Graph Software for Scientists and Engineers

N1.85 Hydraulic Scale

This graph type is typically used in hydraulic studies, particularly for fire suppression systems. The horizontal coordinates of the graph are scaled to the 1.85 power because, in the Hazen-Williams formula, pressure is proportional to the flow to the 1.85 power. The Hazen-Williams formula will therefore plot as a straight line using this scale type.

From Wikipedia:

The Hazen-Williams formula can be used to calculate the pressure loss in a length of pipe due to friction dependent on the flow. This equation is commonly used for pressure drop calculations in American fire sprinkler systems, water distribution systems, and irrigation systems.

N1.85 Scaling


Pd=pressure drop in pounds per square inch / foot

Q = flow, gallons per minute

C = factor (friction loss coefficient) - the higher the C factor, the smoother the pipe. Typical C factors used in design, which take into account some increase in roughness as pipe ages are as follows:

Asbestos-cement - 140
Cast iron - 100
Concrete - 100
Copper - 130
Galvanized steel - 100
Polyethylene - 140
PVC - 150

d = inside diameter in inches

N1.85 Hydraulic Scale
Windows 10,
Windows 8,
Windows 7, 2008,
Vista, XP, NT,
ME, 2003, 2000,
Windows 98, 95
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