Darcy-Weisbach · Swamee-Jain · Pressure Drop · Velocity Analysis
Professional Liquid Line Sizing
Calculate optimal pipe size for liquid service using Darcy-Weisbach equation with corrected Swamee-Jain friction factor. Analyzes pressure drop, velocity, Reynolds number, and flow regime for all standard pipe sizes.
Flow Conditions
-
Water = 1.0, typical range: 0.7-1.6
cP
Water @ 60°F ≈ 1.0 cP
Pipe Properties
ft
Commercial steel: 0.0018 ft
Design Criteria
ft/s
Typical: 5-15 ft/s
psi/100ft
Economic optimum: 1-2 psi/100ft
📚 Learn the Theory
Understand liquid line sizing principles, calculations, and industry applications
• Pump suction: 1-5 ft/s
• Water discharge: 5-15 ft/s
• Oil pipelines: 3-8 ft/s
• Heavy oils: 2-5 ft/s
⚡ Key Tips:
• Use viscosity at actual operating temperature
• Target Re > 4000 for turbulent flow (more efficient)
• Cold oil = higher viscosity = higher ΔP
• Heating heavy oils reduces pumping costs
• Aged pipe: increase roughness to 0.003-0.005 ft
Analysis Summary
💧 Common Fluids @ 60°F
Fluid
SG
μ (cP)
Water
1.00
1.1
Gasoline
0.72
0.6
Diesel
0.85
4.0
Kerosene
0.81
2.2
Light Crude
0.86
10-20
Med Crude
0.92
50-100
Heavy Crude
0.95
200-1000
Fuel Oil #2
0.87
5
Fuel Oil #6
0.98
900*
Ethanol
0.79
1.2
Glycol (50%)
1.07
5.5
*Requires heating. μ varies greatly with temp.
Pipe Roughness Values
Material
ε (ft)
Commercial Steel
0.00015
Carbon Steel (new)
0.0018
Stainless Steel
0.00015
PVC
0.000005
Copper
0.000005
⚠️ Limitations
Newtonian liquids only
Single-phase flow
No gas-liquid mixtures
No slurries/polymers
Viscosity < 10,000 cP
🎯 Velocity Guide
Pump Suction
1-5 ft/s
Water Discharge
5-15 ft/s
Oil Pipelines
3-8 ft/s
Heavy Oils
2-5 ft/s
Target Re > 4000 for turbulent flow (more efficient)