A spray system comprises: a fluid source for a spray fluid; a sprayer (28, 30) disposed to spray the spray fluid; a pump comprising: a metered double-action pumping cylinder with a reciprocating plunger; first and second inlet valves (102 and 104); and first and second outlet valves (106 and 108); the first and second inlet valves (102 and 104) being up and down inlet valves, respectively, and the first and second outlet valves (106 and 108) being up and down outlet valves, respectively; wherein the up inlet and up outlet valves (102 and 106) are open and the down inlet and down outlet valves (104 and 108) are closed while the reciprocating plunger travels upward; and wherein the up inlet and up outlet valves (102 and 106) are closed and the down inlet and down outlet valves (104 and 108) are open while the reciprocating plunger travels downward; and a controller configured to transmit a first signal causing the first inlet and outlet valves (102 and 106) to close for pump changeover, and further configured to transmit a second signal while the first inlet and outlet valves are closing, the second signal causing the second inlet and outlet valves (104 and 108) to begin opening, wherein the controller is configured to perform the following steps: signal the reciprocating plunger to stop for a changeover period; transmit the first signal before the reciprocating plunger has stopped for the first inlet and outlet valves (102 and 106) to close, whereby the first inlet and outlet valves start to mechanically close when the reciprocating plunger stops; transmit the second signal while the reciprocating plunger is slowing to a halt for the second inlet and outlet valves (104 and 108) to open, such that the second inlet and outlet valves begin to mechanically open at least a dwell period after the first inlet and outlet valves have entirely closed; and command the reciprocating plunger such that the reciprocating plunger begins moving while the second inlet and outlet valves are opening. a fluid source for a spray fluid; a sprayer (28, 30) disposed to spray the spray fluid; a pump comprising: a metered double-action pumping cylinder with a reciprocating plunger; first and second inlet valves (102 and 104); and first and second outlet valves (106 and 108); the first and second inlet valves (102 and 104) being up and down inlet valves, respectively, and the first and second outlet valves (106 and 108) being up and down outlet valves, respectively; wherein the up inlet and up outlet valves (102 and 106) are open and the down inlet and down outlet valves (104 and 108) are closed while the reciprocating plunger travels upward; and wherein the up inlet and up outlet valves (102 and 106) are closed and the down inlet and down outlet valves (104 and 108) are open while the reciprocating plunger travels downward; and a metered double-action pumping cylinder with a reciprocating plunger; first and second inlet valves (102 and 104); and first and second outlet valves (106 and 108); the first and second inlet valves (102 and 104) being up and down inlet valves, respectively, and the first and second outlet valves (106 and 108) being up and down outlet valves, respectively; wherein the up inlet and up outlet valves (102 and 106) are open and the down inlet and down outlet valves (104 and 108) are closed while the reciprocating plunger travels upward; and wherein the up inlet and up outlet valves (102 and 106) are closed and the down inlet and down outlet valves (104 and 108) are open while the reciprocating plunger travels downward; and a controller configured to transmit a first signal causing the first inlet and outlet valves (102 and 106) to close for pump changeover, and further configured to transmit a second signal while the first inlet and outlet valves are closing, the second signal causing the second inlet and outlet valves (104 and 108) to begin opening, wherein the controller is configured to perform the following steps: signal the reciprocating plunger to stop for a changeover period; transmit the first signal before the reciprocating plunger has stopped for the first inlet and outlet valves (102 and 106) to close, whereby the first inlet and outlet valves start to mechanically close when the reciprocating plunger stops; transmit the second signal while the reciprocating plunger is slowing to a halt for the second inlet and outlet valves (104 and 108) to open, such that the second inlet and outlet valves begin to mechanically open at least a dwell period after the first inlet and outlet valves have entirely closed; and command the reciprocating plunger such that the reciprocating plunger begins moving while the second inlet and outlet valves are opening. signal the reciprocating plunger to stop for a changeover period; transmit the first signal before the reciprocating plunger has stopped for the first inlet and outlet valves (102 and 106) to close, whereby the first inlet and outlet valves start to mechanically close when the reciprocating plunger stops; transmit the second signal while the reciprocating plunger is slowing to a halt for the second inlet and outlet valves (104 and 108) to open, such that the second inlet and outlet valves begin to mechanically open at least a dwell period after the first inlet and outlet valves have entirely closed; and command the reciprocating plunger such that the reciprocating plunger begins moving while the second inlet and outlet valves are opening.