| 摘要 |
1,190,886. Swimming baths. FILTRATION EQUIPMENT CORP. 6 May, 1968 [5 May, 1967], No. 21382/68. Heading A4N. [Also in Division B1] A gravity-flow floating filter 10 is backwashed by causing it to sink in the pool of filtrate 11 in which it floats. As described with reference to a floating swimming-pool 13, a pump 45 forces dirty water from a main body e.g. a river 12 into a gullet 28 surrounding a "rapid sand" filter 10a of the cellular type disclosed in U.S.A. Specification 3,080,062. The liquid level L 1 is maintained by controlling pump 45 by a float-operated switch 47. Filtrate leaves through the filter base and enters the pool, whose level L 2 is maintained by scuppers 16. A pontoon 20 causes the filter body 10 to float. To cleanse the filter a bleed valve (42) (Fig. 1, not shown) in line 38 is opened, allowing supernatant air to escape from pontoon 20 so that the latter sinks, Fig. 3 (not shown), causing backwashing of the filter by rising filtrate. Dirty backwash is discharged through line 52. A platform 17 extends inwardly of the pool around its entire periphery. |
