a process and apparatus to guide spray material such as paints and lacquers to a plurality of spraying stations by a common ring line for spray material ; in the process and apparatus , pressure , speed , volume flow and / or mass flow of the spray material flowing in the ring line are continuously monitored and adjusted to the respective requirements such that the spray material flowing in the ring line is conserved as such as possible . thus , negative effects on the quality of the spray material are avoided even with long circulation times for the spray material .