Abstract: The invention relates to a method for generating a scale-removing or coat-applying system based on a vacuum-balancing low-pressure multicomponent two-phase fluid flow. A cleaning site such as, e.g., a pipe circuit (A) or the inner cavities of a heat exchanger (B) is supplied with an already used cleaning agent in a two- or multiphase flow made up of ca. 10% liquid and ca. 90% air or gas, which after separation is used again by way of continuously monitoring the ion density of the separated liquid, using a conductivity apparatus which determines whether it shall be filtered and reused, be supplied with new liquid and/or solids, or be dumped. A liquid flow and separated air/gas flow from an air pump meet at a mixing point from where an intended two-phase flow flows to the cleaning site (A), (B), or similar, through this and then forward to return as a re-use medium. A gas-injected liquid/powder flow from a mixing unit is also used for coating, e.g.