The calculator to calculate the pressure loss in a pipe, duct or tube. The conditon is 20oC, 1.2 kg/m3 and 6 m/s.
Δp = λ (l / dh) (ρ v2 / 2)
where
λ = Darcy-Weisbach friction coefficient
dh = hydraulic diameter(m)
ρ = density (kg/m3)
l = length of duct or pipe (m)
Δp = pressure loss (Pa, N/m2)