The present invention relates to a pressure-increasing unit (1) comprising first receiving means (2) for receiving a pipeline (4) conveying pressurized gas, at least one first pipeline (3) for further transferring the pressurized gas to applications utilizing it, and second receiving means (6) for receiving a second pipeline (5) conveying reduced-pressure gas returning from the applications. The present solution is characterized in that the receiving means (6) are connected with at least one pressure intensifier (7). This pressure intensifier, in turn, is connected to the first receiving means (2) receiving pressurized gas for transferring gas re-pressurized by a substitution means (8) back to the applications utilizing it.