The introduction notes say that flex hose losses can vary greatly. What does that mean in terms of the margin of error in the spreadsheet?
There are many ways to manufacture flex hose. If the hose is made with a smooth interior it will have significantly less resistance than a pipe made with an interior covered in ridges and valleys. Also, if the hose allows tight bends it will have far more resistance than a flex hose that severely limits bending. Understandably, flex hose makers are reluctant to share static pressure losses and generally only share loss factors as roughly three times the losses for straight pipe. The only published losses I could find are based on a hose reel manufacturer. They worked out to 2.25x the pipe loss in 4″, 3.2x the pipe loss in 5″, and 3.45x the pipe loss in 6″. Those are the factors used in the spreadsheet. Without knowing precisely what kind of flex those are based on, I can only assume it is the smoothest inside wall available. Generally you want to use as little flex pipe as possible, and then use only the smoothest inner wall flex pipe you can find. Also, try to install the flex pipe as
