Compressed-air powered suction units generate a vacuum with compressed gas, usually air. For conversion of the compressed air into a vacuum, an ejector is used. The ejector can be connected to the central system of compressed gas directly or with a connector on a flexible tube, while compressed gas from a cylinder can also be used. A button for fine and rough vacuum regulation, a manometer (from 0 to -1.0 bar) for display of the currently selected vacuum power, a silencer, connecting accessories, a bacterial filter and an optional safety jar with a shut-off valve, which prevents liquid from entering the device, are installed on the ejector. In combination with various suction jars an ejector can form: - portable suction unit with reusable suction jars, - portable suction unit with suction bags for single use, - mobile suction unit for field operation.