Abstract: A float controlled valve has a chamber and a first diaphragm forming a part of the chamber walls; a passage admits liquid from the valve inlet to the chamber; a second diaphragm forms a further part of the chamber walls and has a bleed-off passage which may be closed by action of the float; pressure build up in the chamber acts on the first diaphragm to close the valve; the pressure build up also acts on the second diaphragm to deflect the bleed off passage and so depress the float below the liquid surface when the valve closes; a sharp pointed and reduced diameter entrance to the passage at the valve inlet reduces blockage likelyhood; a helix on the float actuated means for closing the bleed-off passage provides facility for adjustments.