An adapter (100, 200) for attaching a control device (140, 240) to a valve arrangement (120, 220). The adapter (100, 200) is configured to engage with the valve arrangement (120, 220) via a snap-fit connection, and to engage with the control device (140, 240) via a threaded connection. The snap-fit connection is formed by a first
interlocking part (203a, 203b) provided on an inside (202) of the adapter (100, 200) engaging a second
interlocking part (222a, 222b) of the valve arrangement (120, 220) such that the adapter (100, 200) is retained to the valve arrangement (120, 220). The first
interlocking part (203a, 203b) is movable in a resilient manner in a radial direction (R) such that, when the adapter (100, 200) becomes engaged with the valve arrangement (120, 220), the first interlocking part (203a, 203b) expands in the radial direction (R) and thereafter snaps back in the radial direction (R) to form the snap-fit connection. The adapter (100, 200) is provided with male threads (211) arranged circumferentially with respect to the axial direction (A). The threaded connection is formed by the male threads (211) engaging female threads (241) of the control device (140, 240) such that the adapter (100, 200) is retained to the control device (140, 240). The male threads (211) are tapered towards the second axial end portion (210) of the adapter (200) to enable the first interlocking part (203a, 203b) to become pressed inwards in the radial direction (R) when the adapter (200) becomes engaged with the control device (240) via the threaded connection and thereby preventing the first interlocking part (203a, 203b) from expanding in the radial direction (R) when the adapter (100, 200) is engaged with the control device (140, 240) via the threaded connection.