Exhaust system for smokestack

摘要

A smokestack for boilers or the like has an exhaust control system on the top opening of the smokestack to change the size of the orifice through which the gaseous exhaust exits. Structure is provided for automatically adjusting the size of the orifice in response to changing pressure conditions within the smokestack to maintain the orifice at an optimum size for the conditions prevailing at a given time.