Diaphragm operated float controlled valve

A float valve which comprises a conduit for liquid, a valve seat located at an intermediate position of the conduit, a valve closure member movable when actuated onto the valve seat to close the valve and off the valve seat to open the valve, a passage whose entrance is located upstream of the valve seat and whose entrance is pointed upstream, a control chamber, the passage leading to the control chamber, the walls of which are formed in part by a first diaphragm and a second diaphragm, the first diaphragm being connected with the closure member so as to actuate it, the surface of the first diaphragm being of larger area than the cross sectional area of the conduit encompassed by the valve seat, the second diaphragm carrying a bleed off passage having a seat at its outer end, a bleed off passage closure bung, a float, a float connection linkage providing a mechanical connection between the float and the bung, the linkage adapted to cause the bung to move onto the bleed-off passage seat when the level of the float rises, and the linkage adapted to depress the float below the level of the liquid body if the second diaphragm is deflected outwardly and hence the bleed off passage moves outwardly, while the bung is on the bleed off passage.