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Irrigation Pump & Pipe Sizing Calculator

Hazen-Williams friction loss, total dynamic head, pump HP, and energy cost per acre-inch

Size irrigation mainlines and pump systems using Hazen-Williams friction loss calculations. Enter your flow rate, pipe material, diameter, length, fittings, and elevation to get total dynamic head, required pump HP, flow velocity checks, and energy cost estimates per hour and per acre-inch.

Pro Tip: Keep pipe velocity under 5 ft/s for PVC and 7 ft/s for steel. Higher velocity doesn't just waste energy — it causes water hammer that can crack fittings and burst pipes.

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Irrigation Pump & Pipe Sizing Calculator
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How It Works

  1. Enter Flow Requirements

    Input target flow rate (GPM) and select pipe material (PVC, aluminum, HDPE, steel new, steel aged) and pipe size.

  2. Enter System Details

    Input total pipe length, elevation change, delivery pressure, suction head, and add any fittings (elbows, tees, valves) for equivalent length calculation.

  3. Review Pump Sizing

    See total dynamic head (TDH), required pump HP, velocity check, and energy cost estimates. Use the pipe comparison table to evaluate alternative sizes.

Built For

  • Farmers sizing new irrigation systems
  • Irrigation dealers designing systems for customers
  • Well drillers recommending pump sizes
  • Farm managers evaluating irrigation energy costs

Frequently Asked Questions

PVC (C=150) is the most common for buried mainlines — smooth bore, corrosion-resistant, and affordable. Aluminum (C=130) is standard for portable surface pipe. HDPE (C=150) is increasingly used for flexibility and durability. Steel is used for high-pressure applications but rusts over time (C drops from 140 new to 100 aged).
The Hazen-Williams formula is: friction loss (psi/100ft) = 0.2083 × (100/C)^1.852 × GPM^1.852 / ID^4.8655. C is the pipe roughness coefficient (higher = smoother), GPM is flow rate, and ID is inside diameter in inches.
A typical quarter-mile center pivot needs 600-900 GPM at 40-60 PSI, depending on nozzle package and system pressure. Total dynamic head typically runs 120-200 feet when you add friction loss, elevation, and pressure. That translates to 40-75 HP depending on efficiency. Enter your specific numbers in this calculator for an exact answer.
Disclaimer: Pump and pipe sizing calculations are estimates based on Hazen-Williams formulas. Actual performance depends on pipe condition, water quality, and pump characteristics. Consult a pump dealer or irrigation engineer for system design.

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