Abstract: This invention is concerned with a stop valve of the type mounted along a fluid carrying pipe, which comprises a closing valve plate hinged about one fixed pin mounted on one internal side of a pipe and operating means for opening and closing the valve plate in the pipe. In accordance with the invention, the operating means consist in at least two articulated links forming an angle lower than 180.degree. therebetween, one of the extremities of said two links being mounted on the valve plate, the other extremity being mounted on the internal side of the pipe opposite to the side where is mounted the hinging pin of the closing valve, and control means extending from said internal side opposite to the side where the hinging pin is mounted to the articulation of the two links, for moving the latter and thus opening or closing the angle formed between the two links.