Question

A centrifugal pump takes brine from the bottom of a supply tank and delivers it into the bottom of another tank. The brine level in the supply tank is 150 ft below that of the other tank. The line between the tanks is 600 ft of 4" Sch. 40 pipe. The friction factor for a flow of 400 gpm is 0.0045. In the line are 2 gate valves, 4 branch run tees, and 4 (90) deg elbows. What is the equivalent length (feet) of the piping system?

Answer 1

Here the we will have to convert the bends into equivalent lengths in order to obtain the total equivalent length

Now here

L = 600 ft

The dimensions of pipe are 4'' schedule 40

which is 4.5 inch OD = 0.375 fT

D = 0.375 ft

Now we have 2 gate valves

For gate valves

(L/D) = 8

L = 8 *D = 8*0.375 =3 ft

we have 2 Globe vavles

Lglobe = 2*3 = 6 ft

Now we have 4 branch run tees

(L/D) = 20

L = 20*0.375 =7.5ft

we have total of 4 branch through Tess

Ltees = 4*7.5 = 30 ft

Also there are 4 90 degree elbow

(L/D) =30

L = 30*0.375 =11.25 ft

there are 4 90 degree elbow

Lelbow = 4*11.25 =45 ft

Lequivalent = L +Lgate + Ltees +Lelbow = 600 +6+30+45 =681 ft

Hence the equivalent length for the above system is 681 ft