Apparatus for transferring a liquid between a storage container and at least one further use container, - having a storage-container sealing portion for leaktight abutment of a main body of the transfer apparatus against the storage container, - having a hollow-needle assembly with a hollow needle, wherein the hollow-needle assembly is displaceable in a linear manner along a movement axis relative to the main body between -- a retracted rest position and -- an extended connecting position in which the hollow needle creates a liquid connecting duct between the storage container and the transfer apparatus, - having a connecting portion for connecting the transfer apparatus to the use container in a leaktight manner, - having a pressure-actuation element via which the hollow-needle assembly between the rest position and the connecting position is displaceable and which is rigidly connected to the hollow needle during displacement, - having a guide device for axial guidance of the pressure-actuation element on the main body during the displacement of the hollow-needle assembly from the rest position into the connection position, wherein the guide device has at least one guide pin which slides in at least one associated guide groove during the displacement from the rest position into the connection position, - wherein the guide device is configured such that the displacement of the hollow-needle assembly from the rest position into the connecting position is irreversible, characterized in that the guide groove is continued by a helical guide which makes it possible to unscrew the pressure-actuation element from the main body. - having a storage-container sealing portion for leaktight abutment of a main body of the transfer apparatus against the storage container, - having a hollow-needle assembly with a hollow needle, wherein the hollow-needle assembly is displaceable in a linear manner along a movement axis relative to the main body between -- a retracted rest position and -- an extended connecting position in which the hollow needle creates a liquid connecting duct between the storage container and the transfer apparatus, -- a retracted rest position and -- an extended connecting position in which the hollow needle creates a liquid connecting duct between the storage container and the transfer apparatus, - having a connecting portion for connecting the transfer apparatus to the use container in a leaktight manner, - having a pressure-actuation element via which the hollow-needle assembly between the rest position and the connecting position is displaceable and which is rigidly connected to the hollow needle during displacement, - having a guide device for axial guidance of the pressure-actuation element on the main body during the displacement of the hollow-needle assembly from the rest position into the connection position, wherein the guide device has at least one guide pin which slides in at least one associated guide groove during the displacement from the rest position into the connection position, - wherein the guide device is configured such that the displacement of the hollow-needle assembly from the rest position into the connecting position is irreversible,