Abstract: A fire flap arrangement for installation in a flow channel comprises a housing with opposite front walls and openings in the front walls. A pair of fire flaps are pivoted in said housing and held by means of permanent magnets in rest positions outside of the flow area. A locking bar within the housing can be displaced radially inwards pivoting the fire flaps into their locking positions in which they close the front wall openings. The locking bar in its locking position bridges the pair of fire flaps and presses them outwards against the front walls. The arrangement is actuated by a liquid pressure driven piston, the liquid also serving as a cooling medium for the housing.