10 means are shown for blocking the valve in the open position indeed during a long period of non use in particular during storage it is preferable for flexible section 1 not to be torsionally stressed to avoid its elastic properties deteriorating in particular sticking if the flexible section is in silicone in the example shown the blocking means include a pin 27 that can form a retaining stop for gripping means 14 in the position shown on fig4 flexible section 1 is open whereas torsion spring 24 is tensioned it will be noted that the blocking means of the invention can be used with various types of rotational actuating means involving a cable or a gear system according to the example shown and advantageously gripping means that can operate the actuating means have a displacement which is appreciably in longitudinal direction 30 of the valve so as to maximize the ergonomy of the assembly a system for transforming the movement is thus provided between gripping means 14 and end 3 which is mobile in rotation in the example shown the system for transforming the movement includes pulley 12 and the cable actuating rotary shaft 9 the transformation of movement can be produced by other actuating means according to the embodiment more precisely shown in fig1 to 15 a second cable 32 is created so as to transmit an opposite movement to the movement produced by.