1

Absolute or dynamic viscosity

problems

5.1 A bar screen measuring 2 m by 5 m of surficial flow area is used to protect the pump in a shoreline intake of a water treatment plant. The head loss across the screen is 0.17 m. The bar width is 20 mm and the bar spacing is 70 mm. If the screen is 30% clogged, at what rate of flow is the plant drawing water from the intake? Assume Cd = 0.84.

5.2 A water treatment plant drawing water at rate of 8 m /s from a shoreline intake is protected by bar screen measuring 2 m by 5 m. The head loss across the screen is 0.17 m. The bar width is 20 mm and the bar spacing is 70 mm. If the screen is 30% clogged, what is the area of the clear space opening of the bars? Assume Cd = 0.84.

5.3 A water treatment plant drawing water at rate of 8 m /s from a shoreline intake is protected by bar screen. The head loss across the screen is 0.17 m. The bar width is 20 mm and the bar spacing is 70 mm. Assuming that the screen is 30% clogged and using the clear space opening in Problem 5.2, calculate the value of Cd.

5.4 A bar screen measuring 2 m x 5 m of surficial flow area is used to protect

a pump. The approach area to the screen is 7.48 m and the head loss across it is 0.17 m. The bar width is 20 mm and the bar spacing is 70 mm. If the screen is 30% clogged, at what rate of flow is the pump drawing water? Assume Cd = 0.84.

5.5 A water treatment plant is drawing water at rate of 8 m /s and its intake is protected by a bar screen measuring 2 m x 5 m. The head loss across the screen is 0.17 m. The bar width is 20 mm and the bar spacing is 70 mm. If the screen is 30% clogged, what is the area of the clear space opening of the bars? Assume Cd = 0.84 and that the approach area is 7.48 m2.

5.6 A water treatment plant drawing water at rate of 8 m /s is protected by bar screen. The head loss across the screen is 0.17 m. The bar width is 20 mm and the bar spacing is 70 mm. Assuming that the screen is 30% clogged and using the clear space opening in Problem 5.5, calculate the value of Cd. The approach area is 7.48 m . Assuming the head loss across the screen is 0.2 m and using this newly found value of Cd, what is the approach area?

5.7 The terminal settling velocity of a spherical particle having a diameter of 0.6 mm is 0.11 m/s. What is the mass density of the particle? Assume the settling is type 1 and the temperature of the water is 22°C. What is the drag coefficient?

5.8 The terminal settling velocity of a spherical particle having a diameter of 0.6 mm is 0.11 m/s. Assuming the specific gravity of the particle is 2.65, at what temperature of water was the particle settling? Assume the settling is type 1 and use the value of the drag coefficient in Problem 5.7.

5.9 The terminal settling velocity of a spherical particle is 0.11 m/s. Its specific gravity is 2.65 and the temperature of the water is 22°C. What is the diameter of the particle? Assume the settling is type 1. What is the drag coefficient?

5.10 The terminal settling velocity of a worn sand particle having a sieve diameter of 0.6 mm is 0.11 m/s. What is the mass density of the particle? Assume the settling is type 1 and the temperature of the water is 22°C. What is the drag coefficient?

5.11 The terminal settling velocity of a worn sand particle having a sieve diameter of 0.6 mm is 0.11 m/s. Assuming the specific gravity of the particle is 2.65, at what temperature of water was the particle settling? Assume the settling is type 1 and use the value of the drag coefficient in Problem 5.10.

5.12 The terminal settling velocity of a worn sand particle is 0.11 m/s. Its specific gravity is 2.65 and the temperature of the water is 22°C. What is the sieve diameter of the particle? Assume the settling is type 1. What is the drag coefficient?

5.13 A certain municipality in Thailand plans to use the water from the Chao Praya River as raw water for a contemplated water treatment plant. The river is very turbid, so presedimentation is necessary. The result of a column test is as follows:

If the percentage removal of particles is 71.58, what is the hydraulic loading rate? The column is 4 m deep.

5.14 In Problem 5.13, what is the fraction not completely removed xo?

5.15 In Problem 5.13, what fraction in xo is removed?

5.16 A grit removal unit consists of four identical channels to remove grit for