I am designing a water transmission main from a source to a community. The community contain different Blocks, each one has underground storage tank. The idea is to install the pump the source and fill each tank one by one using the same set of pumps. As the blocks have different length from the source and different elevation difference as compare to each other and source, therefore I calculated the pump head considering the worst head loss required from source to a blocks.
Now using that pump head, I am getting very high terminal head/residual pressure for the remaining blocks. To utilize the available head I reduce the diameters of pipes and limit the velocity in pipe to 3.4m/sec. (we are using HDPE pipe)
Now I have the following questions
1- Is it possible to use centrifugal pump with vfd so that it can supply constant flow rate but vary pump head as per requirement?
2- Is it better to loss the head using valves?
3- Is it safe to take velocity up to 3.4m/sec . May result in water hammer?