## Info

absolute or dynamic viscosity

problems

4.1 Water at a temperature of 22°C is to be conveyed from a reservoir with a water surface elevation of 70 m to another reservoir 300 m away with a water surface elevation of 20 m. Determine the diameter of a steel pipe if the flow is 2.5 m /s. Assume a square-edged inlet and outlet as well as two open gate valves in the system.

4.2 For the pump represented in Figure 4.8, determine the discharge when the pump is operating at a head of 20 m at a speed of 1,100 rpm.

4.3 Calculate the efficiency and power for the pump in Problem 4.2.

4.4 If the pump in Problem 4.2 is operated at 1,170 rpm, calculate the resulting

4.5 If a homologous 30-cm pump is to be used in Problem 4.2, calculate the resulting H, Q, Pbrake, and n for the same rpm.

4.6 The outlet manometric head at the discharge of a pump is equal to the equivalent of 50 m of water. If the discharge velocity is 2.0 m/s, what is the outlet dynamic head?

4.7 You are required to recommend the type of pump to be used to convey wastewater to an elevation of 8 m above a sump. Friction losses and the velocity at the sewage discharge level are estimated to be 3 m and 1.30 m/s, respectively. The operating drive is to be 1,200 rpm. Suction friction losses are 1.03 m; the diameter of the suction and discharge lines are 250 mm and 225 mm, respectively. The vertical distance from the sump pool level to the pump centerline is 2 m. What type of pump would you recommend?

4.8 In Problem 4.7, if the temperature is 20°C, has cavitation occurred?

4.9 Compute the inlet and outlet manometric heads in Problem 4.7.

4.10 In Problem 4.7, what are the inlet and outlet dynamic heads? From the values of idh and odh, calculate TDH.

4.11 In Problem 4.7, what is the NPSH?

4.12 In Example 4.8, calculate the percent errors in the answers if the characteristic curves of the pumps are not corrected for the station losses.

4.13 What is -htp + hp equal to? Explain why this expression is given this name.

4.14 What is the name given to the pressure that is equivalent to the pressure head?

4.16 It is desired to pump a wastewater to an elevation of 30 m above a sump. Friction losses and velocity at the discharge side of the pump system are estimated to be 20 m and 1.30 m/s, respectively. The operating drive is to be 1,200 rpm. Suction friction losses are 1.03 m; the diameter of the suction and discharge lines are 250 mm and 225 mm, respectively. The vertical distance from the sump pool level to the pump centerline is 2 m. If the temperature is 10°C, has cavitation occurred?

4.17 What are the inlet and outlet manometric heads in Problem 4.16?

4.18 What are the inlet and outlet total dynamic heads in Problem 4.16? From the values of the idh and odh, calculate TDH.

4.19 In relation to hlp, discuss the relationship of hp and hbrake.

4.20 Show all the steps in the derivation of Equation (4.27).

4.21 It is desired to pump a wastewater to an elevation of 30 m above a sump. Friction losses and velocity at the discharge side of the pump system are estimated to be 20 m and 1.30 m/s, respectively. The operating drive is to be 1,200 rpm. The diameter of the suction and discharge lines are 250 mm and 225 mm, respectively. The vertical distance from the sump pool level to the pump centerline is 2 m. If the temperature is 10°C and the inlet manometric head is -3.09 m, what are the suction friction losses?

4.22 In Problem 4.21, what is the head given to the pump?

4.23 Pump characteristics curves are developed in accordance with the setup of Figure 4.7. The discharge flow is 0.15 m /s and the outlet diameter of the discharge pipe is 375 mm. The motor driving the pump is 50 hp. Calculate the gage pressure at the outlet of the pump.

4.24 Pump characteristics curves are developed in accordance with the setup of Figure 4.7. The pressure at the outlet of the pump is found to be 196 kN/m gage. The outlet diameter of the discharge pipe is 375 mm. The motor driving the pump is 50 hp. Calculate the rate of discharge.

4.25 Pump characteristics curves are developed in accordance with the setup of Figure 4.7. The pressure at the outlet of the pump is found to be 196 kN/m gage. The outlet diameter of the discharge pipe is 375 mm. If the rate of discharge is 0.15 m /s, calculate the input brake power to the pump.

4.26 In Problem 4.25, if the brake efficiency is 65%, calculate Po, hbrake, and Vo.

4.27 If the pump in Example 4.4 has a power input of 30 kW, determine the rpm.

4.28 In Problem 4.27, calculate the resulting H.

4.29 In Problem 4.27, calculate the resulting Q and n

4.30 If a homologous 40-cm pump is to be used for the problem in Example 4.5, calculate the resulting H, Q, Pbrake, and n for the same rpm.

4.31 A designer wanted to recommend the use of an axial-flow pump to move wastewater to an elevation of 50 m above a sump. Friction losses and velocity at the discharge side of the pumping system are estimated to be 20 m and 1.30 m/s, respectively. The operating drive is to be 1,200 rpm. Suction friction losses are 1.03 m; the diameter of the suction and discharge lines are 250 mm and 225 mm, respectively. The vertical distance from the sump pool level to the pump centerline is 15 m. Is the designer recommending the right pump? What is the net positive suction head? Is the pumping possible?

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