| 摘要 |
<p>Filtration apparatus (10) includes a central inlet tube (11) which supports an annular plate (12) from which a number of filtration chambers (13) and an outlet (14) are suspended. Backwash equipment (20) includes a rotatable assembly (24) which can be driven by motor assembly (21) to successively engage an L-shaped passage (27) with the inlet of each filtration chamber (13) and thereby connect in to a backwash outlet (30). During normal filtration this outlet is closed by a ball (31). The ball (31) is retained on the rotatable shaft (25), which defines passage (27), so that as the backwash cycle starts the ball (31) is unseated and from the outlet (30) and not reseated until the cycle is complete.</p> |
