lower edge with a fuse link cable 66 extending from the hook 65 to another hook 68 on the inner surface of the front wall 22 normally the cable 66 will maintain the damper in the vertical open position as shown in full however in the event of a fire the fuse link attached cable 66 will disintegrate when exposed to a predetermined temperature level thereby releasing the damper for pivotal movement into the closed position in practice when the exhaust fan is turned on a main control valve not shown is opened to release cold water for downward movement along the wall 26 into the scrubbing chamber area as defined the exhaust air stream is drawn initially in a downward direction through the inlet passage 14 then is caused to undergo a reversal in flow around the lower edge of the panel 24 and advance upwardly through the scrubbing chamber as the air flow turns upwardly and advances past the the downward flow of water and draw the water upwardly to a level adjacent to lip 53 where the air velocity decreases and allows the water to fall in a somewhat circular path toward walls 22 and 26 as the water continues to move downwardly along the lower wall 26 in countercurrent relation to the flow of air it will once again be picked up by the flow of air thereby creating a vortex action with the water in continuous suspension.