Pipe Friction Pressure Drop

Velocity, Reynolds number, Haaland friction factor, and Darcy–Weisbach loss from pipe and fluid properties.

Fluid & Pressure

Velocity, Reynolds number, Haaland friction factor, and Darcy–Weisbach loss from pipe and fluid properties.

App id: FLUID-07. Reference version 1.0.

How to fill it

Fill the inputs. The tool shows the outputs.

On the tool screen, Calc is the working sheet. Presets stores values you reuse. Reference is the formula, assumptions, and provenance below.

Formula

v = 4Q/(πD²); Re = ρvD/μ; ΔP = f (L/D) (ρv²/2)

Inputs

Name	Unit
Volumetric flow (camera)	`m3/s`
Inside diameter	`mm`
Pipe length	`m`
Density	`kg/m3`
Dynamic viscosity	`Pa-s`
Absolute roughness (optional)	`mm`
Gravity (optional)	`m/s2`

Outputs

Name	Unit
Pressure drop (hero result)	`kPa`
Head loss	`m`
Mean velocity	`m/s`
Reynolds number	`1`
Darcy friction factor	`1`

Diagnose

Observations are context. They do not pass or fail a structure. See Diagnose.

Screening bands in the app: Laminar · Transitional · Turbulent.

When	Observation	Severity
`Mean velocity < 0.3`	Low velocity	info
`Mean velocity > 5`	High velocity	caution
`Mean velocity > 3`	Elevated velocity	info
`Reynolds number < 2300`	Laminar	info
`Reynolds number ≤ 4000`	Transitional	caution
`Reynolds number > 4000`	Turbulent	info
`relative > 0.05`	Very high relative roughness	caution

Assumptions

Full circular pipe, constant diameter.
Leave roughness blank for a smooth pipe.
Pressure drop alone does not mean the pipe is undersized.

Provenance

Darcy–Weisbach with Haaland f. Straight pipe only — fittings are not included.