Abstract: A portable mixing-dispensing device having a manual flow control valve means between a ventable flow control chamber and a solution-proportioning chamber, and a manual feed valve between the proportioning device and a source of concentrate supplied at a negative gauge pressure, same including means to selectively coordinate the operation of the valves. The feed valve serves also as an anti-backflow check valve for the concentrate supplied under a negative gauge pressure as well as maintaining the prime thereof without dilution when concentrate is not being supplied to the mixing chamber. A translucent concentrate supply tube readily visible from above the mixing chamber serves as a visual check as to the prime of the concentrate.