passed through a mixing device 130 that mixes the liquid with a concentrate stored in the concentrate reservoir 147 as shown the venturi 140 is the preferred mixing device the venturi 140 may be either a fixed concentration venturi or a variable concentration venturi to initiate flow through the venturi 140 the activation valve 145 such as an air actuated ball valve or a solenoid valve is opened thereby allowing liquid to flow into the inlet side 142 of the venturi 140 as the liquid flows from the inlet side 142 to the outlet side 146 of the venturi 140 concentrate from the concentrate reservoir 147 is drawn through the suction 144 and entrained in the flow of liquid the ratio selector 148 is used to adjust the amount of concentrate entrained for a given flow rate and therefore to adjust the concentration of the resulting liquid mixture as shown the flow of liquid through the venturi 140 is controlled by a trigger activated wand for manually applying the liquid mixture to a desired surface alternately the liquid mixture can be directed to an automatic spray device not shown or a receiver tank 180 fig3 as previously noted an electronic controller 160 can be used to operate the system 100 when such a device is used the operation of the pressurized gas source 120 gas fittings 114 liquid fill fittings 112 liquid fill control device 118 and activation valve 145 are all synchronized so that the system functions in an automatic.