In order to decalcify a liquid ring machine economically and in a short time, reliably preventing the liquid ring machine from being blocked during its standstill phase by the consolidation of lime sludge, a device (7; 9; 11; 12) is provided for decalcifying its inner surfaces and/or sealing gap wetted by the working liquid and/or by the pumping medium. Preferably this device has at least one annular channel arranged in a disk cam (1) or in the impeller (2) for distributing a lime-dissolving rinsing liquid.
