A very common control scheme is split range control in which the output of a controller is split to two or more control valves. For example: Controller output 0% Valve A is fully open and Valve B fully closed. Controller output 25% Valve A is 75% open and Valve B 25% open. Controller output 50% Both valves are 50% open. Controller output 75% Valve A is 25% open and Valve B 75% open. Controller output 100% Valve A is fully closed and Valve B fully open. Different arrangements are possible. For example, figure 1 shows a split range pressure controller on a separator with two valves, one to the flare and one to the compressor suction. In this case, the