Abstract: The safety valve for fluids subject of this Patent is a spherical valve for a straight or right-angle (90°) flow and a quarter-turn. Its structure comprises: a box (1) having a small central cylindrical recess (2) on its bottom, and two diametrically opposed notches (6) in its neck (5). A spherical body (4) provided with two throats (8) on its driving shaft (7) and a central cylindrical projection (3) on the bottom end of the axis of longitudinal symmetry. An intermediate tube-shaped part (10) between the shaft (7) of the body (4) and the neck (5) on the box (1), provided with two peripheral throats (11). A washer (13) provided with two diametrically opposed radial projections (14). A manual control (15) provided with two diametrically opposed dissymmetrical projections (16)-(17). The sealing means are: two O-ring seals (9) on the driving shaft (7) and a further two (12) on the intermediate part. Two annular elastic seals (18) between the box (1) passages and the spherical body (4).