Patent ID: 6874172

Claim:
A device for immersion in fluid, in a cistern, which comprises: a housing having an upper portion and a lower portion; an upwardly movable main valve assembly within the housing and forming therewith a variable volume upper chamber and a lower chamber; an outlet provided in the lower housing portion; a seat for the main valve assembly provided in the lower housing portion at the entry to the outlet so that in the lowered position of the main valve assembly the outlet is blocked to prevent fluid in which the device is immersed from flowing through the outlet: a central stem extending upwardly from the main valve assembly and actuable by a first operating means remotely from the upper housing to raise the main valve assembly off its seat, the main value assembly being formed underneath with a surface arranged so that on raising of the main valve assembly it is subjected to upwards force by fluid flowing from the lower chamber into the outlet thereby causing the assembly to rise to the top of the upper chamber and permit full flow of the immersion fluid through the outlet whereupon the cessation of flow as a result of substantially complete discharge of all the immersion fluid causes the main valve assembly to revert to its seated position; and a second operating means, which is also actuable remotely from the upper housing, which is operable to raise, separately and independently of the first operating means, the main valve assembly off its seat and then to exert or enable to be exerted a downward force on the main valve assembly when the main valve assembly is in a raised position, sufficient to exceed the upwards, water level dependent, flow reaction force acting upwards on the underneath surface of the main valve assembly so that the main valve assembly re-seats at a predetermined level before complete discharge of all the immersion fluid so that there is a partial discharge of the fluid, the second operating means comprising means for raising the main valve assembly and means for engaging and exerting a downward force to act on and engage with the central stem to cause partial discharge of the immersion fluid.