pipework system

Water is transported from a reservoir to a storage tank via the pipework system shown below. The pump station is to incorporate three TKL 200200500HT pumps, arranged in parallel as shown below. The pumps operate in a duty-standby arrangement, such that only two pumps operate at a time (while the other pump sits idle). The design duty flow rate for the system is 260l/s. All pipes are cement mortar lined steel. The main pipe diameter is 400mm, and the pipework in the parallel section is 250mm in diameter - you may neglect the straight pipe losses in the parallel section, but not the fitting losses. (a) Calculate Hp for 3 points (flow rates) on the system curve; - No flow - Half the duty flow - The duty flow From the results, determine the impeller diameter required to achieve the duty point. You do not need to plot the points on a chart - following the usual calculation routine and providing a final table showing the system curve calculations will be sufficient. All usual working must be shown for full credit. (b) Rather than trimming the impeller to the diameter determined in part (a), one of your team suggests leaving the impeller diameter at the maximum possible diameter of 512mm, so that the pump will run for less time over the course of the year to deliver the required total volume of water. Which option (trimming or not trimming) would you recommend, and why? Storagetank 22 metres Elevation change Parallel Section Length 15m (each pump) Diameter 250mm Cement Mortar Lined Steel Reservoir Bellmouth Inlet Main Pipework Length 5.87km Diameter 400mm Cement Mortar Lined Steel P P P All Bends 90 degree Medium radius elbows All Valves (except check valves) Fully Open Gate Valves