Backflow safety valve for therapy pools

Claim 1

An air supply system for a therapy pool comprising an air supply blower, an air supply line connected to and supplied with air from said blower, a plurality of water outlets connected to said air supply line for projecting water into said pool, said water outlets being of the type in which blockage of said water outlets may cause water to enter said air supply line under pressure from a water supply line, a backflow safety valve, said valve being fully automatic in operation, said valve comrising a cylindrical body connected at its opposite ends in a vertical position within said air supply line between said water outlets and said air supply blower, said valve having a valve member comprising an inverted cup mounted for longitudinal movement within said valve body, said cup having a closed end adapted to engage an annular valve seat formed within said valve body adjacent to the closed end of said cup, said cup normally being disposed in an open downward position, said cup being movable upwardly by the pressure of water flowing through said air supply line and into the open end of said cup to move said cup longitudinally upwardly within said valve body into sealing engagement with said valve seat to prevent water from reaching and damaging said air supply blower, said cup automatically returning downwardly to open position upon the flow of water out of said cup.