A device includes a pressure container, a pressure reducer, and a valve. The pressure container contains a liquid container deformable under pressure. The pressure reducer provides a liquid which bears with a first (e.g., lower) pressure against a first connector of the pressure reducer and with a second (e.g., higher) pressure at a second connector of the pressure reducer. The first connector is connectable to the liquid container, and the second connector is accessible from outside the pressure container. Due to the pressure reducer, liquid from the liquid container can be provided with a second pressure at the second connector. The valve adds a gas to at least part of the interior space of the pressure container remaining after receipt of the liquid container, the gas having an overpressure, such that a liquid in the liquid container bears with the first pressure against the first connector.