Pipe Flow Rate & Discharge Capacity Calculator

Compute volumetric flow and mass discharge across L/s, m³/h, L/min, US GPM, and UK GPM from known pipe internal bore and flow velocity or pressure gradient.

Design Parameters

Design Flow Rate (Q) *

Simultaneous maximum demand or peak design flow.

Target Velocity (v) Recommended: 1.0 - 1.5 m/s

m/s

Pipe Material & Standard

Roughness: ε = 0.0015 mm (Smooth drawn tube)

Pipe Run Length (L)

Water Operating Temperature

°C

Recommended Commercial Pipe Size

28 mm

BS EN 1057 Table X Half-Hard

Inner Diameter (ID) 26.20 mm

Outer Diameter (OD) 28.00 mm

Wall Thickness 0.90 mm

Minimum Req. ID 23.03 mm

Actual Velocity Optimal

1.39 m/s

Continuity: v = 4Q / (π·D²)

Total Pressure Drop Darcy-Weisbach

21.4 kPa

0.214 bar 3.10 psi

Total Head Loss 85.6 kPa/100m

2.18 m head

7.15 ft of water column

Fluid Mechanics & Friction Verification

Reynolds Number (Re) 36,320 Turbulent Flow

Friction Factor (f) 0.0229 Swamee-Jain

Water Density (ρ) 998.2 kg/m³ @ 20°C

Kinematic Viscosity 1.004 × 10⁻⁶ m²/s

1. Theoretical Internal Diameter via Continuity Equation:

D_req = sqrt(4 * 0.00075 / (π * 1.20)) = 0.02821 m = 28.21 mm

2. Actual Velocity in Selected Commercial Pipe:

v = 4 * 0.00075 / (π * 0.02620²) = 1.39 m/s

3. Reynolds Number Check:

Re = (1.39 * 0.02620) / (1.004e-6) = 36,320 (Turbulent Flow)

4. Darcy Friction Factor (Swamee-Jain):

f = 0.25 / [log10((0.0015/3.7/26.20) + (5.74 / 36320^0.9))]² = 0.0229

5. Darcy-Weisbach Friction Pressure Drop:

ΔP = 0.0229 * (25 / 0.0262) * (0.5 * 998.2 * 1.39²) = 21.4 kPa (0.214 bar)

UK & US Plumbing Standard Tool

Copper Pipe Sizing & Flow Capacity Calculator

Optimized for BS EN 1057 (Table X half-hard tube) and ASTM B88 (Types K, L, M). Enforces strict erosion-corrosion velocity limits per CIBSE Guide G and CIPHE guidelines.

Service Type & Temperature

Required Flow Rate (L/s)

Length of Run (m)

Standard UK Copper Sizes Comparison

Nominal Size	Internal Dia	Flow Velocity	Pressure Loss / 10m	Status

Fluid Flow Capacity Tool

Pipe Flow Rate & Discharge Calculator

Calculate volumetric flow rate Q from known internal diameter and flow velocity, or determine maximum flow capacity from an allowable pressure gradient.

Pipe Internal Diameter (ID)

Fluid Velocity (v)

m/s

Litres per second 0.809 L/s

Cubic Metres / Hour 2.91 m³/h

US Gallons / Min 12.82 GPM

UK Gallons / Min 10.68 GPM

Pipe Flow Rate & Discharge Capacity Calculator

Design Parameters

Fluid Mechanics & Friction Verification

Copper Pipe Sizing & Flow Capacity Calculator

Standard UK Copper Sizes Comparison

Pipe Flow Rate & Discharge Calculator

Pipe Friction & Pressure Loss Calculator

Pipe Velocity & Erosion Limit Checker

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