The loss of head due to various pipe fittings such as valves and couplings is expressed as

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JKSSB JE Civil Jal Shakti 6 Dec 2022 Official Paper (Shift 2)

Answer 1

Explanation:

Minor Losses:

These occur due to various fittings, valves, bends, elbows, tees, inlets, exits, contractions, and expansions.

Usually expresses in terms of the loss coefficient KL or resistance coefficient, \({h_L} = {K_L}\frac{{{V^2}}}{{2g}}\)

Reason for loss	Formula
Due to sudden expansion	\({h_L} = \frac{{{{\left( {{V_1} - {V_2}} \right)}^2}}}{{2g}}\)
Due to sudden contraction	\({h_L} = {\left( {\frac{1}{{{C_c}}} - 1} \right)^2}\frac{{V_2^2}}{{2g}}\)
Due to exit from a pipe	\({h_L} = \frac{{{V^2}}}{{2g}}\)
Due to the entrance of the pipe	\({h_L} = 0.5\frac{{{V^2}}}{{2g}}\)
Due to gradual contraction	\({h_L} = {K_L}\frac{{{V_1}^2}}{{2g}}\)
Due to gradual enlargement	~~\({h_L} = {K_L}\frac{{{V_2}^2}}{{2g}}\)~~
Due to bends or pipe fittings	\({h_L} = {K_L}\frac{{{V}^2}}{{2g}}\)
Due to nozzle	\({h_L} = \left( {\frac{1}{{C_v^2}} - 1} \right)\frac{{{V^2}}}{{2g}}\)

Additional Information

Major Losses

Due to friction

When fluid flows from one section to another, there is a reduction in total energy due to friction between the pipe wall and the flowing fluid.
It is given by Darcy Weisbach Equation:

\({h_f} = \frac{{4f'L{V^2}}}{{2gD}} = \frac{{fL{V^2}}}{{2gD}}\)

where, L = length of pipeline, f’ = friction coefficient, D = diameter of pipe, V = average velocity, f = friction factor

f’ is a dimensionless quantity whose value depends upon the roughness coefficient of pipe surface and Reynold's number of the flow.