Air injector

This is a device for injecting air into a water supply under pressure in a closed system. One embodiment consists of two sliding pistons inside a closed housing. The two pistons are connected to each other by a connecting rod. They are positioned so that they slide alternately toward one end of said housing and then toward the other end. They are propelled first in one direction and then the other by water entering under pressure alternately through two openings, one on each side of the driving piston and exiting alternately through two other openings on opposite sides of said driving piston. These valves are opened and closed alternately in pairs by a means driven by the movement of said pistons. The second piston, driven by the first, draws air into said housing as it moves in one direction and then forces it into the water as it moves in the other direction.