Current capacity flow is design maximum 191 million gallons

Current capacity flow is design maximum 19.1 million gallons and peak pressure 45 million gallons. I This is for 11 inch diameter lines. If you were to expand lines to 15 inches how would that change flow? What about to 20 inches?

Solution

The question is not clear about the design maximum flow conditions.

However, assuming that the max pressure flow occurs when the maximum pumping head is applied on the system.

We will solve the question using Hazen-Williams equation.

The Hazen-Williams equation for calculating head loss in pipes and tubes due to friction can be expressed as:

P_d = 4.52 q^1.85 / (c^1.85 d_h^4.8655)    

where

P_d = pressure drop (psi/ft pipe)

c = design coefficient determined for the type of pipe or tube - the higher the factor, the smoother the pipe or tube

q = flow rate (gpm)

d_h = inside hydraulic diameter (inches)

In this case, Pd and C are constant for all the cases since flow will be calculated based on the maximum pressure head and C will remain same until MOC of the pipes are changed

Therefore for all the case,

q^1.85 / d_h^4.8655 = Constant

(45^1.85 / 8^4.8655) = (Q15^1.85 / 15^4.8655)

Or, Q15 = 235

Flow in 15” pipe = 235 million gallon

Similarly flow in 20” pipe =Q20 = 500.85 Million Gallon