Pressurized seal such as for drum screens

Claim 1

In a drum screen apparatus for screening raw water and the like and including a stationary structure including a raw water delivery channel and a screened water holding tank wherein a given elevation of screened water is maintained and further including a drum disposed to receive water from said channel and to rotate within said tank on a horizontal axis with the uppermost section of its cylindrical surface above said elevation for cleaning purposes, said structure and said drum having interfacing sealing surfaces, said structure having a wiping seal mounted on its sealing surface so as to engage the sealing surface on said drum and prevent any passage of raw water therebetween from said channel into said tank, an improved wiping seal for said apparatus comprising (A) a flexible, elongated element including (1) a tubular body defining a distribution chamber having opposite ends, said body being of trapezoidal section and having larger and smaller parallel sides and two converging sides, (2) spaced, parallel wiping flanges extending from the two converging sides and in wiping engagement with the sealing surface of said drum, (3) a series of ports in the smaller side and between said flanges and opening from said chamber, (B) means closing said opposite ends of said distribution chamber, (C) a clean water supply connection opening into said chamber at one or both of said opposite ends thereof and (D) means securing the larger side to the sealing surface on said structure with said opposite ends adjoining each other above said elevation and so that the smaller side is axially offset toward said channel such that the larger side pivots and the smaller side cooperatively bows outwardly to compensate for variations in the annular space between the sealing surfaces, said seal being adapted to be supplied with clean water at a pressure which prevents raw water from passing said seal where such wiping engagement may not occur.