The invention concerns a coating plant for the coating of construction units with a coating medium, in particular a paint system for the lacquer finish of motor vehicle body parts, with a dosing pump, the coating medium supplied with a certain delivery (Fm) proportioned, and a pressure control valve arranged upstream before the dosing pump to adjust a coating medium pressure (p v) at the entrance of the dosing pump, as well as a control unit to adjust the pressure control valve a controlled variable of the pressure difference (Δp) through the dosing pump independently of the delivery of the dosing pump and the changing viscosity of the lacquers to an essentially constant desired value (ΔpTARGET).