Flushing characteristics of a tower tankvalve flushing system with a 12-inch-diametermanual valve were determined. Data wereobtained using the outside cow alleys in a fourrowfreestall barn. The alleys were 12 ft wideand 420 ft long with a 2% slope. The averageflow rate exceeded 8,000 gallons per minute(gpm) when the average head was above 30 ftand the manual valve opened 80 degrees.Opening the valve to 90 degrees increased theflow rate to over 9,700 gpm. The velocity ofthe flushing wave was 8.5 fpm with a flow depthof 3.5 in. The estimated wave duration or alleycontact time was 14.6 sec with a 25-40 secrelease time from the flush tank. The flow rateranged from 5,300 gpm to 7,200 gpm when theaverage head was between 16 and 28 ft.
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