A fluid flow control valve system has a plurality of pairs of 3 port, 2 position
(3/2) control valves (6, 6) each valve being movable between its
two positions by a pair of electrically-operable actuators (1, 2). A logic
controller selectively generates electrical control signals for independently controlling
operation of the pairs of 3/2 control valves, and a circuit means (11) is
associated with each 3/2 control valve pair (6, 6) to receive the
control signals and provide electrical outputs to eit actuators (1, 2) of
each 3/2 control valve of each pair. Variable switch means (14) forming
part of the circuit means (11) pr the actuators (1, 2) to which the
output is applied. Varying the switch means (14) programmes the fluid output
mode of each 3/2 control valve pair to provide any one of a number of different
effective valve types.