In normal applications, over half of hydraulic systems are heavily contaminated and directly responsible for over 2/3 of the total cost of maintenance. Controils is the spin-off of La Ricambi Udinese which for more than thirty years has been offering its know-how wherever there are functions that use fluids: power transmission systems, purification systems, machines in general, cooling systems, ventilation and smoke extraction, etc. The cases reported here testify to the effectiveness and value of a consolidated method recognized by an international clientele.