Question 5 [12 Marks] The pump whose performance data is plotted in Figure 4 was operating at a rotational speed of 1950 rpm and had an impeller diameter of 15 m. First, state the affinity law for centrifugal pumps when the impeller varies, then use the equations of the affinity laws to determine the head that would result in a capacity of 4000 L/min. Then, compute the performance of the pump impeller diameter changes to 35 m. Efficiency (%) 30 100 Total Head (m) 200 r 150 Head 100 Efficiency Power 8 500 1000 1500 Pump capacity (gal/min) 0 2000 4000 6000 Pump capacity (L/min) 2000 2500 8000 10000 40 Power (w)

5.19 Consider the piping system shown in the following diagram. The pump operates at 1750 rpm. El 1475' L= 8000'; D = 12";f=0.026 El 1200' Pump 106 Turbomachinery: Concepts, Applications, and Design The pump curve is given by h,=350-24Q² where h, is given in ft. and Q in cfs. What would the head and flow rate delivered be under these conditions? Ans: Q=160 cfs; h,=288 ft 5.20 Solve the previous problem for two identical pumps connected in (a) series and (b) parallel. Ans: a) Q=2.83 cfs, h,=315 ft; b) Q=2.58 cfs; h,=310 ft %D

Example (6-1): At the best efficiency point a centrifugal pump, with impeller diameter D=8 in, produces H= 21.9 ft at Q=300 gpm with N=1170 rpm. Compute the corresponding specific speed using a) U.S. customary units. B) SI units (rad/sec, m/sec, m'/sec").c) European units (rev/sec, m/sec, m/sec?). Develop conversion factors to relate the specific speeds.

Figure below shows the performance curve family of Model 5009 Centrifugal pumps of Taco Pump Inc., running at a fixed speed of N = 1160 rpm. For the pump with the impeller diameter D = 8.625 in., you are asked to determine the best efficiency point (BEP) of the given pump. What is the pump efficiency at BEP? HEAD IN FEET 50 0 0 0 0 40 20 10 O 81% 8.625" 30 (219mm). O 51% O 71% ○ 61% O Taco L/SEC 5 9.25" (235mm) 8.00" (203mm) 7.375" (187mm) 6.75" (171mm) 0 10 15 125 Model 5009 FI & CI Series 20 25 CURVES BASED ON CLEAR WATER WITH SPECIFIC GRAVITY OF 1.0 8 8 52 75% 77% 30 79% 1160 RPM FEBRUARY 19. 2002 35 40 45 REQUIRED NPSH olº 1.5HP (1.1KW) dot 17% Curve no. 2140 Min. Imp. Dia. 6.75" Size 6 x 5 x 9.0 50 55 60 75% 72% 250 375 500 625 FLOW IN GALLONS PER MINUTE 8% 2HP(1.5KW) 750 %09. 55% (2.2KW) 3HP 7.5HP(5.6KW) 2015 do 35% 875 FEET 15 12 -9 6 SHP(3.7KW) 3 0 10 8 NPSH 1000 HEAD IN METERS 5 KPo 45 -36 27 18 9 -0 100 -80 60 -40 2 -20 8 HEAD IN KILOPASCALS