Question

In a 1920 m long pipeline, the velocity of propagation of pressure wave is 960 m/s. The rapid closure of a downstream valve will entail, when the maximum time for the closure is:
1. 8 s
2. 2 s
3. 6 s 
4. 4 s

Answer 1

Correct Answer - Option 4 : 4 s

Explanation

Given,

L = 1920 m

V = 960 m / s

In the water hammer concept, when the valve is sudden or rapid closure:

\(t ≤ \frac {2 L} V\)

\(t ≤ \frac {2 \times 1920} {960}\)

t ≤ 4 s

So, option 4 is correct

Also, In the water hammer concept, when the valve is gradually closure

if \(t > \frac {2 L}{V}\)