| 摘要 |
<p>In order to assist rotation of the radial distributor arms (5, 6, 7 and 8) of a sprinkler (3) of a percolating biological filter, vanes (11 and 12) are mounted on a diametrically opposed pair of the arms (5 and 7). Each vane (11, 12) is pivotally movable so as to offer less resistance by feathering when it moves into the wind than when it moves in the same direction as the wind. The degree of pivotal movement of each vane (11, 12) is conveniently limited to about 45 DEG on each side of a mid-point position in which the vane is perpendicular to the radial distributor arm. <IMAGE></p> |
