Abstract: A gate-valve comprising a gate-valve body inside of which a gate-valve seat is formed having a stop surface delimiting the orifice of a pipe, a valve moving in a linear direction in the gate-valve body, the valve having an upper shoulder and a lower shoulder axially distanced from the upper shoulder, and a seal fitted between the two shoulders intended to stop the orifice of the pipe, the pipe having an internal peripheral surface which is parallel with the direction of displacement of the valve, characterized in that the valve comprises a limiting means to limit the flow of a liquid between a surface of the valve and the internal peripheral surface of the pipe during the displacement of the valve while the seal is not completely removed from the orifice of the pipe.

Abstract: The invention concerns a drainage unit in particular for aircraft sanitation systems.The technical problem resides in providing such a unit which is extremely simple, reliable and effective.According to the invention, this unit, which is formed by a mobile truck (1) carrying a collecting reservoir (12), comprises depression-producing means (18, 19) connected to the collecting reservoir (12) so as to produce the vacuum therein and take-off means (14) mounted in a support (15) and capable of being temporarily connected to the sanitation systems of the aircraft for transferring waste materials and waters to the reservoir (12), the depression-producing means (18, 19) for the reservoir, the take-off means (14) and the reservoir (12) being disposed on the chassis (4) of the truck (1) in the form of a compact assembly inscribed within the frame of the chassis (4).The invention is principally employed for the rapid draining of aircraft sanitation systems.