Patent ID: 7281279

Claim:
A drain valve, which is assembled on a rotating element of a water tank and is adapted to cooperate with a handle and a link element of the water tank for controlling opening or stopping a drain hole of the water tank, comprising: a fixing base forming outer screw threads on an outer peripheral of a lower portion thereof, a plurality of vent holes being distributed at an outer peripheral of a bottom of the fixing base, a plurality of flanges extending upwardly from an inner edge of the fixing base, wherein each flange forms an anchor outwardly; a cover assembled on the anchors of the fixing base and having an inner surface and an outer surface, wherein a positioning flat being formed at the inner surface, a lift portion projecting at the outer surface and connecting with the link element of the water tank, and at least one support arm being formed at the outer surface for mounting on the rotating element of the water tank; a stop pad arranged between the cover and the fixing base; and a float being hollow and generally tapered, and defining inner screw threads on an inner peripheral of an upper portion thereof for engaging with the outer screw threads of the fixing base whereby rotation of said float with respect to said fixing base, about said outer and inner screw threads, will adjust the amount of said vent holes that is exposed to an exterior of said valve, a plurality of flow holes being defined at a bottom of the float for allowing water in or out.