A compressor unit check valve assembly or a vacuum pump check valve assembly configured to be mounted at the interface between the compressor unit or the vacuum pump and an external network , for preventing a fluid flow in the upstream direction, the check valve assembly comprising: - a valve body adapted to receive a valve plate , said valve plate being adapted to pivot between a first open position in which fluid can flow through said check valve and a second closed position in which fluid cannot flow through said check valve ; - said valve body being adapted to be connected to a discharge port of a compressor unit or to the intake port of a vacuum pump through a first fluid conduit , whereby the first fluid conduit is provided with a flange (F) determining a vertical plane (FF) at an end of the flange (F) opposite to the first fluid conduit , onto which plane (FF) the valve body is connected; - a second fluid conduit attachable to the valve body , said second fluid conduit being adapted to be connected to an external network ; - a shaft and at least one bearing for connecting the valve plate to the valve body ; whereby the valve plate comprises an elongated area having a hollow tube through which the shaft is inserted for rotatably mounting said valve plate in the valve body characterized in that said at least one bearing is positioned on said shaft and within said hollow tube; in that said valve body further comprises a seat for receiving said valve plate , said seat having, with respect to a direction perpendicular to the vertical plane (FF) and inverse to the upstream direction, a lower part (H1), in the vicinity where said elongated area is mounted, and a higher part (H2), on the opposite side from where said elongated area is mounted, such that the valve plate is received on said seat under an angle (α) with respect to the vertical plane (FF), said angle (α) being created due to the difference between the higher part (H2), and the lower part (H1); in that the valve plate is adapted to be mounted eccentrically in the valve body , such that the check valve can open further than when the check valve would not be mounted eccentrically in the valve body ; and in that - in case of the compressor unit , the second fluid conduit creates a space in which the valve plate pivots freely between the first open position and the second closed position; and - in case of the vacuum pump , the first fluid conduit creates a space in which the valve plate pivots freely between the first open position and the second closed position. - a valve body adapted to receive a valve plate , said valve plate being adapted to pivot between a first open position in which fluid can flow through said check valve and a second closed position in which fluid cannot flow through said check valve ; - said valve body being adapted to be connected to a discharge port of a compressor unit or to the intake port of a vacuum pump through a first fluid conduit , whereby the first fluid conduit is provided with a flange (F) determining a vertical plane (FF) at an end of the flange (F) opposite to the first fluid conduit , onto which plane (FF) the valve body is connected; - a second fluid conduit attachable to the valve body , said second fluid conduit being adapted to be connected to an external network ; - a shaft and at least one bearing for connecting the valve plate to the valve body ; - in case of the compressor unit , the second fluid conduit creates a space in which the valve plate pivots freely between the first open position and the second closed position; and - in case of the vacuum pump , the first fluid conduit creates a space in which the valve plate pivots freely between the first open position and the second closed position. <EOS>