Patent ID: 7284569

Claim:
A steam valve comprising: a steam inlet; a valve body for regulating a flow of steam entering into the valve body through the steam inlet; a valve casing accommodating the valve body and communicated with the steam inlet; a strainer arranged between the valve body and the valve casing so as to surround the valve body, and adapted to remove a foreign object contained in the steam; and a screen assembly mounted to an outer peripheral portion of the strainer, said screen assembly including at least one screen unit formed from a perforated plate, wherein said strainer has a cylindrical structure and said perforated screen assembly is mounted on the outer peripheral portion of the cylindrical strainer; and said screen assembly is formed with a number of perforations, and when a side portion of the screen assembly mounted on the peripheral portion of the cylindrical strainer is developed, the perforations formed to the screen assembly have an arrangement in a fashion that centers of neighboring three perforations constitute vertexes of a regular triangle having one side of a length corresponding to a pitch “a” of adjacent two perforations, the pitch “a” being a sum of a diameter “d” of the perforations and a distance L between the adjacent two perforations, the diameter “d” and pitch “a” being set to optional values, respectively, in accordance with the arrangement of the screen assembly relative to the strainer.