Nonreturn device for a pipe for carrying a fluid

A nonreturn device (1) for a fluid-carrying pipe (2), said nonreturn device (1) includes, positioned on said pipe (2):

• a shut-off gate (3) of the two-position type, an active one for shutting said pipe (2), and an inactive one, provided with a mobile selector element associated with actuation means (5),
• a nonreturn valve (6) including an inlet (6a) and an outlet (6b), taking into account the normal direction of displacement of the fluid, adapted to maintain a fluid pressure difference ΔP between said inlet (6a) and said outlet (6b), and
• a triggering piston (8) comprising a body (81) delimiting an internal volume (82) separated into two chambers (82a, 82b) by a mobile element (83) that is equipped with an activation rod (84),
• a first one of said chambers (82a) being in fluidic communication with said pipe (2) downstream from said nonreturn valve (6), and
• a second one of said chambers (82b) being in fluidic communication with said pipe (2) upstream from said nonreturn valve (6),
• wherein said actuation means (5) of said shut-off gate (3) are provided with a device for accumulating/releasing potential energy (54, 54′), adapted to accumulate potential energy when said shut-off gate (3) passes from its active position to its inactive position, and adapted to release said potential energy when said shut-off gate (3) passes from its inactive position to its active position,
• said activation rod (84) of said triggering piston (8) being adapted to be able to actuate said actuation means (5) of the selector element of said shut-off gate (3), in order to operate the latter from its inactive position to its active position, in the case where said pressure difference ΔP passes under a predetermined threshold, with release of the potential energy accumulated by said device for accumulating/releasing potential energy (54, 54),
• wherein the actuation means (5) of the mobile selector element of said shut-off gate (3), include an operating arm (51) associated with a mobile actuation trigger (52),
• wherein said trigger (52) includes a seat (53) adapted to bear against a retractable stop (85) carried by said actuation rod (84) of said triggering piston (8), under the effect of said device for accumulating/releasing potential energy (54),
• wherein said actuation trigger (52) is then adapted to occupy two positions:
• a locked one, in which said seat (53) bears against said retractable stop (85), said shut-off gate (3) being in inactive position through the operating arm (51), and
• an unlocked one, in which, after retraction of said retractable stop (85), said seat (53) does not bear against said stop (85), and in which said shut-off gate (3) is in active position, through the operating arm (51).