Hazen-Williams Calculator: Pipe Friction Loss in Seconds (Formula + Table)
Calculate pipe friction loss using Hazen-Williams instantly. Complete C values table, formula explanation, and step-by-step example. Free guide.
Hazen-Williams Friction Loss Calculator
The Hazen-Williams equation is the quickest way to calculate friction head loss for water flowing in pipes. Here's how to use it and what tool automates it.
The Formula
hf = 10.67 × L × Q^1.852 / (C^1.852 × D^4.87)| Variable | Description | Unit |
|---|---|---|
| hf | Head loss | m |
| L | Pipe length | m |
| Q | Flow rate | m³/s |
| C | Roughness coefficient | dimensionless |
| D | Internal diameter | m |
Quick Reference: C Values
| Material | C (new) | C (aged) |
|---|---|---|
| PVC / CPVC / HDPE | 150 | 140 |
| Copper | 150 | 130 |
| Stainless steel | 140 | 130 |
| Galvanized steel | 120 | 90 |
| Cast iron | 130 | 90 |
| Ductile iron | 140 | 120 |
| Concrete (smooth) | 130 | 110 |
Full table with 20+ materials: Hazen-Williams C values table
Step-by-Step Calculation
Problem: 100 m of 4" PVC pipe (D = 101.6 mm), flow rate 15 L/s.
Step 1: Convert units
D = 0.1016 m
Q = 0.015 m³/s
C = 150 (PVC new)
L = 100 mStep 2: Calculate
hf = 10.67 × 100 × 0.015^1.852 / (150^1.852 × 0.1016^4.87)Breaking it down:
Q^1.852 = 0.015^1.852 = 3.97 × 10⁻⁴
C^1.852 = 150^1.852 = 10,545
D^4.87 = 0.1016^4.87 = 1.14 × 10⁻⁵
hf = 10.67 × 100 × 3.97×10⁻⁴ / (10,545 × 1.14×10⁻⁵)
hf = 0.4236 / 0.1202
hf = 3.52 mResult: 3.52 m of friction loss over 100 m of 4" PVC pipe at 15 L/s.
Common Mistakes
- Using nominal diameter instead of internal diameter. A "4-inch" pipe has an ID of about 101.6 mm, not 100 mm. This matters because D is raised to the 4.87 power.
- Using C for new pipe on old systems. A 20-year-old steel pipe has C ≈ 100, not 120.
- Applying H-W to non-water fluids. The equation is empirical and calibrated for water only.
- Exceeding velocity limits. H-W is valid for 0.6-3.0 m/s. Check velocity: V = Q/A.
When NOT to Use Hazen-Williams
- Fluid is not water (use Darcy-Weisbach)
- Temperature outside 5-25°C (use Darcy-Weisbach)
- Velocity outside 0.6-3.0 m/s (use Darcy-Weisbach)
- You need high precision (use Darcy-Weisbach)
Automate It with HydroApp Pro
HydroApp Pro calculates Hazen-Williams friction loss automatically for every pipe segment. Select the material, and the C value is applied from the built-in table. Supports aged pipe values and mixed materials in the same network.
Also calculates Darcy-Weisbach in parallel, so you can compare both methods instantly.
Try HydroApp Pro — Hazen-Williams + Darcy-Weisbach calculator. $99 one-time.
Related
¿Cansado de calcular esto a mano?
HydroApp Pro automatiza todo el calculo hidraulico. TDH, perdidas por friccion, NPSH, punto de operacion y reportes PDF. En 2 minutos.
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