What is the recommended water velocity in pipes?

For water treatment systems, recommended velocities are: suction lines 4-5 ft/s (1.2-1.5 m/s), discharge lines 6-8 ft/s (1.8-2.4 m/s), and RO permeate 3-5 ft/s (0.9-1.5 m/s). Exceeding these velocities causes excessive friction loss, noise, and potential water hammer. Velocities below 2 ft/s may allow sediment settling.

How do you size a pipe for a given flow rate?

Pipe sizing uses the formula: Diameter = sqrt(4 x Flow / (pi x Velocity)). Convert flow to cubic feet per second, choose a target velocity (typically 5-8 ft/s for water), calculate the required internal diameter, then select the next standard pipe size up. Always verify the actual velocity with the selected pipe ID.

What Hazen-Williams C factor should I use?

Common Hazen-Williams C values: PVC/CPVC = 150, new steel = 140, stainless steel = 140, aged carbon steel = 100-120, copper = 140, and concrete = 120-130. Higher C values indicate smoother pipes with less friction. Use lower values for aged or corroded pipe to be conservative.

Water Pipe Sizing & Flow Velocity Calculator

Water Pipe Sizing & Flow Velocity Calculator | ForeverPure

Water Pipe Sizing & Flow Velocity Calculator

Determine optimal pipe diameter, flow velocity, Reynolds number, and friction loss for water treatment piping systems using Hazen-Williams equation.

Application Presets

RO Feed RO Permeate RO Concentrate Boiler Feed Cooling Tower General Service

Input Parameters

Flow Rate

Pipe Material

Maximum Allowable Velocity

ft/s

Suction: 4–5 ft/s | Discharge: 6–8 ft/s | RO permeate: 3–5 ft/s

Pipe Sizing Results

Recommended Pipe Size

Actual Velocity

Reynolds Number

Friction Loss

per 100 ft (Hazen-Williams)

Standard Pipe Sizes (Sch. 40 ID)

Nominal Size	ID (inches)	ID (mm)	Velocity (ft/s)	Friction Loss (ft/100ft)	Status

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