# For a saddle siphon, the maximum operative head is 4.53 m. The width and height of the throat of the siphon are 5 m and 2.25 m respectively. The coefficient of discharge is 0.90. How many units are required to pass a flood of 350 cumecs? (Assume g = 10 m/s^2)

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For a saddle siphon, the maximum operative head is 4.53 m. The width and height of the throat of the siphon are 5 m and 2.25 m respectively. The coefficient of discharge is 0.90. How many units are required to pass a flood of 350 cumecs? (Assume g = 10 m/s^2)

(a) One

(b) Two

(c) Three

(d) Four

I have been asked this question at a job interview.

My question comes from Shaft Spillway topic in chapter Spillways, Energy Dissipators and Spillway Gates of Irrigation Engineering

by (106k points)
The correct option is (d) Four

To explain I would say: The discharge through the siphon is given by the equation:

Q = Cd. A. (2gH)^1/2 Where Cd = 0.9, H = 4.53 m and A = 5 x 2.25 = 11.25 m^2

Q = 0.9 x 11.25 x (2 x 9.81 x 4.53)^1/2 = 95.45 m^3/sec

No. of units of saddle siphon = 350 / 95.45 = 3.66 units. = 4 units.

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