4" Fire Hose Friction Loss Calculator
This friction loss calculator is used to determine the friction loss on one (or more) 100 foot section of 4 inch fire hose.
How to use: The left column lists the gallons per minute (GPM). The right column is the friction loss (FL), measured in PSI (for each 100' section fire hose). Start by determining the GPM & PSI being pumped (ex: 500 GPM & 150 PSI), then scroll through the left hand column (GPM) for the GPM being pumped and look for the corresponding PSI drop (FL) (ex: 500 GPM = 5 PSI drop). Then subtract the PSI drop from the PSI at the pump (ex: 150 PSI - 5 PSI = 145 PSI). This shows you that the pressure at other end of a 100' section of 4" fire hose pumping 500 GPM at 150 PSI will be ~145 PSI. More advanced instructions can be found at Fire Engine Academy "Setting Pump Pressure"If you have more than one 100' section of 4" fire hoses (in series), multiply the number of 100' sections, by the friction loss value in the right column (example: (150 - (2*5)= 140 PSI).
* Each brand/style of 4" fire hose has a slightly different diameters and friction loss. And, adding hardware (inline T's, Gated Y's, etc) adds friction.
If you find this friction loss calculator useful, please share it with other firefighters!