Importance

Loading Importance Indicators...

Abstract

A draft limiting device for controlling the draft in a flue gas passage, includes a flap which is supported on a swing shaft in a secondary air inlet for swiveling movement between a closed position, at which the flap extends in a substantially vertical plane to block entry of air from a room into the secondary air inlet, and a fully open position at which the flap is displaced a certain angle about the axis of the swing shaft to admit air through the air inlet to the flue gas passage. A solid, semi-cylindrical member is fixed to the flap so that the center of radius of the member is parallel to the swing shaft axis, and the member extends on diametrically opposite sides of the swing shaft axis. The member thereby provides a restoring moment to the flap as the flap is moved in response to a differential pressure from the closed to the open position. The magnitude of the restoring moment is either constant or decreases as the flap moves in the direction from the closed to the open position. This arrangement serves to maintain the draft in the flue gas passage at a desired value.

Loading the Abstract Image...

First Claim