a paint circulating system is suitable for providing paint to applicators in a product finishing facility . the system includes a pump for pumping paint around the system and a back - pressure regulator , which substantially eliminates pressure fluctuations of paint in the system upstream of the bpr . a controller is provided for controlling the pump and the bpr to operate in one of a flow mode , wherein a required flow rate of paint around the system is maintained , and a pressure mode , wherein a pressure of paint between the pump and the bpr is maintained . the paint circulating method includes switching operation of the pump and the bpr between the flow mode and the pressure mode .