Calculate pressure drop in steam distribution pipe lines

[Esam]

The pressure drop in saturated steam distribution pipes can be calculated in metric units as

dp = 0.6753 10⁶ q² l (1 + 91.4/d) / ρ d⁵ (1)
where
dp = pressure drop (Pa)
q = steam flow rate (kg/h)
l = length of pipe (m)
d = pipe inside diameter (mm)

ρ = steam density (kg/m³)

Note that the pressure drop calculated might be higher than the actual values at higher velocities.
The Unwin formula can also be expressed in imperial units as

dp = 0.0001306 q² l (1 + 3.6/d) / (3600 ρ d⁵)(2)
where
dp = pressure drop (psi)
q = steam flow rate (lb/hr)
l = length of pipe (ft)
d = pipe inside diameter (inches)

ρ = steam density (lb/ft³)

[h=Example - Pressure Drop in Steam Pipe]3[/h] Steam, 4000 kg/h at 10 bar (1000 kPa) pressure with density 5.15 kg/m³ flows through a schedule 40, ND 100 steel pipe, inside diameter 102 mm and length 100 m. The pressure drop can be calculated as

dp = 0.6753 10⁶ (4000 kg/h)² (100 m) (1 + 91.4/(102 mm)) / ((5.15 kg/m³) (102 mm)⁵ )
= 36030 Pa
= 36 kPa