A valve (1) comprises a housing (2) defining a flow path (5) between a first end (3) and a second end (4) of the housing (2). The valve further comprises a piston device (8) having a movable portion (9), which is movable between a closed position, in which liquid flow along the flow path is prevented, and an open position, in which liquid flow along the flow path is enabled. The movable portion (9) has a sealing portion (13) arranged to seal against an inside sealing surface (14) of the housing (2) in the closed position of the piston device (8). The piston device further has a spring portion (10) arranged to bias the movable portion (9) towards the closed position. The spring portion (10) forms an integral part of the piston device (8). The piston device (8) has a fixing portion (11), which is fixedly attached to said housing (2) and which defines part of the flow path (5). In the open position, liquid flow is enabled around the movable portion (9). A container (21) for a medical solution is also disclosed, as well as a tube set for use in a medical device. Further, a method of manufacturing a valve and a method of establishing a flow path between two liquid vessels are disclosed.
