In a headloss test, a 30 ft by 10 ft filter loses 6 inches of head in 4 minutes. What is the rate of filtration in gallons per minute per square foot?

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Multiple Choice

In a headloss test, a 30 ft by 10 ft filter loses 6 inches of head in 4 minutes. What is the rate of filtration in gallons per minute per square foot?

Rate of filtration is the volume of water passing through the filter per minute per square foot of filter area. A headloss of 6 inches equals 0.5 feet of head across a filter area of 30 ft by 10 ft, which is 300 ft^2. The corresponding volume is 300 × 0.5 = 150 ft^3. Convert to gallons: 150 × 7.48 ≈ 1122 gallons. Over 4 minutes, that’s about 1122 / 4 ≈ 281 gpm. Per square foot, 281 / 300 ≈ 0.94 gpm/ft^2, which is about 0.9 gpm/ft^2.

Rate of filtration is the volume of water passing through the filter per minute per square foot of filter area. A headloss of 6 inches equals 0.5 feet of head across a filter area of 30 ft by 10 ft, which is 300 ft^2. The corresponding volume is 300 × 0.5 = 150 ft^3. Convert to gallons: 150 × 7.48 ≈ 1122 gallons. Over 4 minutes, that’s about 1122 / 4 ≈ 281 gpm. Per square foot, 281 / 300 ≈ 0.94 gpm/ft^2, which is about 0.9 gpm/ft^2.

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