A Simplified and Accurate Method of Computing Inlet Head of Multi-Outlet Pipelines

The multi-outlet pipelines normally called as lateral lines are the major important components of the
micro irrigation and sprinkler irrigation systems. To maintain the allowable discharge variation of the
outlets, the variation in pressure along the length of the pipelines due to frictional head loss and
elevation is restricted within a specified limit. In this process, the accurate computation of the inlet
head of the lateral lines becomes necessary for proper design of the system. The generally used
formulae of computing the inlet heads involve different values of coefficients quoted in literature
without proper justification. This leads to over or under computed values of the inlet head. In this
paper, equations are developed to accurately compute the value of the inlet head of lateral lines. The
equations are based on the mathematical series of varying discharge from one outlet to other. The
equations are simplified using mathematical logics and finally obtained in the compact forms to be
used with the exponents of flow and diameter of different frictional head loss formulae. The verification
and application of the formulae are illustrated with the standard example problems. The developed
formulae can be easily and accurately used for computing the inlet head of lateral lines of micro
irrigation and sprinkler irrigation systems.