Abstract: A system for blocking a plug valve, the system comprising: a plug (1) movable in rotation about an axis (Y-Y); and a blocker part (5); the system being characterized in that: the plug (1) presents an index portion having a first ramp (3) and a second ramp (4) that are arranged around the shaft (2) with oppositely-handed slopes; and the blocker part (5) presents first and second index portions (8, 9) adapted to come selectively into contact with the first and second ramps (3, 4) respectively; the first ramp (3) and the first index portion (8) serving to prevent the plug (1) from turning about the longitudinal axis (Y-Y) in a first direction of rotation, and the second ramp (4) and the second index portion (9) serving to prevent the plug (1) from turning about the longitudinal axis (Y-Y) in a second direction of rotation.

Abstract: The polygonal part (1) has, on each side (C1 to C6), at least one of the following assembly elements: at least one lug (3), at least one recess (4), each of said lugs (3) and each of said recesses (4) of the part (1) having a trapezoidal shape, with in each case complementary shapes, the trapezium of each of said lugs (3) widening towards the outside of the part (1) and the trapezium of each of said recesses (4) widening towards the inside of the part (1), and each of said lugs (3) having a width, defined transversely with respect to a right bisector of the corresponding trapezium, which is greater than the width of each of said recesses (4).

Abstract: A fluid transfer device including a rotor having two centrifugal wheels, and a stator incorporating a set of continuous axi symmetric return channels conveying the fluid from the first wheel to the second wheel. Each of the return channels includes in succession a diffusing portion that guides the fluid in a centrifugal direction, a bend portion that redirects the fluid stream in a centripetal direction, a return portion that guides the fluid along a centripetal path, and then an outlet portion formed in a first non-tubular part that guides the fluid towards the second wheel. In these channels, the diffusing portion and the bend portion are distinct parts, and the diffusing portion is formed in a second non-tubular part secured to the first non-tubular part. A method of fabricating the device.