Question

Minor losses in a piping system are
1. Less than the friction losses \(f~\frac{l}{d^2}\frac{v^2}{g}\)
2. Due to the viscous stresses 
3. Assumed to vary linearly with the velocity
4. Found by using loss coefficients

Answer 1

Correct Answer - Option 4 : Found by using loss coefficients

Explanation:

Minor loses caused by the disruption of the flow due to the installation of appurtenances, such as valves, bends, and other fittings.

• Minor losses are usually expressed in terms of the loss coefficient K_L also called the resistant coefficient and it is defined as,

\(K_L~=~\frac{h_L}{\frac{V^2}{2g}}\)

where K_L = loss coefficient, H_L = loss of head, V = velocity of fluid

• In some cases, the minor losses may be greater than the major losses, for example, in a system where several turns and valves in a short distance.
• Following are some minor losses which occur in pipe flow:
  • Loss of energy due to sudden enlargement
  • Loss of energy due to sudden contraction
  • Loss of energy at the entrance of the pipe
  • Loss of energy at the exit from pipe
  • Loss of energy in Bends and Pipe Fittings

Major losses: Whenever the losses in the pipes are because of friction they are considered as major losses because there is a significant loss of energy because of friction.

According to Darcy’s Weisbach equation:

Major loss (hL): this is the head loss due to friction.

\({h_L} = \frac{{fL{V^2}}}{{2gD}}\)

where f = friction factor, L = length of pipe, V = velocity of flow, D = diameter of the pipe