Question

What is the value of head loss for the fully open gate and butterfly valves?

(a) 0.5 V^2 / 2g

(b) V^2 / 2g

(c) 0.2 V^2 / 2g

(d) 0.04 V^2 / 2g

The question was posed to me during an online interview.

My question is from Dam Outlet topic in section Pressure Conduits, Outlet Works through Dams and Rivers of Irrigation Engineering

Answer 1

Right answer is (c) 0.2 V^2 / 2g

The explanation is: The head loss depends upon the type of gate and valves. For fully open gates and butterfly valves, a loss of about 0.2 V^2 / 2g (where V is the flow velocity through the conduit) may be taken and is taken as nil for ring follower gates.