This chart may be used to compute friction losses in a piping system. For example, determine the friction loss incurred when 70 CFM flows through a 2" pipe, 50' long.

Step 1: Intersect 70 CFM and the sloping line for 2" pipe as shown.
Step 2: Drop a vertical from this point of inter section and read the loss/100' of line, in this case, .60 Hg/100'.
Step 3: Multiply the loss/100' of line by the length of run/100'.

The loss for 50', then, is: