Page History

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1) Raw water enters 55 gallon drum and passes through sand filter.
2) Filtered water enters screen pipe and flows to clear well.
3) As filter clogs, head loss increases in region "A". This backpressure causes flow to be directed up siphon. The column of water in the siphon rises and eventually passes turn, where flow accelerates, creating a low pressure in region "A". The pressure differential between A and B induces backwash cycle from clear well.
4) Siphon is broken by small pipe exposed to atmosphere, and remaining backwashed water goes to wasteOnce the siphon fills backwash can be started.
4)Backwash begins when the operator opens both siphon valves and shuts off raw water inflow.
5)The flow out of the siphon creates a low pressure in top of barrel and flow from clear well expands sand bed and backwashes filter.
6)Backwash is stopped by closing upper valve of siphon and remaining backwashed water stays in column. At this point filter has been backwashed and continues operating as normal.

• Interface between sand and effluent pipe has not yet been determined. Possibilities include gravel or screen pipe, respective head losses under investigation

Image Removed; the siphon remains primed.