Fluid Mechanics
8th Edition
ISBN: 9780073398273
Author: Frank M. White
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 11, Problem 11.43P
The 28-in-diameter pump in Fig. 11.7a at 1170 r/min is used to pump water at 20°C through a piping system at 14,000 gal/min. (a) Determine the required brake horsepower. The average friction factor is 0.018. (b) If there is 65 ft of 12-in-diameter pipe upstream of the pump, how far below the surface should the pump inlet be placed to avoid cavitation?
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Water at 90°C is to be pumped from a low-elevation reservoir to a high-elevation reservoir at a
flow rate of 0.0046 cu. meter per second, as shown in the figure below. The atmospheric
pressure at the location of the pump installation is 98.4 kPa. The 40-mm-diameter suction pipe
has a total length of 7.2 m. The friction factor for the suction pipe is estimated to be 0.025. The
centrifugal pump that will be used has an NPSHR of 4.5 m. Will cavitation occur in this pump
setup?
5 m
↓
(A) Yes, cavitation will occur with NPSHA equal to 4.80 m.
B) Yes, cavitation will occur with NPSHA equal to -5.20 m.
No, cavitation will not occur with NPSHA equal to 4.80 m.
(D) No, cavitation will not occur with NPSHA equal to -5.20 m.
(pump centerline)
19 m
The 28-in-diameter pump in Fig. 11.7a at 1170 r/min is
used to pump water at 20°C_through a piping system at
14,000 gal/min. (a) Determine the required brake horse-
power. The average friction factor is 0.018. (b) If there is
65 ft of 12-in-diameter pipe upstream of the pump, how far
below the surface should the pump inlet be placed to avoid
cavitation?
2. A centrifugal pump installation has been designed to discharge 0.126 m^3/s of brine (sp.gr. = 1.2). The suction pipe is 305 mm and is at the same level as the discharge pipe which is 203 mm in diameter. At the centerline of suction flange, the vacuum is 154.2 mm Hg. The discharge pressure gauge reads 0.1379 MPa and is connected 1.22 m above the discharge flange centerline. The pump is driven by a 35 KW electric motor that will not carry overload and has an efficiency of 82%. There is no significant head loss. The design conditions have changed, and is now desired to increase the capacity of the pump by increasing the speed. The motor is so designed that its speed maybe increased but its power cannot exceed its design rating. Assuming the pump efficiency to remain constant, how much can the pump capacity be increased without overloading the motor?
Chapter 11 Solutions
Fluid Mechanics
Ch. 11 - Prob. 11.1PCh. 11 - Prob. 11.2PCh. 11 - Prob. 11.3PCh. 11 - Prob. 11.4PCh. 11 - Pl 1.5 What type of pump is shown in Fig. Pl 1.5?...Ch. 11 - Prob. 11.6PCh. 11 - A piston PDP has a 5-in diameter and a 2-in stroke...Ch. 11 - Pl 1.8 A Bell and Gossett pump at best efficiency,...Ch. 11 - Prob. 11.9PCh. 11 - Prob. 11.10P
Ch. 11 - Prob. 11.11PCh. 11 - Prob. 11.12PCh. 11 - Pl 1.13 A 3.5 hp pump delivers 1140 lbf of...Ch. 11 - Prob. 11.14PCh. 11 - Prob. 11.15PCh. 11 - Prob. 11.16PCh. 11 - Prob. 11.17PCh. 11 - Prob. 11.18PCh. 11 - Pl 1.19 A centrifugal pump has r2 = 9 in, b2 = 2...Ch. 11 - Prob. 11.20PCh. 11 - Prob. 11.21PCh. 11 - Prob. 11.22PCh. 11 - P11.23 When pumping water, (a) at what speed...Ch. 11 - Prob. 11.24PCh. 11 - Prob. 11.25PCh. 11 - Prob. 11.26PCh. 11 - Prob. 11.27PCh. 11 - Prob. 11.28PCh. 11 - Tests by the Byron Jackson Co. of a...Ch. 11 - A pump, geometrically similar to the 12.95-in...Ch. 11 - Prob. 11.31PCh. 11 - Prob. 11.32PCh. 11 - Prob. 11.33PCh. 11 - You are asked to consider a pump geometrically...Ch. 11 - Prob. 11.35PCh. 11 - Prob. 11.36PCh. 11 - Prob. 11.37PCh. 11 - Prob. 11.38PCh. 11 - Prob. 11.39PCh. 11 - Prob. 11.40PCh. 11 - Prob. 11.41PCh. 11 - Prob. 11.42PCh. 11 - The 28-in-diameter pump in Fig. 11.7a at 1170...Ch. 11 - Prob. 11.44PCh. 11 - Prob. 11.45PCh. 11 - Prob. 11.46PCh. 11 - PI 1.47 A pump must be designed to deliver 6 m /s...Ch. 11 - Pl 1.48 Using the data for the pump in Prob. Pl...Ch. 11 - Prob. 11.49PCh. 11 - Prob. 11.50PCh. 11 - Prob. 11.51PCh. 11 - Prob. 11.52PCh. 11 - Prob. 11.53PCh. 11 - Prob. 11.54PCh. 11 - Prob. 11.55PCh. 11 - Prob. 11.56PCh. 11 - Prob. 11.57PCh. 11 - Prob. 11.58PCh. 11 - Suppose it is desired to deliver 700 ftVmin of...Ch. 11 - Prob. 11.60PCh. 11 - Prob. 11.61PCh. 11 - Prob. 11.62PCh. 11 - Pl 1.63 A good curve-fit to the head vs. flow for...Ch. 11 - Prob. 11.64PCh. 11 - *P11.65 An 11.5-in-diameter centrifugal pump,...Ch. 11 - Pl 1.66 It is proposed to run the pump of Prob. Pl...Ch. 11 - Prob. 11.67PCh. 11 - Prob. 11.68PCh. 11 - The pump of Prob. P1138, running at 3500 r/min, is...Ch. 11 - Prob. 11.70PCh. 11 - Prob. 11.71PCh. 11 - Prob. 11.72PCh. 11 - Prob. 11.73PCh. 11 - Prob. 11.74PCh. 11 - Prob. 11.75PCh. 11 - Prob. 11.76PCh. 11 - Prob. 11.77PCh. 11 - Prob. 11.78PCh. 11 - Prob. 11.79PCh. 11 - Determine if either (a) the smallest or (b) the...Ch. 11 - Prob. 11.81PCh. 11 - Prob. 11.82PCh. 11 - Prob. 11.83PCh. 11 - Prob. 11.84PCh. 11 - Prob. 11.85PCh. 11 - Prob. 11.86PCh. 11 - Prob. 11.87PCh. 11 - Prob. 11.88PCh. 11 - A Pelton wheel of 12-ft pitch diameter operates...Ch. 11 - Prob. 11.90PCh. 11 - Prob. 11.91PCh. 11 - Prob. 11.92PCh. 11 - Prob. 11.93PCh. 11 - Prob. 11.94PCh. 11 - Prob. 11.95PCh. 11 - Prob. 11.96PCh. 11 - Prob. 11.97PCh. 11 - Prob. 11.98PCh. 11 - Prob. 11.99PCh. 11 - Prob. 11.100PCh. 11 - Prob. 11.101PCh. 11 - Prob. 11.102PCh. 11 - Prob. 11.103PCh. 11 - Prob. 11.104PCh. 11 - Prob. 11.105PCh. 11 - Prob. 11.106PCh. 11 - Prob. 11.107PCh. 11 - Prob. 11.108PCh. 11 - Prob. 11.1WPCh. 11 - Prob. 11.2WPCh. 11 - Prob. 11.3WPCh. 11 - Prob. 11.4WPCh. 11 - Prob. 11.5WPCh. 11 - Consider a dimensionless pump performance chart...Ch. 11 - Prob. 11.7WPCh. 11 - Prob. 11.8WPCh. 11 - Prob. 11.9WPCh. 11 - Prob. 11.10WPCh. 11 - Prob. 11.1CPCh. 11 - Prob. 11.2CPCh. 11 - Prob. 11.3CPCh. 11 - Prob. 11.4CPCh. 11 - Prob. 11.5CPCh. 11 - Prob. 11.6CPCh. 11 - Prob. 11.7CPCh. 11 - Prob. 11.8CPCh. 11 - Prob. 11.1DP
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- For each statement, choose whether the statement is true or false, and discuss your answer briefly: (a) If the rpm of a pump is doubled, all else staying the same, the capacity of the pump goes up by a factor of about 2. (b) If the rpm of a pump is doubled, all else staying the same, the net head of the pump goes up by a factor of about 2. (c) If the rpm of a pump is doubled, all else staying the same, the required shaft power goes up by a factor of about 4. (d) If the rpm of a turbine is doubled, all else staying the same, the output shaft power of the turbine goes up by a factor of about 8.arrow_forwardThe plunger diameter of a single-acting reciprocating pump is 115 mm and the stroke is 230 mm. The suction pipe is 90 mm in diameter and 4.2 m long. If cavitation takes place at the suction head of 4 m, the barometer stands at 10.3 m of water, and the water level in the sump is 3 m below the pump cylinder axis. 3.1 Find the maximum allowable speed to operate the pump 3.2 What power is expected in overcoming friction at this speed, takef = 0.01arrow_forwardA certain centrifugal pump was tested and its performance curves can be approximated as follows: H = 340 - 1.2(Q2), in feet BP = (0.0521Q3) + (1.25Q2) + (11.042Q) + 134.5, in horsepower where Q is in ft3/s. If two of this pump is connected in series to deliver water to a system whose head requirement is 615 ft, what will be the operating discharge rate in ft3/s of either pumps?arrow_forward
- A certain centrifugal pump was tested and its performance curves can be approximated as follows: H = 340 - 1.2(Q2), in feet BP = (0.0521Q3) + (1.25Q2) + (11.042Q) + 134.5, in horsepower where Q is in ft3/s. If two of this pump is connected in series to deliver water to a system whose head requirement is 615 ft, what will be the operating discharge rate in ft3/s of either pumps? Assuming the head is equally divided between the two pumps, what is the efficiency of either pumps (in %)? Take the specific weight of water to be 62.4 lbf/ft3.arrow_forwardQ.2 A centrifugal pump is required to pump water to an open water tank situated 4 km away from the location of the pump through a pipe of diameter 0.2 m having Darcy's fřiction factor of 0.01. The average speed of waterinthe pipe is 2 m/s. If it is to maintain a constant head of 5 m in the tank, neglecting other minor losses, the absolute discharge pressure at the pump exit isarrow_forwardIf a pump requires a minimum of 2.75 m of NPSHA, how high can the centerline of the pump be located above the top of an open tank that supplies 27 C water to the pump? The barometer reads an average of 732 mmHg throughout the year. The tank is 1.82 m high. The pipe friction is 0.7 m and the velocity is 1.22 ?/? .arrow_forward
- A good curve-fit to the head vs. flow for the 32-inch pump in the image shown below is: H(inft)≈500−(2.9E−7)Q2,Qingal/minH(in ft)≈500−(2.9E−7)Q2 , Q in gal/min Assume the same rotation rate, 1170 r/min, and estimate the flow rate this pump will provide to deliver water from a reservoir, through 900 ft of 12-inch pipe, to a point 300 ft above the reservoir surface. Assume a friction factor f = 0.019. Answer in gal/minarrow_forwardAn acceptance test was conducted on a centrifugal pump having a suction pipe 25.4 cm in diameter and a discharge pipe 12.7 cm in diameter. Flow was 186 m³/hr of clear cold water. Pressure at suction was 114.3 mmHg vac and discharge pressure was 107 kPag at a point 91 cm above the point where the suction pressure was measured. Input to the pump was 15 hp. a. Determine the pump efficiency b. If the pump runs at 1750 rpm, what net flow, head, and brake hp would be developed and required if the pump speed were increased to 3500 rpm? Assume constant efficiency.arrow_forward6. A pump is located 4.5 m to one side of, and 3.5 m above a reservoir. The pump is designed for a flow rate of 6 L s'. For satisfactory operation, the static pressure at the pump inlet must not be lower than -6 m of the water gage. Determine the smallest standard commercial steel pipe that will give the required performance. pump 4.5 m. 1.8 19=d 3.5 m 7. water 90° elbowarrow_forward
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