The invention relates to a method for preventing and detecting coolant discharges from complex hydraulic systems. The aim of the invention is to configure such a method in such a way that this method in particular meets requirements for preventing/limiting the development of explosive atmospheres in working areas and for reducing measures from previously otherwise typical requirements for Ex zones. This aim is achieved in that a circuit carrying coolant is divided into small volumes that have stop valves and a relief valve, wherein a leak detection diagnosis can be carried out by means of a pressure sensor that can be integrated.