Gas damper

A gas stream damper adapted to regulate the flow of a first gas stream and direct a second gas stream through the damper when the first gas stream is not flowing, comprising:

• a generally cylindrical housing having a first gas stream inlet at one end and a second gas stream inlet at the other end of the housing;
• a floating piston mounted within the housing having a cylindrical outer wall;
• a gas stream outlet in the housing spaced from said first inlet between said first and second inlets;
• and
• biasing means urging the piston toward said first inlet, said piston being selectively displaced by the buoyant force of the first gas stream flowing through the housing between said first inlet and said outlet to position it in partial covering relationship with respect to the outlet to vary the discharge rate of the first gas stream from the housing commensurate with the pressure in the gas stream downstream of the damper, and said biasing means being operative to position said piston between said first inlet and said outlet so that substantially the entire length of said cylindrical outer wall cooperates with the housing to close-off said first inlet while accommodating an essentially unobstructed flow of the second gas stream through the housing between said second inlet and said outlet when said first gas stream is not flowing.