3. Gasoline Pipeline (with pump) (35%): We wish to pump gasoline from tank B o t

Question

3. Gasoline Pipeline (with pump) (35%): We wish to pump gasoline from tank B o tank A as shown in the figure. We will use the 6 in diameter pipe and All pipe: install a centrifugal pump (pump chart given D 6 in PA 10 psig. below). 0.005 ft (a) Using this pump, what would be the gasoline A 40 ft u 900 ft Tank flow rate, operating head, efficiency, and brake P 40 psig horsepower? Assume highly turbulent flow. (15 Tank B points) 10 ft- (b) Gasoline has a vapor pressure of vapor pressure Gasoline of 4.0 psia. For the conditions in part (a), will the 0 ft. pump cavitate? (0 points) La100 ft

Explanation / Answer

solution:

1)here manometric head of pump is given by

Hm=(Pb/density+Zb-Pa/density-Za-(flv^2/2gd))

l=900*2+100=1900 ft

d=6'' or .5 ft

so we get where V=4Q/pi*d^2=5.092Q

Hfs=flv^2/2gd=7.653Q^2

so we get Hm as

Hm=1918.073+(40-10)-7.653Q^2

where pump curve is

Hp=200-3*10^-5Q^2

on equating Hm and Hp we get that

Q=15.1133 gpm or .0336 ft3/s

by Hp=200-3*10^-5*Q^2=199.9931 ft

hence pump power is

P=density*g*Q*Hp=570.07 watt

4)where pump to lift water for Q=1500 gpm

Hp=200-3*10^-5Q^2=132.5 ft

Q=3.342 ft3/s

here from graph

NPSH=9.5 ft

where specific spped of pump is Ns=N(Q)^.5/Hp^.75

N=2300

Ns=107.66 rpm

where by cavitation suction specific speed is

Ns/Nss=(NPSH/Hp)^.75

Nss=777.035 rpm

to avoid cavitation

Ns>Nss

means at this flow rate pump will cavitate

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