Siphon with a priming chamber

A siphon with priming chamber 1 containing upstream one way valve 4, downstream one way valve 5, a venturimeter 13, a vacuum break valve 7 and an air diffuser 21. The vacuum break valve is attached to a float 9 via stem 8. The venturimeter is attached to a pump used to draw air out of the chamber, this causes a drop in pressure within the chamber allowing external atmospheric pressure to depress vacuum break valve 7 and float 9, forcing valve 5 shut and allowing water to be drawn into the priming chamber through valve 4. As the water rises the buoyancy of float 9 shuts off a venturi valve 17, opens vacuum valve 7 breaking the vacuum and allowing air into the priming chamber; upstream one way valve 4 shuts and the downstream one way valve 5 opens so water from the chamber flows out of a downstream pipe. As the water level drops float 9 descends and the vacuum break valve seals the chamber again. At this point the upstream one way valve 4 opens and the siphon begins to discharge. The air diffuser 21 is used to regulate the flow through the siphon.