Ventilator pipe for use in multi-story building has flap which moves under spring control to open and close a transition zone

摘要

A main pipe (2) has a branch pipe (4) held in place on the main pipe (2) by a sliding flap (13). The flap (13) moves under spring (27) control to open and close a transition zone (6, 10). The flap opens when the temperature exceeds a pre-determined value.