Patent ID: 8251786

Claim:
A protection device for ventilation ducts where at least two directly vertically spaced apart duct openings for the supply of air or evacuation of air or both is provided, comprising: at least one protection slide comprising a sliding damper panel that is supported in a vertically displaceable manner and a sliding mechanism by means of which said protection slide is vertically driven from an open position to a closed position of a first one of said at least two directly vertically spaced apart duct openings, said first one of said at least two directly vertically spaced apart duct openings being completely covered by said protection slide in said closed position; and a compensating element for compensating the weight of said protection slide, a weight of said compensating element having substantially the same weight of said protection slide and said compensating element is constituted by another protection slide, capable of closing a second of the at last two directly vertically spaced apart duct openings wherein when the protection slide covers the first one of said at least two directly vertically spaced apart duct openings, the another protection slide covers the second one of said at least two directly vertically spaced apart duct openings.