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Engineering Toolbox/Pipe Flow / Velocity

Pressure, Level & Process

Pipe Flow / Velocity

Convert actual volumetric flow and average velocity for a circular pipe using its internal diameter. The tool is intended for field screening and instrument/process checks, not final hydraulic design.

Flow / velocity calculator

Uses the unobstructed internal pipe area.

The selected flow unit above is used for the primary reverse-conversion result.

For gas or steam, enter actual volumetric flow at flowing line conditions. Do not enter SCFD, MSCFD, MMSCFD or another standard/base-condition volume directly.

Field use

A quick process and instrumentation screening calculation.

Useful when checking a flowmeter reading against expected line velocity, converting an actual flow to pipe velocity, or estimating actual flow from a known average velocity and internal diameter.

Calculation basis

A = πD² / 4
Q = vA   →   v = Q / A

D is the actual pipe internal diameter, A is unobstructed cross-sectional area, Q is actual volumetric flow, and v is average fluid velocity.

This tool does not determine acceptable design velocity, erosional velocity, Reynolds number, friction loss, compressibility correction, two-phase slip, flow profile, meter straight-run requirements, or line sizing. Schedule/NPS alone is not accepted because velocity depends on actual internal diameter.

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