Pipe friction can have a significant impact to a pump’s performance – long discharge pump runs (even if they are flat and not a part of the head calculation) should always be calculated when determining the right equipment for the job. If you are asking for our guidance on pump selection, long discharge runs should always be mentioned in that initial call to Hydra-Tech Pumps. Pipe friction reduces flow - here’s an example to walk you through the calculation.
Say you are planning on using an S4THL and an HT35DYS to move some water. The job calls for pumping 500 gallons per minute at a head of 50’. The S4THL’s A curve (based on the hydraulic output available from the HT35DYS) tells you that at 50’ you are right at the 500 gallons per minute mark. However, in addition to the vertical head requirement, you will also be pumping through 400’ of smooth bore 4” ID plastic discharge pipe. We have a tool on our computers that allows us to enter the data necessary to determine what the pipe friction loss will add to the original head number. Below is the calculation where we entered the discharge pipe ID (4”), the length of the discharge hose (400’) the expected flow of the pump based on the 50’ of head already calculated (500 GPM), and the Hazen-Williams Coefficient. The result of the pipe friction loss is 52.39 feet of head, so I add that to my original head of 50 feet for a total of 102.39 feet of head.