The invention relates to a non-return valve with a valve sleeve, comprising a valve seat and a flow opening and a sealing body moveable in the valve sleeve, comprising a bulged sealing face, wherein the bulged sealing face is arranged at a head end of the sealing body and the non-return valve comprises guiding means for the axial guidance of the sealing body in the valve sleeve, so that the sealing face always faces the valve seat, and a locking element is inserted into the valve sleeve through the flow opening and is fixed therein, so that the locking element restricts the movement of the sealing body in the valve sleeve.

Described is a check valve having a valve housing, a valve seat, a ball and a spherical loading element. The valve seat is disposed proximate to a first end of the bore. The ball is disposed in the bore and is movable between a closed position in which the ball is received against the valve seat and prevents a flow of fluid through the bore and an open position in which the ball is displaced from the valve seat and allows fluid to flow through the bore. The spherical loading element is disposed in the bore and is movable between the ball and the second end of the bore. The spherical loading element applies a supplemental force to move the ball against the valve seat during closing of the check valve. The check valve provides a low and predictable cracking pressure which does not vary significantly between similarly manufactured valves.