CON-V-AIR’s indirect injection system makes it possible to prepare a solution of variable concentration in an overflow basin. In this system, water is used as the conveying medium, and it is by fluctuating the speed of the screw that the outflow is increased or decreased. Since this is an indirect system, when the operator changes the screw speed, there will be a delay before the new flow rate is reached (unlike our direct injection system, which allows much faster flow fluctuation).