Abstract: A system for supplying dampening fluid to a rotating cylinder of a printing press which includes first and second closed tanks containing the dampening fluid. To move the dampening fluid from one of the first or second tanks compressed air a control pressure proportional to the speed of the press pressurizes one of the tanks. The control pressure in turn causes the dampening fluid to move from one of the tanks through the interconnecting piping to be sprayed onto the cylinder at a flow rate proportional to the speed of the press. To transfer the control pressure from the first to the second tank and provide a constant supply of dampening fluid at the flow rate proportional to the speed of the cylinder means to transfer between the first and second tanks are provided. The transferring means includes providing a quantity of compressed air at the control pressure through a restriction to the nonsupplying tank for a period of time to pressurize the nonsupplying tank to the control pressure.