Post Graduate Department of Irrigation and Hydraulics, Punjab Engineering College, Chandigarh.
The hydraulics of a sprinkler system involves evaluation of pressure variations in the various components in order to achieve an efficient and economical system. The friction loss in the mainline may be computed from the Darcy-Weisbach formula. A corresponding relation has been deduced for pressure loss in a lateral by assuming equal flow in all the sprinklers. The results obtained on this basis are quite high for long lateral lines. A precise solution by step-by-step procedure is quite involved and, therefore, of little practical significance. An improved procedure has been suggested which assumes that the sprinkler discharge varies as square root of the pressure-head. The head-loss is expressed in terms of the average pressure-head at a selected sprinkler located approximately at 1/3 lateral length from the mainline. Though relatively simple, results furnished by this procedure are accurate. The head-loss and pressure recovery in various couplings and pipe fittings have been considered. An algebraic summation of the individual pressure variations provides a conservative estimate of the anticipated head-loss.
Instead of the usual trial and error approach, a direct method of determining the lateral size has been evolved. For determining the pump and motor size the total vertical lift and the overall efficiency of the pumping-unit are taken into consideration.
