers which facilitates balancing of ventilation systems. Those dampers maintain the constant air volume at varying pressures, caused by connection and disconnection of system parts, clogging of filters and ducts, wind effects, window opening etc. SKC is an automatic damper independent of external energy sources. The damper is operated by an opposed opening force from a spring on the blade. Housing and damper blade are constructed from galvanized steel and tightness joint from rubber.