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3 Series, paralleland branched pipe

systems

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A. Pipes in Series

Figure 8 Pipes in Series

(32)21

21

QQQ

hhH ff

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ExampleReservoir A delivers to reservoir B through two uniform pipelines AJ:JB

of diameters 300 mm and 200 mm respectively. Just upstream of the

change in section, which is assumed gradual, a controlled discharge of30 l/s is taken off.

Length of AJ = 3000 m; length of JB = 4000 m; effective roughness size

of both pipes = 0.015 mm; gross head = 25.0 m. Determine the

discharge to B, neglecting the loss at J. (Taken = 1.13 x 10-6

m2

/s)

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B. Pipes in Parallel

Figure 9 Pipes in Parallel

(33)

21

21

QQQ

hhHff

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ExampleA 200 mm diameter pipeline, 5000 m long and of effective roughness

0.03 mm delivers water between reservoirs the minimum difference in

water level between which is 40 m.

Taking only friction, entry and velocity head losses into account,

determine the steady discharge between the reservoirs.

If the discharge is to be increased to 50 l/s without increase in gross

head, determine the length of 200 mm diameter pipeline of effective

roughness 0.015 m to be fitted in parallel. Consider only friction losses.

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Branched Pipes

Figure 10 Branched pipes

(34)

213

33

22

1

QQQ

zHh

Hzh

Hzh

jf

jf

jf

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A method of solution is as follows:

1. Guess Hj

2. Calculate Q1, Q2, and Q33. If Q1 + Q2 = Q3, then the solution is correct

4. If Q1 + Q2 Q3, then return to (1)

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Example

Determine the discharges in the pipes of the network shown belowneglecting minor losses.

Pipe Length (m) Diameter (mm)

AJ 10000 450

BJ2000 350

CJ 3000 300

DJ 3000 250