What calculation modes does this liquid pipeline hydraulics calculator offer?

This calculator offers three modes: Pressure Drop (given flow and diameter), Flow Capacity (given pressures and diameter), and Required Diameter (given flow and pressure constraints). It supports both Darcy-Weisbach and Hazen-Williams equations.

When should I use Darcy-Weisbach vs Hazen-Williams for liquid pipeline calculations?

Darcy-Weisbach is viscosity-based and works for all fluids and flow regimes using Colebrook-White friction factor. Hazen-Williams is empirical with a C-factor and is typically used for water systems only. Darcy-Weisbach is preferred for hydrocarbon pipelines.

How does elevation change affect liquid pipeline pressure drop?

Elevation head is calculated as ΔP = SG × 0.433 × Δh, where Δh is the elevation change in feet. Positive elevation change (uphill) increases required pressure, while negative (downhill) decreases it. This is added to friction losses for total pressure drop.

What is the erosional velocity limit for liquid pipelines?

Per API RP 14E, erosional velocity is Ve = C/√ρ where C=100 for continuous service and ρ is fluid density in lb/ft³. Flow velocity should remain below this limit to prevent internal pipe erosion, typically keeping below 80% of erosional velocity.

How do I size a liquid pipeline for a given flow rate?

Use the Required Diameter mode: input your flow rate, available inlet and outlet pressures, pipe length, and fluid properties. The calculator evaluates all standard NPS sizes from 2" to 48" and recommends the smallest pipe that keeps friction losses within the available pressure drop while staying below erosional velocity.

Liquid Pipeline Hydraulics Calculator | Pressure Drop & Sizing

Calculation Mode

Solve For

Pressure Drop Flow Capacity Required Diameter

Friction Equation

Darcy-Weisbach (Colebrook-White) Hazen-Williams

Fluid Properties

Fluid Preset

Liquid Specific Gravity

Viscosity

Pipe Parameters

Flow Rate

Pipe Inside Diameter

10" NPS Sch 40 = 10.020 in

Length

miles

Absolute Roughness

New steel = 0.0018 in; corroded = 0.005–0.01 in

Hazen-Williams C Factor

Elevation & Pressure

Elevation Change

Positive = uphill (outlet higher); Negative = downhill

Inlet Pressure

psig

Outlet Pressure

psig

Learn the Theory

Understand liquid pipeline hydraulics fundamentals, Darcy-Weisbach vs Hazen-Williams, and elevation effects

Read Engineering Guide →

Design Formulas

ΔP = f(L/D)(ρV²/2g_c)/144

ΔP = Pressure drop (psi)

f = Darcy friction factor

L = Pipe length (ft)

D = Inside diameter (ft)

ρ = Fluid density (lb/ft³)

V = Flow velocity (ft/s)

h_f = 10.67·Q^1.852/(C^1.852·d^4.87)

h_f = Head loss per unit length (ft/ft)

Q = Flow rate (GPM)

C = Hazen-Williams coefficient

d = Inside diameter (in)

ΔP_elev = SG × 0.433 × Δh

SG = Specific gravity

Δh = Elevation change (ft)

Limitations & Assumptions

Darcy-Weisbach is valid for all Newtonian fluids and flow regimes; Hazen-Williams is empirical and best suited for water systems
Colebrook-White friction factor solved iteratively (turbulent flow); Hagen-Poiseuille used for laminar flow (Re < 2100)
Assumes steady-state, single-phase, isothermal flow with no surge/water hammer effects
Pipe roughness values are nominal — actual roughness depends on age, service, and condition
Results are for preliminary design — final design requires licensed PE review

Results

Friction Pressure Drop –

Elevation Head –

Total Pressure Drop –

Flow Velocity –

Reynolds Number –

Friction Factor –

Flow Regime –

Erosional Velocity –

Standards & References

Darcy-Weisbach
Fundamental pressure drop equation for pipe flow
Colebrook-White (1939)
Implicit friction factor equation for turbulent flow
Hazen-Williams
Empirical formula for water distribution systems
Crane TP-410
Flow of Fluids Through Valves, Fittings, and Pipe

Liquid Pipeline Hydraulics Calculator

Calculation Mode

Fluid Properties

Pipe Parameters

Elevation & Pressure

Learn the Theory

Design Formulas

Limitations & Assumptions

Results

Standards & References

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