Correct Answer - Option 3 : the algebraic sum of the piezometric head drops around each elementary circuit is zero
Concept:
In any pipe network following two rules must be satisfied:
1. The algebraic sum of the piezometric head (pressure head + datum head) drops around each elementary circuit (or each closed loop) must be zero, i.e. there cannot be any discontinuity in piezometric heads.
2. The flow entering a junction (or node) must be equal to the flow leaving the same junction, i.e. the law of continuity must be satisfied.
Note:
- The algebraic sum of discharges around each elementary circuit cannot be zero because if it would be zero then no net discharge would be available to pass into next elementary circuit i.e. flow in the network would not be possible.
- The head at each node cannot be same because if there is no head difference, the flow would not occur in the pipe network.
- The piezometric head loss in each line of the circuit cannot be the same as it depends upon the datum height, length and diameter of the line.
∴ In a pipe network the algebraic sum of the piezometric head drops around each elementary circuit must be zero.
