Abstract: A locking device relating to a door construction to be used in an air raid shelter or the like. The door construction (1) comprises a door panel (4) arranged in a frame (3) and provided with a supporting frame (5). To make the door construction, subjected to a load, as unyielding and stable as possible, a mechanism (21 to 24) of the locking device (2) is arranged in the supporting frame (5), actual bolt members being constituted by cylinder elements (23) to be supported on the supporting frame (5) and to be arranged to comply in shape with recesses (31) of the frame (3).

Abstract: A closure device for shelters and the like. The frame (1) of the closure device is provided with at least one flow-through passage (2); a closure (3) is mounted displaceably in each passage; and a counter part is formed in the frame for each closure. The closure is displaceable between an open position, which permits a normal air flow, and a closed position, which may be caused by a pressure shock, in which the closure means is pressed against the counter part so as to close the respective passage. The objective is to provide a simple and steady structure, the operation of which is as efficient as possible. Accordingly, the passage (2) is defined by substantially U-shaped elements/partial elements (5a, 5b) which open towards each other in the direction of flow.

Abstract: A noise absorber for air or gas flows, which comprises a flow channel provided at opposite ends with flow inlet and outlet connections. One pair of opposite walls of the flow channel extends concavely and the other pair of opposite walls extends convexly from the inlet connection to the outlet connection. The flow channel is positioned in a surrounding box. Closed hollow spaces are formed between each wall of the flow channel and the opposite wall of the box, which spaces form compartments acting as resonator and/or absorption mufflers.