What is the discharge of an 8 inches pipe 130 meters above sea level to a tank 30 meters above sea level.?

Question

What is the discharge of an 8 inches pipe 130 meters above sea level to a tank 30 meters above sea level.?

Answer 1

Q = cAV

Where:

Q = rate of discharge

c = Coefficient of discharge

A = are of the pipe

V =velocity of discharge

Assuming that he coefficient of discharge for a circular pipe is c =0.8;

V = sqrt (2gh)

h = (130 -30) 3.28 = 328 ft.

= 32ft/s^2

V = 102.45 ft/sec

A = (pi(8^2)/4)/144 = 0.3491 sq.ft

Q = 0.8 x 102.45 x 0.3491 = 28.609 cu ft/sec

Answer 2

Draco 4843 is correct if you ignore the friction in the pipe, but at 102ft/sec this will be considerable.

I think that the formula to use is

H = 16 x friction coeff x L Q^2 / (2gPI^2D^5)

H = 100m

Friction coeff (lambda) = 0.2

L = say 200m

D = 0.2m

so Q = (H x 2 xg x PI^2 x D^5/(16 x 0.02 x 200))^0.5

Q = 0.44m3/sec

V = 14m/sec